This is just one of some 80 files about machining and metalworking and useful workshop subjects that can be read at: http://www.janellestudio.com/metal/index.html ------------------------------------------------------------------ This file contains a good bit of information about gear use, gear repair, and making gears. For those with a metal shaper, there is additional gear making information in the text file "Metal Shaper Operating Tips". And for those without a shaper, you just might want to skim through the shaper files to see what that device's attraction for machinists is about. Besides the allure of owning hulking lumps of historic iron, enthusiasts soon appreciate the number of operations that would today be done on a milling machine. Consider that shapers are cheap, simple, and use inexpensive lathe-type single point cutters that the home user can form and resharpen easily with a simple grinder. Aha, the light turns on. If you got to this file directly from my HOME PAGE, return there by using your browser's back button. BUT if you came to this file as the result of a web search engine, see many additional files on my home page Machining and Metalworking at Home http://www.janellestudio.com/metal/index.html SAFETY WARNING BEWARE: DO NOT ASSUME that any subject matter or procedure or process is safe or correct or appropriate just because it was mentioned in a news/user group or was included in these files or on this site or on any other web site or was published in a magazine or book or video. Working with metals and machinery and chemicals and electrical equipment is inherently dangerous. Wear safety devices and clothing as appropriate. Remove watches, rings, and jewellery -- and secure or remove loose clothing -- before operating any machine. Read, understand and follow the latest operating procedures and safety instructions provided by the manufacturer of your machine or tool or product. If you do not have those most recent official instructions, acquire a copy through the manufacturer before operating or using their product. Where the company no longer exists, use the appropriate news or user group to locate an official copy. Be careful -- original instructions may not meet current safety standards. Updated safety information and operating instructions may also be available through a local club, a local professional in the trade, a local business, or an appropriate government agency. In every case, use your common sense before beginning or taking the next step; and do not proceed if you have any questions or doubts about any procedure, or the safety of any procedure. Follow all laws and codes, and employ certified or licenced professionals as required by those laws or codes. Hazardous tasks beyond your competence or expertise should also be contracted to professionals. Let's be really careful out there. (c) Copyright 2003 - 2016 Machining and Metalworking at Home The form of the collected work in this text file (including editing, additions, and notes) is copyrighted and this file is not to be reproduced by any means, including electronic, without written permission except for strictly personal use. ======================================================================== NOTE TO FILE: This next thread was put at the start of this file (and out of normal date order) as it gives a good introduction to the subject of cutting gears -- along with some reference reading. Tom, thank you. ------- Date: Tue, 12 Apr 2005 23:50:47 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Re: Gear Cutting On Wed, 13 Apr 2005, schan117taig wrote: >Hi guys: Anyone around know how simple but large industrial gears are cut? >I recently read some literature saying that the gear blank is being held >on an indexable chuck with the cutting wheel spinning at 90 degrees wrt >the blank. Then the teeth are being cut as the wheel approaches the blank. >Anyone know how the gear blanks are being held on those gear >cutting machine? what about the tool? I have found out that Gleason >seems to be the leader in the gear cutting industry. Any other sources >for literature and equipment for gear cutting? Ooooh boy. You don't ask easy ones, do you? There's a lot out there on gear cutting, but finding the information can be like pulling teeth. A couple of years ago I went on a literature exodus on the subject. Here's some of what I've found: A lot of gears are cast and finished. Nylon and Delrin gears tend to be injection molded. Thin metal gears can also be cut using a stamping press. It all depends on what you're after. Ignoring the other processes, I'll get back to your question on actual gear cutting. There are a number of ways to cut a gear. One is the process you mentioned, using a form cutter that dictates the tooth form. Another is hobbing, where the tooth form is generated during the cutting process (the cross-section of a hob doesn't necessarily look like the cross-section of the tooth it generates.) Another is shaping, which is also a generating process like the hobbing process. One reason I mention this last one is that Gleason makes gear shaping machines, so you may run across it if you're searching through their literature. (If you've got a shaper in your shop or happen to have a Gleason gear shaper handy, I'd urge you to read up on it. It's pretty darned neat.) Before I get back to the form cutters, I'll touch on hobbing just briefly: On the whole gear hobbing isn't considered something that's done in the home shop. But people on this list have used the hobbing process to make gears, some with really good results. In case you run across the term while you're looking into gear cutting, this would be a good place to ask more questions about it. There are more knowledgeable heads than mine here who'd be able to fill you in on all the nitty-gritty details. Back to cutting! You can get form cutters commercially. Check in Enco and MSC. They sometimes show up. If not, Grainger typically carries them. Specialty houses will definitely carry them, and they show up on Ebay from time to time. The form cutter is mounted on an arbor that's put on the spindle of a mill or a lathe. Some effort should be made to make sure the arbor runs as true as it can, same as with an end mill. It's also possible to make these cutters. Lindsay used to carry (and still does carry, I think) a book on making small gear cutters. The book goes into some good detail on how to make the cutters, how to mount them, and how to use them. It's geared (so to speak) toward people making clock gears, which use a different tooth form than most industrial gears, so you'll have to be aware of that when you're reading it. But it's excellent material. An alternative to form cutters is to use a fly cutter that's machined or ground to the correct form. These are easier to make than the multi-toothed form cutter, so you find this a lot more in the home shop. The cutter is mounted to the spindle using what looks like a fly cutter with no angle on it. The cutter sticks out perpendicular to the spindle axis. The same book from Lindsay that covered multi-toothed gear cutters also covers fly cutters. Jerry Kieffer turned me on to the idea of directly making the cutter on a mill using tool steel. It works. (Thanks, Jerry!) In each case the job of the cutter is to cut the gap between two teeth. So the form of the cutter will look like the space in the gear rather than the teeth themselves. It's pretty obvious but it bears mentioning. Since gears with different numbers of teeth will have drastically different shapes for the gaps between them, one cutter won't cut all gears. Of a given gear pitch, there are typically eight cutters that are used to cut the entire range of gears, depending on how many teeth the gear will have. Once you've got the cutter of your choice mounted on the spindle of a lathe or a mill, it needs to be brought to bear on the gear blank. This is typically set up in a rotary stage or a dividing head. Here's a nice picture of a dividing head setup from Tony Jeffree's web site: http://www.jeffree.co.uk/Images/cdhphoto19.jpg (This is taken from his article on building a comprehensive dividing head for the Peatol/Taig lathe and mill: http://www.jeffree.co.uk/Pages/divheadmk2.html ) Some points to note: The cutter in use is a single point fly cutter that's held in a normal fly cutting head. But if you look at the tool tip, you'll see it sticks out sideways from the spindle axis, not at the angle of the fly cutter. The gear blank is supported in front (and I'd guess behind) with metal plates. The force from the cutter will try to knock the gear blank around. Without support it can definitely flex, and can be permanently bent. The support adds rigidity to the setup. The blank is also mounted on an arbor, which should keep everything very concentric. I don't know the details of the arbor Tony used in this shot, but my guess is there's a boss that's cut to be a slip fit to the size of the hole in the gear blank, and that the nuts hold it firmly against the arbor. For what it's worth, with a setup like this you can bore the hole in the hub, mount it to the arbor, mount the arbor on the lathe, cut the OD of the gear blank (which will then be concentric to the central bore), move it to the dividing head without dismounting it from the arbor, and then cut the teeth. You get a really concentric gear that way. If you take a look at industrial gear cutting machines that use form tools (not hobbing machines or gear shapers), the setup is pretty similar. There's a rotary chuck, just as you said, that holds the blank. Typically this is on an arbor. Often there's more than one blank on the arbor, since the setup time involved in cutting twenty gears is the same as the setup time involved in cutting only one. The cutter is in a spindle that's perpendicular to the axis of the chuck, but offset to one side. The plane of the cutter should pass through the axis of the rotary chuck and not be above or below it. Some books I've found that had good info: [NOTE TO FILE: TOM WROTE SOME OF THE BOOK TITLES AND INFORMATION HERE FROM MEMORY AND CORRECTED ANY DETAILS IN THE NEXT MESSAGE THAT FOLLOWS.] "How to Make a Tool Grinding Attachment" by Robert Porter, available from Lindsay Books -- This is really geared toward clock and watch gears, which use the cycloidal tooth form, but there's a nice bit on how to make a tool that'll make the cutters you need to make the gear cutters, and then a nice discussion on how to use them to make gears. "Clock Wheel and Pinion Cutting" by J.M. Wild, available from Amazon or Arlington Book Co. -- This is a nice book on how to use commercial or home-grown gear cutters to make clock gears. Except for making the cutters themselves, just about all of it can be lifted lock stock and barrel and applied to making involute gears. "Gear Cutting Practice" by Colvin and Stanley, available from Lindsay Books -- This will give you lots of good info on commercial gear cutting machines, including the Gleason hypoid gear cutter, which is WAY off topic from your question. Sorry... "Standard Gear Book" -- It's out of print, unfortunately, but has one of the best discussions I've seen on the involute tooth form. There's also lots of good info out on the web, though it's often hard to dig up. "gear" has too many meanings, and Google doesn't distinguish by context. Not yet, anyway. Do a search on "gear cutting" and you're as likely to hit the Gleason site as you are to hit a clothing fashion site that caters to cutting-edge gear (yo). Hope this helps. Sorry for the rambly reply. I'm about two quarts short on sleep and about a gallon short on caffeine. Tom ---AND Date: Wed, 13 Apr 2005 22:29:04 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Gear Cutting Books Ok, I was dead-wrong on one of my references, so I'm re-posting the lot with them all sitting in front of me: Porter, Robert D. "How to Make a Form Tool Grinding Attachment for the Watchmaker's Lathe for Making Gear Cutters and the Like". Bradley: Lindsay, 2001. Wild, J. Malcolm. "Clock Wheel and Pinion Cutting". Fairfax: Arlington, 1988. Colvin and Stanley. "Gear Cutting Practice". New York: McGraw Hill, 1937. Reprinted Lindsay, 1992. Trautschold, Reginald. "Standard Gear Book". New York: McGraw Hill, 1935. It's that last one I utterly botched, and unfortunately it looks like it's out of print. Turns out Reginald Trautschold wrote another book called "Gear Design and Production: Rules and Working Formulae". I don't have a copy of this one, and it's also out of print, so I might not get that lucky. Wild's book takes a brief look at commercial clock wheel and pinion cutting machines, but also shows how you can do pretty much everything on a watchmaker's lathe as well as on a Myford, so the info definitely applies to tools the size of a Taig. Porter's book really is about the grinding attachment, but he does go into how to use the tools generated by the grinding attachment to make both multi-toothed cutters and constant profile fly cutters. Even if you're not into cuting gears, the grinding attachment is pretty cool. It lets you put a very precise tip radius on a lathe tool, and lets you control the grinding angles really really well. (I need to get off my zud and make this thing.) But unless you build it around a grinder, it means grinding tools on your lathe. Cover the ways!!! Colvin and Stanley's book cover the gear cutting practices in use in 1937. It goes into the various machines in use at the time, the various methos (hobbing and shaping being the most prevalent ones since they can produce gears in bulk very quickly. It also goes into helical gears, herringbone gears, bevel gears, spiral bevel gears, hypoid gears, worm gears, etc. Trautschold's book is the only one I saw that went into the various formulae used for generating tooth geometry for involute gearing. (Both Porter's and Wild's books go into the geometry of cycloid gearing, which is actually pretty straightforward.) One other reference on tooth form before I sign off: Some time after I'd bought and munged through all these books, I found out that Vector CAD/CAM comes with a gear program. You tell it your module or diametrical pitch, the number of teeth, pressure angle, etc., and it spits out a DXF of one tooth and one space for your gear. In CAD you can then generate a polar array around the center of the gear in order to generate the entire gear shape. Using this to get the geometry for the cutter necessary to cut that gear is pretty straightforward at that point. It's a really neat program. Tom ------- Date: Thu, 14 Apr 2005 19:18:56 -0500 From: David Robertson Subject: Re: Gear Cutting Books FWIW... Malcom Wilde has a new book out to replace the old one mentioned in the list above. The new one is around 400 pages vs 40 pages for the one listed. It is a much more comprehensive book. Read about it at [reconnect pieces of address in your browser, no space] http://www.amazon.com/exec/obidos/tg/detail/-/1861262450/qid=1113524258 /sr=1-3/ref=sr_1_3/102-0311673-0947324?v=glance&s=books David ------- Date: Thu, 14 Apr 2005 23:34:04 +0100 From: "John Stevenson" Subject: Re: Re: Gear Cutting > If you haven't seen it already, you might want to look at this: > http://www.metalwebnews.com/howto/gear/gear1.html > I don't know if he ever wrote part two of the article. Martin Sorry No I never did follow up with the second part but if I can answer any specific queries I'd be only too pleased. John S. ------- Date: Thu, 14 Apr 2005 16:31:38 -0700 From: "Larry Richter" Subject: with all the gear questions, some tech ad stuff Everything You Always Wanted to Know About Gears... and didn't know how to ask! Stock Drive Products/Sterling Instruments (SDP/SI) offers a Handbook of Gears, D190, featuring a 138-page technical section prepared by Professor George Michalec, consulting engineer and former professor of Mechanical Engineering at the Stevens Institute of Technology in New Jersey. The handbook features more than 122 tables and illustrations and is divided into 20 major areas including design procedures, standards and application data. And it's all online, either as a pdf file or in html. http://www.sdp-si.com/D190/D190cat.htm Gearing Up. Need a refresher course on gears that's simple, easy-to-follow and even tests your knowledge? How about simple formulas for working out the gear ratio or RPM of a chain and sprocket system? Technologystudent.com has all the answers for gears and tons of other engineering topics. It's all available here. http://www.technologystudent.com/gears1/geardex1.htm New Technical Documents Released. The American Gear Manufacturer's Association (AGMA) recently released several new technical documents - Mechanisms of Gear Tooth Failure, Tolerance Specification for Gear Hobs, Gear Reducers, Gear Sound Manual, and a Design Manual for Bevel Gears. Check them out. http://www.agma.org/new_page.asp?page_name=newtechdocs.html Worm Gears in Your Shop. http://www.atmsite.org/contrib/JSAPP/wormgear/wormgear.html The Internet gives us recipes to make cakes, tips for getting a job, and even how to make your own worm gears on a lathe. The basic procedure, according the Amateur Telescope Makers site, "entails constructing a rigid fixture to hold a blank disk that is free to rotate against a standard tap held in the chuck of the drill press or lathe, which serves as the hob for cutting the teeth of the gear." Check out the details, complete with photos. ------- NOTE TO FILE: And now back to conversations mainly in date order. ------- Date: Thu, 16 Nov 2000 21:44:40 -0000 From: cstaffax~xxhallam.com Subject: Replacing back gearing I just recently finished cleaning gunk off a 6" Craftsman 101.07301, serial 7761. Clausing says it's pre-war(!) One of the previous owners seems to have taken some heavy cuts, as the smaller diameter gears in the back gear train are badly worn, as in about half the tooth thickness is gone. I have to replace the head gear as most of the indexing holes are smashed beyond usefulness; Clausing wants $40.17 for that, which seems about right. But the other two pieces are priced as follows: M6-243A Gear Assembly (comes with bushing installed) $84.21 M6-79 replaced by 2140-10 Pulley & Gear Assembly (bushings installed) $93.75 Which seems a bit much. So I've been thinking of perhaps cutting the ruined teeth off the Zamak castings I've got and pressing a new bored-out gear over top. This seems more likely on the back gear casting; the pulley gear doesn't have much material left around the bore. Any thoughts? Should I save myself headaches and just buy the replacements, or is this (or some other) kluge worth trying? ------- Date: Thu, 16 Nov 2000 16:12:40 -0600 From: "Reger Walters" Subject: Re: Replacing back gearing I don't know where you are getting gears from to press on. If Clausing has to set up and make new gears these prices are cheap. I used to run gear cutting equipment and I am very familiar with the design and cutting of gears. Boston gear is a good scource for replacement gears to modify and use. One suggestion, don't make the press on fit very tight and drill and tap holes on the parting line of the fit and install and loctite set screws at these points to insure no slippage. Three set screws around the periphery would be plenty. Equally spaced of course or close to it. Reger ------- Date: Thu, 14 Dec 2000 14:39:09 -0000 From: "Phil Jaster" Subject: Re: Gears In taigtoolsx~xxegroups.com, acharlestox~xxh... wrote: > Reference Tony Jeffrees lead screw and indexing gear designs. > Where in N America can I find suppliers of small spur and worm gears? > (Small quantities of small bearings too) > Locations in Canada would be preferred! No disrespect to U.S. > brethren, but US dollar bank drafts and Canadian import taxes are > best avoided if at all possible. From Google.com: http://www.google.com/search?hl=en&lr=&safe=off&q=Canadian+websites+ge ars+bearings&spell=1 provides a list of the subject: << Canadian websites gears bearings >> Hope that helps from an American who loved being in Canada! Phil -------- Date: Sat, 13 Jan 2001 12:55:34 -0000 From: "Kevin Kreger" Subject: Re: Change Gears For Craftsman/Atlas Lathe Dave, $212 is a good chunk toward buying a small used mill and dividing head (not that good a chunk, but if you're like me, you're always trying to justify buying new tools!). I've made change gears for my 10" Atlas on a horizontal mill, and recently, on my Taiwanese mill-drill with a single-point, hand ground toolbit. I made them out of Al because I figured steel would be too hard on the existing zamak gears. It was fun and they work fine. Kevin -------- Date: Thu, 18 Jan 2001 07:47:15 -0800 From: "Dave Engels" Subject: RE: Re: Change Gears For Craftsman/Atlas Lathe Kevin Kreger [mailto:kjkx~xxvabch.com] wrote: >>> Dave, Exactly. I ground a hss lathe toolbit until it was a good fit with a change gear. Then I mounted it in fly-cutter made so that the bit sticks out parallel to the table, instead of down at an angle, like most of them. That would be easy to make if you don't have one. I cut the keyways on a shaper, but you could do it quickly with a file. If you're making an aluminum gear, I bet you could rough them out with a coping saw with a wood blade and finish with a file. If you want any more info or if you need any help figuring out the OD for the gear blank, let me know. <<< Thanks, Kevin. Now I've got a project to start on! Clausing wants a total of $336 for all the gears I need, some of the gears they want $38 for. $38 for a die cast pot metal gear!!!!!! So, thanks to your kind advice, I'm going to give it a shot. First I've got to make a dividing head holder that will fit on my lathe (all I have is my little six inch lathe and a drill press) and the fly cutter. That will take me a couple of happy evenings!!! (I love doing this stuff.) Then, I'll take you up on your kind offer and ask you for some wisdom re what the correct OD for the gears ought to be. I'm glad you had good experience with aluminum for the gears, somehow trying to do this with steel sounds daunting. Thanks again, Dave Engels ------- Date: Fri, 19 Jan 2001 02:54:30 -0000 From: loon432x~xxaol.com Subject: Re: change gears list In atlas_craftsmanx~xxegroups.com, ikimjing wrote: > Hi all.Thought I would ask if anybody knew what a complete set of > change gears consists of for a 12 inch? I made a couple of new gears > and figured that while I still have access to a cutter maybe I would > make any that I need.Also does anyone know what I need to cut metric? > I read something about the 127 tooth but dont think that is what I > need.Thanks for your past help,It sure nice to here answers to some > problems I have had. Jim. Hey there! I just read this after being away for a few days. Thought you might be intrested where 127 teeth for metric threading comes from. The ratio of milimeters to inches is 25.4mm = 1". The lowest number that 25.4 will divide into evenly is 127. Since you can't have a .4 gear tooth, 127 teeth is the smallest gear that can be used in a English to metric or a metric to English lead screw gear train. I have a 6" Atlas lathe and I am planning to make a 127 tooth gear for it out of black delrin. I have the material and the cutters on hand, but haven't found the time yet. Oh yeah, what about the size? The standard change gears for the 6" lathe are 24 pitch. The 127 tooth and a mating gear will be 48 pitch. This makes the new 127 tooth gear just slightly smaller than a 64 tooth-24 pitch gear. Hope this helps someone. Terry Looney -------- Date: Thu, 15 Feb 2001 18:55:35 EST From: AtlasTV48x~xxaol.com Subject: Gears I have replaced the gear set on my TV10 with a 1/4 Kevlar timing belt and a series of pulleys for different ratios. It runs beautifully! There is no backlash or slop and it's silent. One pulley on the end of the screw, one on the spindle, and a take-up pulley on the arm. I make the pulleys out of plastic stock with a degree wheel and clamp on the spindle and a motor driven cutter on the tool post. I was making the pulleys for another application when I came up with a requirement to cut a thread pitch that I was missing the gears for. Since this is a non-atlas modification like the surplus treadmill motors, please respond offline if anyone wants more information of avoid the wrath of the off topic police. Dave ------- Date: Wed, 11 Apr 2001 05:05:05 -0000 From: rocketsmithx~xxnetzero.net Subject: Gear Tooth Repair The other day I was buying an old South Bend 3-jaw chuck from a gentleman-machinist at a flea market, and we got to talking, knowlegable old-timer to eager new kid(me), and when I told him I had an Atlas lathe, he immediately asked me if I knew how to repair broken gear teeth? I said he was knowlegable didn't I? I said I did not, and he proceded to tell me how it's done: It seems he had to perform this type of repair on a lathe some years ago, that used some kind of pot-metal change gears. He proceded to drill three tiny holes where the gear tooth had been, and inserted three pieces of steel wire- actually small finishing brads- which he then cut off to the correct height sticking out of the gear for a tooth. He then applied JB Weld to the wires to provide material to build up the tooth. As the JB Weld began to cure, he rolled the gear "tooth" through the meshing teeth on an adjacent gear, to provide the correct shape. As far as he knows, the gear is still in use. On another occassion, he had to perform a similar repair on a sawmill drive gear. The mill had ordered a replacement gear that would not arrive for 2 days, and the mill was looking at seriously expensive downtime. This time, the size of the gear teeth meant using 3 spikes to provide the "spine" of the new tooth, but the same JB Weld was used the same way. When the new gear arrived, the mill owner decided not to replace the repaired gear- to avoid the downtime required, so the gear was used for the next 5 months until the mill shut down for the winter. The repaired gear is now the spare, in storage for future use if needed. He said make absolutely sure the area to be repaired is ***CLEAN*** for this repair to work. It sounds like this should work on zamac as well. Hope this helps anyone with broken gears. Jeff Hayes ------- Date: Wed, 11 Apr 2001 08:04:57 -0700 (PDT) From: "J. Reid" Subject: Re: Gear Tooth Repair I used the same idea to rebuild a bunch of teeth on a small gear. Made a pattern using RTV rubber from the good teeth. then cast new teeth using epoxy filled with brass powder. JB weld would work too. When I had a duplicate gear so I could make a complete mold I used the hub from the damaged one to make a completely new one. JAck J. M. Reid Issaquah WA ------- Date: Thu, 12 Apr 2001 14:36:13 -0700 From: S1 Subject: Re: Gear Tooth Repair JB weld is a metal epoxy. It comes in two tubes: Part A and a Part B. Take a piece of scrap material and mix equal proportions of A and B. Clean the parts to be fixed and apply the mixed JB Weld to the broken area. Let set up 24 hours. I've seen JB Weld at Home Depot, Hardware stores, HQ... I have some which I used when I cannot weld/braze/solder the pieces together. I made this part of Iron, with an aluminum top piece and because you cannot use any means of welding to stick these metals together, I had to use JB weld to put the part together. JB weld deosn't give you as strong a join as silver solder, brass or a weld so I only use it when there is no other means of sticking the metal together. For "white metal" or Zamac thread cutting gears, fixing as Jeff wrote seems to be the best way because I wonder what is in "White Metal". It gums up taps/dies, is really soft and cannot be put together the way respectable metals (like brass, for example) are. JB weld is probably stronger than the "white metal" itself. Gabe ------- Date: Thu, 12 Apr 2001 14:28:42 -0700 (PDT) From: Don Smith Subject: RE: Re: Gear Tooth Repair- JB Weld Dave, if you really want to make the JB Weld tough, stop by an auto repair place that has a brake lathe, and "borrow" some metal dust and mix it with your JB Weld. Regards, Don Smith ------- Date: Fri, 13 Apr 2001 16:35:57 -0400 From: Jude Miller Subject: Re: Re: JB weld gears Nick Hull wrote: > If JB weld is stronger than Zamak, someone needs to CAST gears out of JB > weld. It should be EZ to make a form if you have a good gear, and > considering the prices of gears ahould be a real money maker. Matweb lists Zamak 2 a.k.a. Die Casting Alloy Number 2, as Al 4% Cu 2.5% Mg 0.04% Zn 93.5% Tensile strength is about 52,000 psi! Hardness HRB 63. This is not a lot less than 1018 steel (65,000 psi, HRB 73). Best, Jude Miller ------- Date: Fri, 13 Apr 2001 18:27:28 -0500 From: "Bennett Benson" Subject: RE: Re: JB weld gears JB Weld's website lists the Tensile Strength: 3960 psi - quite a bit less than Zamak. No numbers listed for hardness though. Bennett Benson ------- Date: Wed, 16 May 2001 08:49:08 -0700 From: "Nicholas Carter and Felice Luftschein" Subject: Subject: Tumbler Gears On Atlas 12" Lathe I had to make replacement gears on my 10" due to wear and breakage by previous owner (who lubricated the gears with stiff grease and sawdust, apparently), I made mine of moly-filled nylon, and they are very quiet, at least compared to the other gears that I need to replace. http://www.cartertools.com/nfhome.html ------- Date: Wed, 16 May 2001 22:38:37 -0500 From: "J Tiers" Subject: Re: Re: Tumbler Gears noise Dunno about Atlas, but the leadscrew drive change gears on my Logan are pretty loud at above 500 rpm spindle speed. The change gear train, and hence also the gears which drive the QC, are not usually made to close tolerances, and are usually run a bit loose. Plus, they are spur gears, which inherently make a lot of noise anyhow. Jerry ------- Date: Mon, 11 Jun 2001 17:47:49 -0400 From: "Mac Goekler" Subject: Re: making plastic gears [sherline group] >My gut reaction is that maybe Delrin would stand up alright, but it may depend on the valve spring stiffness. What about connecting them using a small reinforced toothed belt like a miniature supercharger belt? I think they use them alot on the small R/C race cars. Keith Yundt < Hi Keith, Delrin (Acetal from Dupont) has as one of its main uses -- molded gears. In my working days we made millions of them. One of its main claim to fame is -- it is somewhat self-lubricating. The design spec. for plastic gears is a little different (backlash, clearances, etc.) than metal, but for a small gear it will not be an issue. UHMW (PE) -- Ultra High Molecular Weight Polyethylene deforms more than Acetal -- I would use the Acetal. Please remember when making cutters for Acetal -- plenty of rake. Acetal works OK with pure oils/greases (avoid solvents). Good luck, Mac from Ohio ------- From: deanwx~xxvalint.net Sent: Monday, June 11, 2001 7:46 AM Subject: [sherline] making plastic gears Hello to the group: I'm building a small gas engine with a bore of 3/4" and 1" stroke. The maximum speed should be about 600 rpm. I have some nylon and UHMW plastic stock on hand, and am wondering if either of these is suitable for making the timing gears. They are 48 pitch, one 20 tooth and the other 40. They will drive the exhaust cam and valve. Intake is atmospheric. Are these plastics tough enough for the job, and if so will they be affected by lube oils? Any suggestions or comments appreciated. Thanks Dean W ------- Date: Mon, 11 Jun 2001 16:58:31 EDT From: wlindiii53x~xxaol.com Subject: Re: making plastic gears In general, UHMW (though very impervious to chemicals and oil) is too soft for the application. Nylons (especially type MC901) make excellent gears but will absorb some oil, just as they readily absorb water, so some swelling may occur. Why not use brass and not have to worry about it? Hope this helps ------- From: "Reid" Date: Mon Jul 23, 2001 4:55 pm Subject: making gears on plastic I would like to make some plastic gears for robots. I have some small stepping motors with gears. I need to make bigger gears that match teeth which on stepper motor. I don't have any experience to make gears. I understand we can cut gears with rotary table and fly cutter. Can someone tell me where URl that we can learn how to make gears? I have a mill, rotary table and flying cutter. I hope that all we need to make gears. Reid ------- From: "John Shadle" Date: Tue Jul 24, 2001 8:18 am Subject: Re: making gears on plastic On my websites you can find an article I wrote on making flycutters. You can download it from my websites, free. John Shadle PO Box 385 Minatare, NE 69356 http://www.geocities.com/jshadle.geo/index.html http://www.scottsbluff.net/~ticktock/index.html ------- From: "Al Lenz" Date: Tue Jul 24, 2001 10:35 pm Subject: RE: [sherline] Making gears >> (snip) There is a method described in MODEL ENGINEER magazine that uses two circular disks arranged into a cutter that is used to make a tool which is used to make the gear cutter. Its much to long to explain here, but ME publishes a book, one of the WORKSHOP series #17 called GEARS AND GEARCUTTERS. AN excellent book if you want to know all about gear making in the home shop. ron ginger << Here is a link to a good description, written by John Stevenson, of how to make a button type form cutter: http://www.metalwebnews.com/howto/gear/gear1.html The book referenced by Ron is indeed excellent, but may be hard to find. More info on book: Gears and Gear Cutting by Ivan Law. Published in England by Nexus Special Interests Ltd, ISBN 0 85242 911 8 Hope this helps, Al Lenz ------- From: wjw2000... Date: Thu Jul 26, 2001 11:45 am Subject: Re: Making gears I saw a demonstration of way to make gears at the NAMES expo a couple of years ago, and have also seen this method in one of the Village Press puplications. First a tool bit is ground to the "rack" profile for the pitch and pressure angle required. (A "rack" is a straight rod cut with angular teeth that match the desired gear.) This would be simply a pointed tool with straight sides angled at either 14.5° or 20° as required, and a blunt nose. Next, a shaft of convenient diameter is prepared as a gear cutter, and several grooves are cut into it using the tool bit. The groove spacing, depth, etc. must match that of appropriate gear rack. This information can be found in the Machinist Handbook, or other reference books. Note that the tooth spacing will end up being some multiple of PI. Best to use a calculator when determining the spacing, and do not round off the numbers. Flutes are cut lengthwise so that the cutter resembles a regular tap. The gear blank must be "indexed", as described for making gears with a fly cutter, and the cutter is applied in exactly the same way as would a single point tool. The difference is that with each increment of the blank rotation, the gear tooth profile is "developed" on adjacent teeth. Of course, this will be an approximation of the true involute form, but it should work. I have an idea for an improvement on this technique. The cutter blank could be held in a 4-jaw chuck and offset from center by some depth, say the depth of the gear tooth. The diameter is turned down until you have a cylinder that will be offset from the center of rotation of the un-machined part held in the 4-jaw chuck. It will be sort of like a cam or crank shaft. The grooves are machined as before to make a "circular rack". Then, a single flute is milled across the grooves, so that if viewed from the end, the edge of the groove is at the "highest point" of the "cam". This will provide a cutting edge of proper form, and back relief. Perhaps it might be better to mill the flute BEFORE cutting the grooves so that the burrs will protrude into the flute and be easier to remove without damaging the tooth form after hardening. ------- From: RODRIQUJ... Date: Thu Jul 26, 2001 5:02 pm Subject: RE: [sherline] Re: Making gears I have produced a four hour video covering gear making and all of the HOB gear cutting techniques. Saves a ton of $$ over the use of involute gear cutters. I make single tooth cutters, a straight hob, a spiral hob ( like the industrial ones ) and one to cut worm gears. I not only cover their manufacture on the video, I also proceed to put them to use to make a change gear for a lathe, a spur gear large ans small, and two methods for making worms and workm gears. Did you know you can make great gears with only a large diameter TAP?? It cost $38 + $3.95 S/H. I market this and over 11 other miniature machining titles. Info on all can be found on my site at: http://www.homestead.com/tool20895/jose7x10taig.html Thanks Jose ------- Date: Sat, 2 Feb 2002 22:53:46 -0600 From: "Dallas Shell" Subject: missing lathe change gears For the times when you need an oddball change gear or when you have one missing, there was a method of making a usable gear described in Projects in Metal or Home Shop Machinist several years ago. The gear was made by first making a gear blank out of wood, drilling the shaft hole and filing a keyway in the wood. The wooden blank is made to have an outside diameter equal to the diameter of root diameter of the needed gear minus 20-40 thousandths. Then using the existing gear train on the lathe running at a slow speed, a long piece of brass shim stock (10-20 thousandths) trimmed to the width of a gear is fed in-between a pair of moving gears (moving very slowly). This will form the brass with the proper gear tooth shape. After enough length of shim has been formed to have enough teeth for the needed gear, the brass is cut to the required number of teeth plus one. This brass with the tooth pattern is wrapped around the wooden blank, overlapped one tooth, and soldered together. The wood with brass wrapped around it is then laid down on wax paper and the space between the brass teeth and the wood is filled with body putty, epoxy or fiberglass resin and allowed to harden. After drying, the new gear is trimmed up of excess epoxy etc and is ready for use. I have made a couple of these and used them quite a lot while I was looking for some change gears that I needed for one of my lathes. Dallas Shell 6in Atlas 9in Southbend ------- Date: Mon, 11 Feb 2002 17:26:16 -0700 From: "JOHN & SALLY DETWEILER" Subject: Epoxy Gears Hello to all. I've had some luck making a copy of a 109 change gear out of Epoxy. I've been testing the gear for hours under various loads and it seems to be holding up very well. The A-3233-24 tooth gear I made is on the forward reverse lever and in mesh with two original metal gears. Obviously, an Epoxy gear won't be as strong as a steel gear, but it seems to perform quite well. I will explain the process and ask for suggestions for improvement. I pressed a 1/2 inch roll pin through the gear being copied so the pin protrudes about 1/2 inch through the gear on one side. I filled the bottom of the roll pin with silicone sealant as well as the two key-ways in the gear and let the sealant cure. The gear and pin are then sprayed with silicone mold release spray. I used a small plastic bowl about 3 inches in diameter to hold the plaster. The bowl is also sprayed with silicone. Set the gear and pin in the bowl with the 1/2 inch protruding side of the pin down. Approximate the level of plaster needed to reach the top of the gear and mark the bowl at this level. I used a product called "Faster Plaster" . Mix the plaster per instructions on the bottle and pour into the bowl to your mark. Tap the bowl on the table to settle out bubbles and level the plaster. Insert the gear and pin into the plaster and again tap the bowl on the table to work the plaster between the gear teeth. You can add or remove plaster to obtain a level just slightly below the top of the gear. Don't pour above the top of the gear, or you won't be able to remove the gear without breaking the mold. This plaster sets rather fast, (5 to 10 minutes). Don't put a metal gear in the microwave! The plaster is microwavable to increase it's cure speed, but NOT with metal inside. After the plaster sets at room temperature, place the bowl in a regular oven on "warm" for about an hour. After cooling, remove the plaster form from the bowl. This next part is tricky. I made a tool that just fits inside the roll pin to drive it out. Tap the roll pin while holding the plaster form to loosen the gear from the plaster. I've had problems with the plaster chipping at the top of the mold, but have been able to repair the damage. I'm experementing with pouring in layers and trying different matterials to eliminate this problem. Also, big gears get stuck in the plaster and the mold can't be saved. Forget about "instamold", it shrinks and dister the gear is removed I installed a 1/2 steel dowel in the hole left by the roll pin. I used the shank of a 1/2 inch drill bit for the dowel. Again spray the gear mold and dowel with mold release. The epoxy I used to make the gear was 3-M structural adhesive part 3501, a two part equal mix Epoxy. Use a putty knife to force the Epoxy into the mold, especially into the gear teeth. Let the Epoxy flow to a level just above the top of the mold to ensure a full width gear. When the Epoxy has cured for several hours, it will be of a hard rubber consistency. The whole thing can go in the oven on warm for several hours to speed up the curing time. When the Epoxy is mostly hard you should not be able to dent it with your fingernail. Drill holes through the palster around the gear to control fractures when breaking the mold. The dowel pin is pressed out of the new gear, leaving a perfect diameter and perfectly located hole. The excess Epoxy is sanded off the top of the gear. The gear should be cured in the oven for several more hours free of the mold. The keyways must be filed into the new gear. I am only using the gear as an idler in the forward reverse gear train and didn't require the keyways, just press in the bushing. Be sure to test the gear by hand cranking the spindle gear. Slight filing may be necessary. The 3-m Epoxy is expensive, and hard to find. I'm experimenting with "JB-Weld" and other epoxies. Any ideas? A hard rubber mold that doesn't shrink would be most useful and would alow for re-use of the mold and the reproduction of larger gears. I'm open to suggestions. The most frustrating part is chips at the top of the mold, but the final gear can be filed to correct the problem. If we can all figure out a foolproof method of reproducing these gears, evryone can get the gears that he or she needs without costly machining. If you try this method, just be very patient and make notes of what works best for you. I'll keep in touch with my progress. I can't post a photo here, but if you want to see a photo of the mold please write to detweilersx~xxmsn.com and I'll send a photo. Happy machining! John ------- Date: Mon, 11 Feb 2002 20:30:13 -0600 From: "Randy" Subject: Re: Epoxy Gears John: Try this site for molding materials: http://www.alumilite.com/ I think if you will give them a call they may be able to help with the small problems you are having. I really see no problem using epoxy gears unless you would have crashes that would lock up the leadscrew. Randy Pedersen ------- Date: Mon, 11 Feb 2002 21:40:21 -0600 From: "jerdal" Subject: Re: Epoxy Gears > I've had some luck making a copy of a 109 change gear out of Epoxy. Another suggestion would be to make the mold out of the rubbery metrology casting material, I think it is used for exactly this sort of reproducing purpose, as obviously it is harder to mike a piece of rubber. Or make a mold using Cerrosafe metal (melts at about 160F) which can be cast around the gear, the gear removed, and the epoxy poured in. The metal can then be melted away from the cast gear in hot water, and re-used. Both methods will make a gear including the center hole and even a keyway, if you think (I don't) that the epoxy can stand it. In any case, several places like Small Parts Inc or even Enco have possibly suitable materials. Jerry ------- Date: Tue, 12 Feb 2002 15:44:29 -0000 From: "throwawaytip" Subject: Re: Epoxy Gears There should be no problems with the resin gearing. My Atlas has had some non metallic gears for about 5 years. I machined mine from phenolic resin board, Micarta is the brand name of the material, probably the resin you are using will last just as well. The resin wears well in low power applications, especially when paired with bronze - I run a small bronze gear with a large Micarta one. Another advantage of non metal gearing is quiet running at high speeds, something the original die cast gears were not good at. Casting the teeth is a great idea - as long as the master used for the mould is in good shape - by the time I bought my lathe all the die cast gears were starting to show profile deterioration. Regards, Alan S. ------- Date: Tue, 12 Feb 2002 10:21:19 -0800 From: "Bob May" Subject: Re: Epoxy Gears I'd rather use Hydrocal or dental plaster for this job. These plasters are waterproof types and can be used for metal casting if needed to for many of the low temp metals (brass is a bit too hot tho). The part can be pulled out while the mold is still wet and you can even cast in the center part if desired. A bit of experience with those plasters will show that just as soon as the plaster is solid the part can be pulled without problems. The surface provides a light film of water to allow stuff to move. I haven't sat down to actually do a gear but have used these plasters for a lot of other things and know that you can do gentle carving with them just as soon as they start setting up and that the carving gets harder as the setting proceeds. I might also note that good straight pulls (like from a drill press or mill pulling up) will insure that the corners won't get damaged. Another note, if you ever pour a metal into a plaster mold of any kind, make sure that the mold has been at a temp over the boiling point of water until it's dry of any entrained water or you will have a serious problem of metal and plaster all over the place and that includes down anything you are wearing. Bob May NEW! http://bobmay.astronomy.net p.s. The Cerro company makes several different blends of the cerroXXX metals. Some of them have a positive expansion while others have a negative expansion over temp. There are several that are in the near 0 expansion rate which is probably what you want. ------- Date: Tue, 12 Feb 2002 19:56:27 -0600 From: "jerdal" Subject: Re: Epoxy Gears The "Cerrosafe" is the 157-190 melting material, which is almost exactly zero shrink at 1 hour. It is used for metrology casting, such as rifle chambers. For most gears, the 2 or 3 thous movement of any of the series should not be an issue, though. Jerry ------- Date: Tue, 12 Feb 2002 20:48:24 -0700 From: "JOHN & SALLY DETWEILER" Subject: Epoxy Gears Thanks to everyone for all the great ideas and info! I found 25 lbs. of dental plaster for only $ 14.25 They have fast, medium and slow setting. I guess I should try the slow setting? For the missing gear, I think I'll try the shim and wooden disk method and cast a mold of the new gear if it works out. I have to check on the gear number and get someone to send the root diameter to me. I made another 24-tooth gear out of JB-Weld Epoxy... so far so good. Someone needed a spindle gear for a 109 lathe as I recall. Maybe I can make one for you. Thanks again to everyone for all the help! John 109 ------- Date: Wed, 13 Feb 2002 16:34:04 -0000 From: "stevenhkb" Subject: Re: Epoxy Gears-Vacuum bubble removal John, thats a great post! I would recommend you think about some kind of vacuum removal of bubbles, it helps and isn't hard to do. I have done some epoxy bedding of firearms, and vacuum the epoxy to remove mixing bubbles before use. Reduces voids. If you try that with both the plaster and epoxy it will help. I have a dedicated vaccum pump, bought from Surplus Supplier(? the one in Nebraska) for about $35 many years ago, a GAST brand used for medical vacuum, they are also used in copiers to pick up paper sheets. Mine was 220V, a minor inconvience. However, you will get a lot of help from just a home or shop vacuum as they will do some good. Make a plate of wood (I used a plastic coated shelf from Lowes) with a rubber sheet glued to the top and a pipe thru to the vacuum source, and a large glass bowl for a "bell jar". I had to grind the rim flat on carborundum(SP?) sheet to get a good seal. It foams up a lot as the bubbles expand, so allow for that when you do it. Steve ------- Date: Thu, 14 Feb 2002 19:30:06 -0700 From: "JOHN & SALLY DETWEILER" Subject: Epoxy Gears Dental plaster rules!!! It took a few tries, but I made a perfect mold of a 24 tooth gear. Then I made a 64 tooth gear. The 64 tooth mold had just a couple of small chips at the top of the mold. In a perfect world, all gear teeth would be exactly parallel. But slight angles between teeth equate to a wedge effect when removing the gear from the mold. No big deal, chips are just a little bit of filing between gear teeth on the final product. The dental plaster works well. (thanks for the tip!) I let it sit for about ten minutes after the initial set. It sets initially in about 5 minutes. Slight wiggling and pulling breaks the gear free of the mold. Often the gear moves out about 1/3 to 1/2 way and sticks due to slight defects in the gear. Usually chips happen on adjacent teeth. I cast the 64 tooth gear out of JB-Weld epoxy. It turned out great. It takes some time to sand off the excess epoxy on the top of the gear, and to remove the plaster from between the teeth. I suggest wet sanding to reduce dust. I used 60 grit paper. I just need to file the key-ways and bake it in the oven for a couple of hours and it's ready to try. It's well worth the time to make these hard to find gears. Thanks again for all the help everyone! John ------- Date: Sat, 16 Feb 2002 10:54:11 -0700 From: "JOHN & SALLY DETWEILER" Subject: Epoxy Gears Don't use JB-Weld for casting gears....it's not strong enough. The Scotchweld 3501 works best. I was trying out my new gears and when I tightened the screw on the change gear spider, the spider cracked. I tried to weld it and it just cracked in another spot. So I guess I'm done with my lathe projects. Thanks to everyone for the input. Wish you all the best. John ------- Date: Sun, 24 Feb 2002 08:49:26 -0500 From: "Bill Rutiser" Subject: Re: Re: 31-tooth CNC'd Sherline gear > I have a similar variation I have used once in the past to cut a gear > profile on a part. I simply took the tooth profile from the cad file > and turned it into a hss drill blank and then ground part of the > blank away to make a cutter which I hardened. This worked very well > for my application, I made 5 of these parts for engineering > prototypes. you can have a closer look at: > http://www.grifftek.com/images/misc/machined_parts/trojan_gear/trojan_ > gear.htm Regards Bill Griffin Bill, can you elaborate on the process for annealing, turning, and rehardening the HSS drill blank? How complicated is your heat treating equipment? Bill Rutiser ------- Date: Sun, 24 Feb 2002 15:11:06 -0000 From: "bilg63475" Subject: Re: 31-tooth CNC'd Sherline gear Bill: This was something just done on the fly, I have no heat treating equipment (other than a torch) at all. I simply anealed the drill blank by heating it with a propane torch till it was a light reddish coloroed (just started to glow) and then let it cool slowly. After it cooled, I simply machined it and ground the relief in the end. after machining and grinding I heated it with the torch to just glowing and dipped it in some oil to quench it. This seemed to work quite well for my application, I know it hardened the piece beause the first tool I made was not hardedned this way and I didnt get 1 blank machined. WIth the hardened one I machined 4 or 5 pieces and the tool is stillintact. YMMV Regards Bill Griffin ------- Date: Wed, 27 Feb 2002 07:11:21 -1000 From: Herman Subject: gear info BB Ran across a neat forum for info on gears: http://www.communitypc.com/wwwboard/wwwboard.html Herman ------- Date: Mon, 11 Mar 2002 19:41:46 -0500 From: ron ginger Subject: Re: Gear cutting About the cheapest Ive seen involute gear cutters is $25 each. Note it takes 8 cutters to have a full set for any ONE size gear pitch. I lucked out once in a junk yard and got a couple dozen for $5 per POUND. It did take an hour or so to dig thru the dumpster they were in. You can make a very servicable cutter yourself There is a series in Model Engineer magazine, and a book re-print of it that is still sold. The book is cleverly called GEARS AND GEARCUTTING. The basic idea is to place two round disks into a holder where the diameter of the disks and spacing is carefully calculated to make the right tooth form. You make this tool, then use it to make the tool you use to cut the gears. Hobbing can only be done on a hobbing machine- it requires the hob and the gear blank to be linked together with the proper gear ratio. There have been published plans for this, but that would be a serious project. There is a technique in a Unimat book by Rex Tingey, published in England, that uses a form of hob that is still indexed one tooth at a time. The benefit is the hob is rather easy to make and just one is needed for any DP. This is NOT the industrial form of hobbing. ron ginger ------- Date: Mon, 11 Mar 2002 16:05:58 -0800 From: "yasmiin" Subject: RE: Re: Gear cutting Actually for small hobs you don't need to link them together with gearing. The hobs are cut so that they will pull the blank forward as they cut the tooth. Actually they are cutting several teeth at the same time at different depths. The deepest being when the tooth is top dead center. You don't need a special machine to do this. You just have to go slow and be careful. I have about 75 hobs all of which are less than an inch in diameter. Yasmiin ------- Date: Sat, 30 Mar 2002 18:33:17 -0000 From: "jimdlewis" Subject: Gear friction Anyone experienced in gears? I'm building a gadget that has several delrin gears (1" to 2" diam., 1/2" thick) on polished steel shafts (3/8" diam.). Loads vary around 10 to 100 lbs. I'm losing about 50% of energy somewhere in friction. Is the loss likely in the teeth or the shaft contact? Greasing the shaft helped a little but not much. Adding a brass insert to the gears did not seem to help although I only tested it on one gear. I'm also thinking about a Teflon insert. I could redesign for ball bearings at each gear but that would up the design cost. Any ideas? Thanks. Regards, Jim http://www.emachineshop.com ------- Date: Sat, 30 Mar 2002 21:01:00 -0000 From: "toddfoh" Subject: Re: Gear friction Jim, I have a bit of experience with gears, having designed a miniature gearbox for a robot a few years back. Some loss of efficiency is normal in a geartrain. How much depends on a number of factors, the major ones being the types of gears, and the number of gear meshes in the train. But, 50% loss sounds excessive. This kind of loss sounds like some sort of binding. You should assemble the gearbox (if possible) and test each shaft independantly with no mating gears. Each should be as free as possible. But, it sounds like you have already looked at the shaft mount bearings. The second thing to check is the center to center distance between mating gears. A common mistake is to mount mating gears too close together in an attempt to eliminate backlash. In a properly designed geartrain, mating gears have only a single point of contact, on one side of the tooth only. If the center spacing is too close, the meshing gears contact on both sides of one of the gear teeth. In this case, friction losses skyrocket. This is why it is normally impossible to have "zero backlash" without specially designed (split and springloaded) gears. Clearance in highly precise gears may be very small, but these are very expensive. These types of tolerances are not possible with plastic gears. Especially not delrin, which is a fairly dimensionally unstable plastic. In most power transmission applications trading backlash for efficiency is not a problem. In automobile transmissions or the gearbox driving a helicopter blade, efficiency is much more important than backlash. In servomotor gearboxes used in a closed loop control system, however, backlash can be a killer. In that case, antibacklash gears might be used with a bigger motor to overcome the added friction. Or a harmonic gear reducer might be used. Good luck diagnosing your problem. Todd F. ------- Date: Sat, 30 Mar 2002 23:13:55 -0000 From: "jimdlewis" Subject: Re: Gear friction > You should assemble the gearbox (if possible) and test each shaft independantly with no mating gears. Each should be as free as possible. Hi Todd, thanks but in my case I can't do that. > If the center spacing is too close, the meshing gears contact on both sides of one of the gear teeth. In this case, friction losses skyrocket. Thanks for the good suggestion. However I just came back from the garage to try adjusting the backlash and it does not seem to be the problem. Regards, Jim -------- Date: Wed, 31 Mar 2004 09:42:38 -0500 From: Steve Ross Subject: Re: Gear friction >Anyone experienced in gears? Jim, I build clocks so I know a little about your problem. First you need a little tolerance in the pivot hole. Often newbies make the holes too tight. Also you need a little side play for the shaft. I am willing to bet you will have very little loss after these corrections. Steve Ross ------- Date: Mon, 8 Apr 2002 00:55:19 +0200 From: "Pavel Korensky" Subject: Pinion cutting with Sherline mill ??? Hello, I have one question about cutting gears and pinions with Sherline. The situation is as follows. I need to make couple of gearboxes for small motors. Nothing fancy, just simple 1:40 reductors with spur gears. I designed the gearbox and now, I want to cut the gears. I have the complete sets of involute gear cutters (module 0.5 and 1) which I used in the past on the Sherline mill without any problems. For the gearboxes, I need to make spur gears with 25 teeth and pinions with 10 teeth. Everything is module 0.5. The 25 tooth gears are simple. But pinions are another question. According to the Machinery's Handbook, the gear cutter Nr. 1 (in module system) is used for cutting gears with 12-13 teeth. But I need to to cut pinions with 10 teeth. Can I use the Nr. 1 cutter for this job ? Or is it necessary to use some special cutter for pinions ? Thx for any info PavelK P.S. Gearboxes are for a small DC motors and there is no need for super precision. I can accept noise, shorter life of gearbox, backlash etc. I just need to make them as cheaply as possible, because I will need six of them. ------- Date: Sun, 7 Apr 2002 22:17:29 -0700 From: "Marcus & Eva" Subject: Re: Pinion cutting with Sherline mill ??? Hi Pavel: The reason the gear cutters don't go down to ten tooth is that the pinion teeth become very weak with less than 12 teeth. It is because the involute profile becomes severely undercut at the tooth root. There are two ways to overcome this problem. The first is to select a gear profile with a large pressure angle. The second is to use a stub profile with a reduced dedendum for the pinion, and the corresponding reduced addendum for its mating gear. Both require special cutters which makes doing it the "correct" way very difficult. If you try to use the gear cutter that you have, the profile will be wrong for true rolling action between the gear teeth, and you will have teeth that are weak at the root and at risk for breaking off. I would not expect very good performance from what you are trying. The only way to find out though, is to try and see if it is as bad as I predict. There is a way to make a gear cutter that will work very well for this special tooth form. I make a rack type cutter with a big pressure angle (something like 30 degrees), and use a special milling procedure to cut the teeth. The procedure consists of taking a pass around the blank with the rack cutter, then rotating the blank 5 degrees, dropping the rack the correct amount, and going around the blank again. Then the blank is rotated another 5 degrees, the rack is dropped the correct amount again, and the teeth are recut again. The process is continued until you've gone one tooth increment of rotation in 5 degree steps.(in your case 36 degrees) I have a spreadsheet to calculate the cutter geometry and the blank geometry. It also calculates the correct stepdown for the rack. You're welcome to a copy if you want to try it this way. Cheers Marcus P.S. I forgot to ask...are these involute gears or cycloidal gears. My method will work only on involute gears. The "sheet" is actually a program in Microsoft Excel. I can pull it off my computer at work and email it to you if you still want it. ------- Date: Mon, 8 Apr 2002 20:33:25 -0700 From: "Marcus & Eva" Subject: Re: Pinion cutting with Sherline mill ??? Hi Pavel: [AFTER REPLY THAT THEY ARE INVOLUTE TYPE] Please find attached, the gear calculating program. I've set it up for 0.5 module and ten teeth; you can edit anything in red. It will spit out all you need to know to cut a standard spur gear. You will need to make a cutter; I always grind mine from a thin slice of HSS. (I have a surface grinder.) It is possible (and not too difficult) to make one from oil hardening drill rod. I usually put about 4 or 5 teeth on the rack. You can use the same rack cutter to cut any number of teeth of the same module (or DP) Cheers Marcus ------- Date: Wed, 05 Jun 2002 21:28:08 -0000 From: "throwawaytip" Subject: Gear hobbing on a lathe Recent post asked about hobbing gears on a lathe. Here are my experiences. Before I got a vertical mill I used both hobbing and form cutting on various lathes, one of which was a 10" Atlas. Hobbing gears, in this case 20 DP spur gears, was done using the "free hobbing" technique. This involves driving a helical hob on an arbor between centres and carrying the gear blank on the compound slide set over to the helix angle of the hob. The blank is free to turn on an arbor, having been first prepared by gashing it to an approximate tooth form and for the desired number of teeth. The gashed blank is then fed into the hob which, due to its helical shape, turns the blank as it generates the involute tooth profile. I cut several gears in both steel and bronze for a tumbler reverse I was adding to a lathe. However, I got much better surface finish using involute form type gear cutters since there was a certain amount of drag on the tooth flanks using the free hobbing technique. Mostly due to the hob not having been relieved on the flanks - it was home made from water hardening tool steel. I have also cut teeth on worm wheels in the lathe using a similar technique with the exception that the blank is fed directly into the hob as opposed to being fed over top of it. This is a much easier setup than doing spur gears. -------- Date: Mon, 05 Aug 2002 08:07:32 -0500 From: jrw Subject: Re: Re: A new direction....Myford Change Gears [Metal_Shapers group] Gear -- My Cholchester/Clausing lathe has one of the gears in the train made from a linen (Canvas) base phenolic resin material. It has held up well for the last twenty years. There is no need for an exotic material in a lathe gear train. Joe Williams ------- Date: Mon, 05 Aug 2002 09:52:35 -0700 From: Keith Green Subject: Re: Re: A new direction....Myford Change Gears That stuff is known (to me at least) by the trade-name of "celeron". I work in a gear shop and we still use that stuff. Not very nice to work with (dust), but seems to make good gears. keith. ------- Date: Mon, 05 Aug 2002 19:54:22 -0000 From: "volzmechatronic" Subject: Re: A new direction....Myford Change Gears Joe-- Tufnol doesn't appear to be exotic--it's a phenolic fabric laminate similar to that used in your Colchester, and there is a good possibility that yours could be Tufnol: both Tufnol and your Colchester share identical nationalities. See the specs on the Tufnol laminate for gears: http://www.tufnol.co.uk/manufact.htm and see if you don't agree. I'm looking for a distributor/retailer--small and reasonably priced quantities--in the USA, preferably in Houston or at least in Texas. Tom (Msg #1489) suggested that I contact http://www.ilnorplex.com which I have yet to do. Another question: to machine a plastic laminate disk using a mill and a circular involute cutter, should the laminate disk be sandwiched between two, perhaps aluminium, disks to preclude chipping at the outer edges of the cut gear teeth? ...and a suggested starting surface feet per minute for the HSS cutter?? Art (Houston ------- Date: Mon, 5 Aug 2002 15:15:33 -0500 (CDT) From: Tom Benedict Subject: Re: Re: A new direction....Myford Change Gears > Tufnol doesn't appear to be exotic--it's a phenolic fabric laminate Have you checked the local plastics distributors? A while back I paid a visit to Regal Plastics here in Austin, and I coulda hadda sworn they said they carried linen phenolics. Hey, turns out I still had one of their cards. They don't have Tufnol, but they carry a linen phenolic called "LE". Regal has a Houston office, too: 713-957-8541. (And no, I'm in no way affiliated with Regal. It's just my closest source for Delrin.) > should the laminate disk be sandwiched I'd definitely sandwich it with something. The times I've cut linen phenolics, they were chip-happy. Can't say about surface speed. It's been years since I cut any, and I was very very green at the time. Tom ------- Date: Mon, 05 Aug 2002 16:43:00 -0400 From: Tom Wightman Subject: Re: Re: A new direction....Myford Change Gears Small Parts carries phenolic impregnated linen laminate sheet in thicknesses from 1/8 to 1/2. http://www.engineeringfindings.com/cat22/cat22pg77.pdf It ain't cheap. A 6" x 12" sheet of 3/8 thick is $31.05. Still, you could probably get a few change wheels from that size sheet. Regards Tom W. ------- Date: Mon, 05 Aug 2002 17:27:43 -0500 From: jrw Subject: Re: Re: A new direction....Myford Change Gears Art: I buy the canvas base phenolite material ( 1-1/2 inch thick plate stock) for some special insulators for my welding torches and it comes from Regal Plastics (located on Wirt, South of Long Point). It would help to sandwich the material between sheets of aluminum if you are concerned about the ends. I use a high speed tool with lots of top angle clearance and a very sharp edge with the shop vacuum hose tied adjacent to the tool bit. Joe Williams ------- Date: Mon, 05 Aug 2002 20:11:20 -0000 From: "volzmechatronic" Subject: Specs & Poetential Sources: Gear Quality Plastic Laminate This is an old c. 1962 spec doc with sources of gear quality plastic laminate known at that time. Norplex is still listed--others may also still be sources. Note the use of "Glyptal" varnish for water proofing -- necessary? http://www2.pratt-whitney.com/procurement/mes_mei/mes3002.htm Art ------- Date: Tue, 06 Aug 2002 17:35:32 -0700 From: Keith Green Subject: Re: Tufnol [Metal_Shapers group] >>> I once had an Myford ML7 and AIR there was some Tufnol in it. Anyway it looked to me like Micarta which is made in the USA. Seems to me that McMaster Carr had a version of it in their catalog. FWIW Larry <<< Try www.redwoodplastics.com or www.Imcplasticsource.com . Sorry that was supposed to be www.lmcplasticsource.com Look for the cotton phenolic laminates. There are hundreds of them but only a few suitable for gears, Micarta and Celeron being two of the trade names for these types. keith ------- Date: Wed, 07 Aug 2002 04:06:13 -0000 From: "volzmechatronic" Subject: Re: Tufnol: Thanx Larry and Keith-- McMaster does have CE and LE grade "Garolite" cotton cloth phenolic resin high pressure laminate sheets. I'll look at them next if Regal Plastics is too pricey on their "Phneolite". McMaster had 1/2 x 12 x 12-inch sheets of CE for $24.87 and LE for $37.72. Redwood Plastics also has sheets of CE grade...anoher alternative source. Art (Houston) ------- Date: Sat, 10 Aug 2002 17:15:35 -0000 From: "tonybakermv" Subject: Making clock gears on the Milling Machines? [original title was "cock gears" which would defeat search engines ;-] Hello all. I have seen a Smith tape showing how to cut gears using the lathe, head stock spindle and vertical milling table. I have the Sherline milling machine, indexing spindle but NO vertical milling table. However when I work out the setup I see I can only make small gears aprox 1in max. I am mounting the cutter on the Z-axis and have the spindle on a block mounted on the end of the X-axis so the indexing plate can hang over the end. The problem is there is only a small movement from center of the Y-axis. Am I missing something! Is there a better way of doing this??? ------- Date: Sat, 10 Aug 2002 11:22:24 -0700 From: "Yasmiin" Subject: RE: Making clock gears on the Milling Machines? Well this is one reason why most gear cutting setups for mills are usually on horizontal mills. However, that being said you should be able to set up the indexing spindle and tailstock? On a plate where the center line of the indexing spindle is off set from the center line of the X axis. The only limit should be the swing of the indexing spindle. I have a fixture like this build on a piece of machined jewelers lathe base using a Levin head stock and tail stock. You can do the same on a tooling plate. Seems like I have seen this setup pictured in something about using the Sherline index head. Yasmiin ------- Date: Sun, 18 Aug 2002 23:18:40 -0000 From: "gjertz" Subject: Re: Gear Mesh: center to center distance calculation In sherline, "builder4wd" wrote: > I have two 64 pitch gears that I want to mesh (one is 100T, the other > 50T). How can I calculate the proper distance between the center of > their two shafts so that they will mesh properly? If I can calculate > the distance, it would be easier for me to correctly position the > holes. Any advice would be appreciated! add the pitch dia together and divide by 2 plus add .001 or more if using Sherline mill. be very shure of your backlash when locating bearing holes. The class of gears is important too. Berg or PIC or other mfgs offer good data in their catalogs. I have very good luck with the Sherling equipment and have done a lot with gears. --------- Date: Mon, 19 Aug 2002 01:48:21 -0000 From: "n2562001" Subject: Re: Gear Mesh: center to center distance calculation As mentioned there can be differences in various gears. For that reason I put a shaft in the lathe chuck and one parallel to it in the tool post. Then put the gears on the shafts and run the cross slide in and out while turning the meshed gears until you have the proper back lash. Then measure the distance between the shafts. Jerry Kieffer ------- Date: Mon, 19 Aug 2002 06:34:12 -0500 From: "Nance, Tom" Subject: RE: Gear Mesh: center to center distance calculation Hi there (name not given), As someone stated before, the distance between centers equals the sum of the pitch diameters divided by 2. I figured you could have reasoned that much out, and what you were really asking is what the heck the pitch diameters were. It turns out that pitch diameter equals the number of teeth divided by the pitch. In your case the pitch diameters are 1.5625 and 0.78125 respectively. So the distance between the axles should be 1.171875. I don't know about you, but I certainly couldn't dial that number into my Sherline mill plus you need a bit of play between the gears, so I would make the centers between 1.173 and 1.175 inches apart depending on how much load they have to carry and how free you wish them to turn. (1.173 for large load, 1.175 for small load - easy turning) Hope this helps. Be sure to check my math before you cut anything; I have been known to press the wrong button on a calculator before. Also, it wouldn't be a bad idea to get a copy of Machinery's Handbook. Barnes and Nobles and Amazon both carry it. It has tons of useful info - like, what's a pitch diameter? Tom Nance ------- Date: Mon, 19 Aug 2002 19:37:40 -0700 From: "Marcus & Eva" Subject: Re: Gear Mesh: center to center distance calculation Hi Builder: The best way I have found, is a bit of a takeoff on Jerry Kiefer's excellent method. What I do, whenever possible, is to put the first gear in position, so it is permanently mounted and will spin freely. Then I mount the second gear on a stub arbor in the mill spindle. I move the second gear into position by moving the table of the mill, and check the backlash by wiggling the meshed gears. When I'm in the right spot, I don't bother measuring anything, I just whip out the gear, whip in the centerdrill and poke in my hole. No measuring, no calculating, and the backlash is exactly as I intended. Cheers Marcus ------- Date: Mon, 7 Oct 2002 19:48:04 -0700 From: "Marcus & Eva" Subject: Re: Gear cutting [sherline] "Dave Hylands" wrote: >David Lehrian on making gear cutters >http://www.redshift.com/~lehrian/BevelGearDocs/Grin dingGearCuttingTools.html >And three different articles on making worm wheels: >http://pw1.netcom.com/~madyn/Metalworking/Gearmaking/Gear%20Making.htm >http://www.tjanstrom.com/hobbingawormwheel.html >http://easyweb.easynet.co.uk/~chrish/worms.htm I had a good look at the websites referred to, for tips on gearcutting and making cutters. I wasn't too impressed with Lehrian's method, and I believe there's a far better way that is easily within the capabilities of any home shop machinist with a Sherline (or any other) mill. What you are trying to create when making a gear profile cutter, is a close approximation of an involute profile which is a specific shape that allows the gear teeth to roll together without rubbing. There is an EXCELLENT reference on this subject by a Brit named Ivan Law. Get his book...it's worth it!!! In it, he describes how the involute profile is generated, and how it can be faked to a degree of precision suitable for most home shop machinist needs. The crux of the job is to get the profile onto a cutter. The shape, according to Mr Law, is so close to a segment of a circle as to make no difference, which means we can get the correct shape by poking a couple of holes of the right size, and at the right locations into a piece of hardenable steel. If we make the holes tapered, we get the relief that we need to make the toolbit cut without rubbing. So we need a tapered cutter whose point diameter is a bit smaller than the finished hole size. The easy way to do this is to make it out of a high speed steel round blank. Set it up in the lathe and turn the taper onto it with a carbide tool. (Yes you can turn hardened high speed steel on a Sherline...I've done it frequently and it works like a charm!) Next, split the tapered end on a bench grinder, as accurately as you can... you're aiming to split it as close to exactly in half as you can get it. Last grind a bit of relief onto the half cone that's left and you have your tapered cutter. Spot and drill your holes undersized in the soft toolsteel gearcutter blank (I recommend O1) and then ream them to size with your new tapered cutter. It's worthwhile to make a pingage to check the hole diameters so you can approach the correct size by incrementally downfeeding and checking with the pingage. After your holes are in, chop away the excess toolsteel with the mill to leave the cutter shape. Harden and draw back, mount it into a simple arbor, and you're in business. At least this way you'll get something that functions as a gear should...the reason Mr Lehrian's efforts failed in service is most likely that the gear teeth were rubbing so badly that they self destructed from galling. Making them out of 4140 as he described in his later efforts is not going to make them work better. Brass will do just fine if the teeth are correctly formed. Cheers Marcus ------- Date: Tue, 08 Oct 2002 04:26:20 +0000 From: SmittysSpeedWorksx~xxattbi.com Subject: RE: Gear cutting Great info, really helps out. I went and ground a HSS just for kicks, and cut slots every 5 deg, just to see the works. Well, it worked just fine, but now I can see that the cutter profile is so very important, that will be the tough part. Now, since I have no knowledge of gear cutting, is it possable make a cutter that will cut both the power side of the tooth, and the coast side of the tooth at the same time. Sorry, that is the only way I know how to describe it! Smitty ------- Date: Mon, 7 Oct 2002 22:30:28 -0700 From: "Marcus & Eva" Subject: Re: Gear cutting Hi Smitty: Gear cutters cut away the spaces between the teeth, and so they will cut one leading flank and one trailing flank of adjacent teeth at the same time. Both profiles must be identical, and are very close to arcs in shape. That is why the "two holes" method of making gear cutters works so well. It's easy to make tapered round holes of exactly the right size, and it's easy to put them in exactly the right spot relative to each other. The rest of the cutter manufacturing simply involves chopping away the excess material from the blank that you put the holes into, and mounting the result onto a shaft (after hardening it of course) so it sticks out the side and works like a little one-toothed circular saw blade. When you slice into the edge of the gear blank with this shaped saw, it cuts out a groove that has the right profile to make the trailing flank of one tooth and the leading flank of the next tooth automatically. Cheers Marcus ------- Date: Mon, 7 Oct 2002 22:52:15 -0700 From: "Marcus & Eva" Subject: Re: Gear cutting Hi Dave: High speed steel round blanks are sold at any tool supply place. They are sometimes called "drill blanks", and sometimes just "HSS rounds" Broken center drills are also a good source, as are broken end mills. For turning, the grade of carbide sold by Sherline works fine, so do the harder cast iron grades and finishing grades. The trick is not to have an interrupted cut, and to take light passes; 0.005" or so seems to work well for me. It's worthwhile to have a diamond wheel to regrind the tips of the carbide tools because they will wear quite rapidly...the only hangup here is that diamond wheels will definitely give you sticker shock. They last forever though...I've got diamond wheels that have been in regular use for over 20 years and are barely worn. To answer your other comments; yes you can make tapered cutters from drill rod or some other oil hardening steel, but they do not stand up as well as HSS. For a "one timer" they'll be perfectly adequate though. It is also possible to get relief by tilting a parallel sided hole, but the profile on the face of the gear cutter will become elliptical instead of round. It's also a lot harder to get the holes in correct relative position because you can no longer just set them by reading on the dials. You now have to pick up scribed lines accurately after tilting the head each way. This means both accurate scribing, and accurate picking up...a fairly tall order if you want to achieve accuracies of the order of +/- 0.0005" or so, which is what you need for reasonable gear cutters. You'll also likely have to single point bore the holes because they will run a bit when they're started on an angled face. A tapered reamer is just so much easier...you can just keep pecking down in small increments until you can barely push your pin gage through. Cheers Marcus ------- Date: Thu, 7 Nov 2002 12:00:57 -0800 From: "Dave Hylands" Subject: Question about clearances I'm planning on building a custom enclosure for a planetary gearbox. The gearbox contains some gears on pins and I basically want to be able to put a piece of metal on each side of the gear (parallel to the flat surfaces of the gear). Off the top of my head, the gears are on the order of 1/8" thick and 1/2" in diameter. How much clearance should I leave between the gear and the plate for grease/oil? The output shaft of the above will run through the mounting case, and I don't think I have room for a bearing (unless they make bearings which are only 4mm (0.157") thick), so I was planning on making a bushing. The shaft material appears to be unhardened steel. What would be a good material to make the bushing out of? This particular application is for a sumo robot, so the motors only run for short bursts (a match can only last 3 minutes), and I don't expect there to be more than a few hours of running time a year (say less than 40). How much clearance should I leave between the shaft and the material? Is bronze appropriate (since it will be kind of like a bearing?) I'm assuming that aluminum will be too soft. Perhaps it doesn't matter for my particular application? I have lots of aluminum, some delrin, some brass and some steel. The guts of the planetary gearbox came out of an 18v cordless drill (in case anybody is wondering). Dave Hylands Vancouver, BC, Canada http://www.davehylands.com/ ------- Date: Thu, 07 Nov 2002 15:46:23 -0600 From: "Bad Brad" Subject: Re: Question about clearances Yes Dave, there are sources for ball bearings in the size that you need. Do a search for Ball Bearings on the web and you will find a bunch to choose from. Some manufacturers actully give load ratings and metal make up of the bearings you need. If you use oil in your transmission you can get bearings that seal, keeping the oil from leaking out. As far as clearance goes a few thousndths using thin thrust washers as spacers. I would tend to think a transmission oil (not automatic) would be better than grease given the use. Grease will not re-apply itself once it has spun off where an enclosed gearbox with the gears partially submerged in oil will always lubricate where it is needed. You definitly want to lube if the gears aren't hardened. Forrest ------- Date: Thu, 7 Nov 2002 20:21:39 -0800 From: "Marcus & Eva" Subject: Re: Question about clearances Hi Dave: The end clearance can be in the 0.005 to 0.010 range without detriment to the function of the gearset. Try to get a hub standing proud of the gear 0.025" or so to limit the hydrodynamic drag of the grease down to the hub diameter. The shaft clearance should be 0.001" or less. Hard grades of aluminum are acceptable as bearing surfaces if they are kept well lubed. 7075 T6 or Alumec 89 are good choices and can eliminate the need for a bushing altogether. Some model aircraft engines are put together this way and run at far higher speeds without seizing up, but they are continuously lubed. Oilite bronze is the best choice if your maintenance will be sporadic. Delrin bushings will work only on a very smoothly polished shaft with zero defects. Any scarring of the shaft at all and the bushings will be chewed to death very quickly. Ditto for Teflon. Hope this helps. Cheers Marcus ------- Date: Sat, 23 Nov 2002 00:43:07 -0000 From: "Thomas E. Jones" Subject: Re: Gear cutters For involute gears, try MSC, here's a web page: http://www.mscdirect.com/PDF.process?pdf=525&Keyword=Y They have very respectable prices, and I don't think you can do better. Clocks historically don't use "involute" gear teeth, but with a special profile. An example is here: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=732520378 These real "horological" gear cutter sets are quite expensive, and you can get one here, from S. LaRose -- a clock-makers'supplier: https://www.slarose.com/store2/store.ihtml?pid=063260&catid=64&step=4 Any good clock-making book can explain the difference between horological gear profiles, and involute profiles. Involute is currently the way most gears are today. I think horological gears don't work well if the smaller gear (pinion) drives a larger gear, it works best if a larger gear drives a smaller. Maybe this is wrong, it's been a while. - tj. ------- Date: Thu, 16 Jan 2003 08:37:00 -0800 From: "Roeper" Subject: Re: How to make a gear ? [atlas_craftsman] > Damon, Try ording Rudy Kouhpt's video on spur gears. > Any copy of Home Shop Machinist mag will have an ad. You know, I'm kinda in the same boat as you are. I'm fixin to make some wooden gears for some wooden clock movements that I want to build (and sell). I started out trying to figure out how I could do it without spending a ton of money but, after 2 years of trying to figure it out, I gave up and bought a lathe, a mill, a lathe/mill combo (the price was very "right") a dividing head and a bunch of other stuff. And it's all "grown up" machinery too, not toy stuff. Now I'm getting everything cleaned up, re-painted, re-calibrated, etc., I'll soon be ready to rock-n-roll (finally). I think the advice of getting one of the "Rudy" tapes is excellent. I bought one of his tapes about operating the Atlas mill right after I bought one for my Uncle. He's been really happy with both. I also bought some excellent books on the subject too. My suggestion is that you spend several hours on the internet getting information for gear makin. There's ton's of stuff there and I wouldn't even think about doing what you are planning without it. There's a lot of things that you are going to need to know about BEFORE you start cutting gears. I know because I'm about halfway through it. I am anxious to get started. I think you're going to want access to a decent horizontal mill and also you're going to need a dividing head with indexing plates and a tailstock too. Involute cutters are expensive so, once you're decided which gear(s) to make, shop eBay for them. They're far and few between but I bought 15 cutters last November for $300. They were all new (never been used). The retail on one gear alone was around $400. the total retail value was over $2,000. I just bought 14 mostlt new cutters on eBay this past weeks for around $78. It's a nice was to make/save some money. My Uncle's mill uses cutters under about 3 1/2" in diameter. My mill uses the bigger ones. I can buy cutters so cheap on eBay that I can give half of em away to my Uncle and still have some really cheap, brand new cutters for my self. I started a little newsgroup about making wooden clocks. All of this info I've talked about here will become posted on the NG in the next several days, I hope. Go ahead and subscribe to the group (heck, it's free) and you can weed out that which does not apply to you. Post message: Wooden_clocksx~xxyahoogroups.com Subscribe: Wooden_clocks-subscribex~xxyahoogroups.com Unsubscribe: Wooden_clocks-unsubscribex~xxyahoogroups.com List owner: Wooden_clocks-ownerx~xxyahoogroups.com Look forward to hearing from you and good luck on the gearmaking. By the way.....I was watching eBay for one of those little Brown & Sharp dividing heads. They sell new for around $1,500 (included 3 dividing plates, tailstock, a few other goodies). They were selling in the $300 to $400 range for used ones. I got sick of wastching them. Then, all of a sudden, this guy comes on who's got a brand new B & S look alike (Asian import) that had a "buy it now" deal for $349.00 so I bought it outright. It's rather nice and I feel I got a really good deal. If you're interested, I can get you the guy's name and such. He's usually got one on eBay and I was pleased with it. Will have images on the newsgroup in the next few days, I hope. Best of luck to ya! Michael Roeper Portland, Oregon ------- Date: Thu, 16 Jan 2003 22:50:26 -0800 From: "Nicholas Carter and Felice Luftschein" Subject: Re: How to make a gear ? I was feeling like I had some extra money and bought a set of 8, 16 pitch import gear cutters from MSC one day. I figured since I had a bunch of Atlas machines, and that they are so common, I would come out ahead in the long run. When I busted a carriage feed gear (I posted about this a while back, it involved an oil can sitting in the wromg place on the lathe bench) I (after cutting a blank gear) set up a dividing head on the horizontal mill, looked up the depth of cut in Machinery's handbook and sooner than you could describe it fully, I had a matching gear. This gear had a 5/16" square hole, so that complicated things somewhat (I borrowed a friends broach), but the long and short of it is that you can make a pretty nice gear quickly if you have a mill, dividing head and the proper gear cutter. the import ones are not expensive, each. http://www.cartertools.com/nfhome.html ------- Date: Mon, 03 Feb 2003 03:15:01 -0000 From: "remlapfluke " Subject: Gearspec program for gear cutting In trying to help a friend make spur gears I found this web page with a free gear calculator. It gives alot of information for the gear cutters out there. You tell it the diametral pitch (12 to 180) and the # of teeth and it gives you all the rest. Looks like there are other interesting programs there too. Jeff http://www.wmberg.com/Tools -------- Date: Thu, 20 Mar 2003 23:17:19 -0000 From: "jeastwoodlm" Subject: Wooden gear cutting: a lesson learned I'm working on a wooden clock (gears and all), the Wooden ClockWorks MLT-5 design (seewww.wooden-clockworks.com/). I just learned the hard way what gear cutting theory had told me about pitch diameter, diametral pitch, number of teeth, and their relationship. This clock uses paper templates that are glued to baltic birch wood and are cut using a scroll saw. There are several gears, the great wheel being 80 teeth and about 7.5" diameter. A scroll saw seemed to me a slow and inaccurate way to cut gear teeth, so I decided to construct an indexing device (one of those projects that has been on the to do list for some time) and use it to index the wheel, cutting with a fly cutter ground to the tooth shape. My indexing device is loosely base on W R Smith's as described in one of his workshop technique books, but I expanded it to allow the use of multiple ganged gears, and division plates. I use a Sherline spindle assembly as the core of this indexer. Construction of that project is another story: in short, I got it set up on the mill, aligned, and the wheel blank chucked in the indexer spindle, ready to start cutting. The gear tooth pattern is printed on the paper template glued to the gear blank, so I aligned the cutter with the outline of the tooth, clamped things down, and cut the first tooth. So far no problem; index to the next tooth, clamp, eyeball it for anything amiss, and cut the next tooth. After cutting 3 teeth I stepped the indexer around 76 more times to confirm that the 80th tooth would come out properly positioned next to the first tooth; looked good! Cut 6 more teeth, and then had to stop, since TheProblem had now became very apparent: the tooth width was not staying constant, rather they were getting narrower with each cut. You experienced gear cutters no doubt know exactly what the problem was, but I had to think about it a bit. Yes, it was the diameter of the wheel blank and my depth of cut. I refer those interested to the various books and descriptions out there on gear cutting; the summary is, the diameter of your blank, number of teeth, and depth of cut must all be in proper proportion, or you won't get a gear with evenly spaced, uniformly shaped teeth. As this clock is designed to work with gears cut with a scroll saw, I think I'll cut them by just lining up each tooth's pattern with the cutter, clamping the work, and cutting, each tooth in succession. This should still be more uniform and accurate than a scroll saw, and I won't have to get the blank to a precise diameter. I'll take a picture or two of my setup for this for those interested. BTW, even though I'm using a Sherline spindle in the indexer, my mill is a slightly larger Prazi 450. This mill was my solution to the "love my Sherline but want something just a littler bigger" problem. Weighing in at 200 lbs, it's still a bench top unit that can be set up by one person (done in three pieces; base, head, and column.) I'm able to use all of my 5400 tooling with it through use of an MT2 to MT1 adaptor. ------- Date: Thu, 20 Mar 2003 23:51:35 -0800 From: Dave Martindale Subject: gear cutting puzzle Ok, I'll show my ignorance and say that I don't understand how you get unevenly spaced teeth. Maybe I don't understand something about your setup. I imagine you have your indexing device with a faceplate or chuck mounted on it, and the gear blank mounted centered on the faceplate/chuck. You cut once, rotate the indexer exactly 1/80 turn, cut again, and so on all the way around the blank. Now, if the shape of your cutter, the diameter of the blank, depth of cut, and number of teeth are not all in harmony with each other, you'll get something that doesn't look like a gear at all, or which has misshapen teeth. But I think whatever teeth you do get must all be the same size and shape and spacing, because every one is formed by a pair of fly cutter cuts using the same cutter, the same depth of cut, and with the same angular distance between cuts. So what am I missing? Dave ------- Date: Fri, 21 Mar 2003 18:15:31 -0000 From: "jeastwoodlm" Subject: Re: gear cutting puzzle Yeah, I had to think about it a fair bit myself before I convinced myself that what I saw was reasonable. The nut of the problem: moving a constant angular distance between cuts does not result in a constant tooth width. If the distance you move each time is not quite long enough, then each tooth gets thinner. I suppose you could consider them still evenly spaced, but it's certainly not the effect you want. ------- Date: Tue, 01 Apr 2003 23:44:09 -0000 From: "Thomas " Subject: Source for gears? I am pondering adding a leadscrew to my Taig, like the one on Tony Jeffree's site. Where is a good source for gears, for the small time hobbyists like ourselves? I've got MSC's catalog, but their gears are a little pricey, and most are too big. What are your thoughts? Thomas ------- Date: Wed, 02 Apr 2003 01:22:38 -0000 From: "J Hamilton" Subject: Re: Source for gears? Thomas, if you do a search on gears here, or go to Walter Anderson's site, you'll find Walter has done the search for gears in the US. I think his were Acytal, of memory serves, and he was building the dividing head. He has a great site set up for his lathe projects. You may hear from him shortly... http://www.geocities.com/wandrson/taig/index.html Good luck, and let us know how it works out! Jim. ------- Date: Wed, 02 Apr 2003 14:46:49 -0000 From: "Walter Anderson" Subject: Re: Source for gears? Thanks for the complement on my site Jim. One item I didn't consider when building the dividing head was to order from the same company Tony used. He suggested it, but I didn't think it would be easy to order from an overseas firm. I would suggest that anyone building one of Tony's projects seriously consider it. I suspect that with global trade the costs might be fairly comparable. It would certainly make the selection process easier. I didn't get an exact match for Tony's gear and had to make some adjustments because of that. If you prefer to purchase domestically here is the company that seemed to have the best match/price. If you can use acetal gears instead of the metal ones Tony used you can reduce the cost by 90%. That said I eventually did use metal gears. http://www.sdp-si.com/ Another possibility is: http://www.wmberg.com/ Though they seem a little less friendly to smaller orders. By the way, please keep us apprised of you progress on the leadscrew. I too am thinking of building this project and would love to hear how it goes for someone else. I love the way Tony has written these projects up. They have the clearest instructions that I have seen. I look forward to his book arriving from Nick! Right now I am contemplating my safety procedures... I nearly took my scalp off trying my hand at metal spinning for the first time this weekend. ------- Date: Thu, 03 Apr 2003 16:11:18 -0000 From: "JohnW" Subject: Re: Source for gears Little Machine Shop sells a full set of change gears for the 7x10 lathes for $29.95 1 each of 30 Tooth gear,35 Tooth gear,40 Tooth gear,45 Tooth gear, 50 Tooth gear, 55 Tooth gear, 57 Tooth gear, 60 Tooth gear, 65 Tooth gear They also sell the gears individually for $5 each except for a 20 tooth for $10. They might be a little big for the taig, I believe they are a metric pitch gear. There is also a design for a gearbox for the 7x10 using these gears in the file section of the Gingery Machine group. John ------- Date: Thu, 03 Apr 2003 18:18:04 -0000 From: "Thomas " Subject: Re: Source for gears Thanks John for the info. I think I might pick these up even if I don't use them for the leadscrew conversion, because I can use them to make graduated dials via Jose Rodriguez's method :) Thomas ------- Date: Mon, 7 Apr 2003 14:15:54 +0200 From: "Pavel Korensky" Subject: How to properly center the workpiece ??? I have one question. I am cutting gears with involute gear cutters and I am using the following setup: The mill head is rotated 90 deg. and the rotary table is clamped to the mill table. I turn the blank in the lathe to the proper outside diameter and drill it. After this, I remove blank together with chuck from the lathe, mount it on the rotary table, center the involute gear cutter over the blank and I start cutting teeth. But it takes a lot of time to properly align the cutter to the exact center of the blank. Does anyone know some trick or fast method how to determine that the cutter is exactly at the center of the blank ? Thx for any tips. Pavel Korensky ------- Date: Mon, 7 Apr 2003 16:30:35 +0200 From: "Pavel Korensky" Subject: And second question about gears I need to make several "combined" gears, basically a combination of larger spur gear (25 teeths) and pinion (10 teeths). I should look like this: | | Pinion | | ======== Gear I think that the best way how to do it is to make the gear, make the pinion, drill the hole in the center of the gear big enough that the pinion will fit in it, and either glue it together with epoxy glue or solder it (the gear and pinion are made from brass). Anyone have some better way to do it? Best regards PavelK ------- Date: Mon, 7 Apr 2003 08:51:21 -0700 From: "Marcus & Eva" Subject: Re: And second question about gears Hi Pavel: The easiest way to center a gear cutter on a gear blank is to do it by eye. The most common, but not the best way, is to put a point in the spindle where the blank will go, and set the center of the tip of the cutter using a magnifying glass. The point is then replaced with the gear blank and the cuts are made. Two errors will occur: 1) the point is not always concentric with the spindle. 2) the center of the cutter has to be estimated. A better way exists: The gear blank is mounted and made concentric. The cutter is mounted and run up and down with the Z axis until it just makes a mark on the edge of the blank. The cutter is positioned, again with a magnifying glass so the top edge of the cutter is in line with the top of the mark. The Z axis is zeroed. the cutter is moved down until the bottom edge of the cutter is in line with the bottom of the mark, and the Z axis reading is noted. The cutter is moved up 1/2 the difference. The mark is machined away when the first tooth space is cut. Your second question about mounting two gears together is easier to answer. Your method will work for light loads only. You need a keyway through both gears if you want to transmit much power. Cheers Marcus ------- Date: Mon, 7 Apr 2003 19:22:31 -0700 From: "Marcus & Eva" Subject: Re: And second question about gears Hi Pavel: Now that I've seen your setup, I can understand how my comments this morning may have been confusing. Let me try again: What I was describing was to make a little mark with the gearcutter, on the surface of the brass before you try to start cutting the first gear tooth. So, with your setup, you'd first lower the cutter, and then move the brass piece toward the spinning cutter using the CROSS feed in tiny steps while cranking the TABLE back and forth with the LONGITUDINAL feed screw.You keep doing this until the spinning cutter nicks a tiny little scallop out of the diameter of the brass. [PARA WAS CORRECTED BY MARCUS] Coating the brass with felt pen first makes it easier to see. If your brass piece is perfectly centered, the edges of the little scallop will perfectly straddle the axis of the turntable. You can then line up these edges with the edges of the cutter (you've stopped the rotation by now), and when you take half of the difference between the width of the scallop and the width of the cutter, you'll be centered on the axis. I like this method because it means I only have to indicate the gear blank in; if you use a point, you have to indicate the point in first, set up your cutter, and then take out the point and indicate in your blank. Another thing you may wish to consider...the setup you've shown is a little bit unsafe. Holding such a thin piece of brass so far from the chuck without any support at the top, means that you risk having the cutter grab at the brass and bending or breaking something. I prefer to set the rotary table up so it's standing up at 90 degrees to how you've shown it, and then to add a tailstock for support. The mill can still be set up as a horizontal, like you have it, but it could be set up as a vertical too. The tailstock keeps the brass from being able to be snatched at by the cutter, and will also keep it in position so the gear will be cut more accurately. If you really prefer the vertical position, it would be a good idea to make a fixture that you can bolt onto the milling machine table that has a little vee shaped cutout at its top end. That way you can at least cradle the tip of the brass and prevent it from bending. The cutter will still be able to snatch at it though, so the tailstock is better. Hope this has been more helpful. Cheers Marcus ------- Date: Mon, 07 Apr 2003 21:59:25 -0700 From: Alan Marconett KM6VV Subject: Re: And second question about gears Hi again Pavel, I'd make a shoulder on the pinion, such that the larger gear's center hole can slip over it. Then Silver Braze (or solder) the two together. Another way would be to press fit the gear on. If you machine and cut the pinion first, then attach the second blank and THEN cut it, you should have good alignment between the two gears. Alan KM6VV P.S. Pretty neat! cutting gears. I've got the rotary table and so forth, but I've yet to get the gear cutters (expensive). What cutters did you find useful, and what are you building? ------- Date: Tue, 8 Apr 2003 14:22:34 +0200 From: "Pavel Korensky" Subject: RE: And second question about gears Marcus, I understand your method now. It is clever :-) I know that my version of setup is a bit unsafe, but it works, because normally, I am cutting bigger gears than the piece which can be shown on my photo (actually, it was a scrap from 10 teeths module 0.5 pinion). The reason why I am using this setup is simple. I do not have the right angle attachment for the rotary table (part 3701). I only have the Tilting Angle table (part 3750). And when I mount the rotary table to the Tilting Angle table and I put it on the left side of the mill, the rotary table handwheel is on the opposite side of the mill. And it is not possible to put the tilting table on the right side of the mill (and tailstock on the left side), because there is not enough room, the tilting angle table/rotary table combo is a big piece. I will change my setup as soon as I will buy the 3701 attachment. Best regards PavelK ------- Date: Tue, 8 Apr 2003 14:55:47 +0200 From: "Pavel Korensky" Subject: RE: And second question about gears Hello Alan, I bought the gear cutters approx. two years ago. I bought two sets (each set has 8 cutters), one for Module 0,5 and second one for Module 1. Mainly I used them for repair of R/C servo gears and also for making some parts for my robotic hobby. Now, I am trying to do the first "serious" work with them - small gearbox for a DC motor. You can see the the rough (not yet completed)design of the gearbox at http://groups.yahoo.com/group/sherline/files/gearbox1.jpg I am trying to make the design and manufacturing process as simple as possible. The gearbox uses only one type of pinion and one type of spur gear. I am making the spur gears (except the last one, which has a different diameter of the center hole) all at once with the following process: In the lathe, I turn the blank between the 3-jaw chuck and live center to proper outer diameter. Than, I make a groove in it with my parting tool (the depth of groove is something like 2 mm or similar, just deeper than the total depth of cuts for teeth) and grooves are spaced exactly 3 mm (the thickness of spur gear). When grooves are finished, I remove the live center and I center-drill, drill and ream the blank. After this, I remove the chuck with blank from lathe, mount it on the mill, align the work and I cut the teeth. When the teeth are finished, I put the chuck with blank back onto the lathe and I finish the parting. And I have couple of spur gears. :-) The operation for making pinions is similar, except that there is no parting. I simply make something similar to pinion wire and than, I am using my small Proxxon (something like Dremel) with small grinding wheel to cut the pinions to specific length. Best regards PavelK ------- Date: Tue, 8 Apr 2003 08:15:15 -0700 From: "Marcus & Eva" Subject: Re: And second question about gears - exact URL of the pictures Hi Alan: I've used this method extensively, but only for rough setting up, when I don't need super precision. With care, you can get within 0.002" TIR consistently, but closer than that is hit or miss in my experience. The problem is that the chuck is usually not closer than 0.002 TIR with respect to the turntable axis, especially if it is mounted like the Sherline 3 jaw, and not adjustable for position on the turntable platter. Whenever the job must be very accurate, there's no substitute for dialling the job in concentrically with the rotary table. Whenever I can, I use the 4 jaw chuck mounted to the turntable, because it allows easy fine tuning of the concentricity of the part relative to the rotary table. I ALWAYS turn the turntable and measure the actual runout of the part, correcting it as necessary to get the tolerance I can live with. Finding the position of the mill spindle is then as easy as indicating the part with the indicator clamped in the mill spindle. Lots of guys clock in the center bore of the turntable with the spindle and then clock in the part, again with the spindle. They're almost always off by much more than they were aware of, because of tolerance build-up. To go back to the cutting of gears...this is a situation where precision of the order of 0.0005" TIR is necessary to get decent performance of the gears. (lower tolerance gears can certainly be cut, but they won't perform well at speed or under load.) That level of precision really requires clocking the gear blank in to be concentric with the turntable, by actually rotating the turntable and adjusting the position of the blank to get as close to zero runout as can be achieved. Hope that helps. Cheers Marcus ------- Date: Tue, 8 Apr 2003 11:55:08 EDT From: tmwade4x~xxaol.com Subject: RE: And second question about gears I have a rotary table, which I bought used, but haven't actually used it yet. But I don't have the right angle attachment, which is a little bit pricey. However, I have been needing to hold large chunks of cast iron, which I then mill into a cube, more or less. The interim solution, which works pretty well, is to mount the cast iron block to a cast iron "angle block". I bought a slotted, 2" x 3" or so block, but will replace it soon with one which is not slotted. The slots are in the wrong place, and are too big for the Sherline's # 10 screws. For about the same money I will buy next, a 2" x 2" angle block, which is NOT slotted, and drill my own holes. I've also thought perhaps that one of these blocks could be drilled to make a right angle holder for the rotary table. Best thing is that these blocks are now in the sale catalogue for MSC and Enco for less than $10 each, in the smaller sizes. Tom Wade Hope, Indiana ------- Date: Tue, 08 Apr 2003 12:49:58 -0700 From: Alan Marconett KM6VV Subject: Re: And second question about gears Hi Pavel, thanks for posting the JPG! A SERIOUS design! Well, I know very little about gear cutting, so I don't know what Module 0.5 is! I know I might want a 14.5 degree pressure angle, and MSC comes up with cutters 1-8 for a 2.5" (63.5mm) size. A sample: HSS 141/2° Involute Gear Cutters Diametrical Pitch: 14 Cutter Diameter: 2-1/2 Pressure Angle: 14-1/2 Industry Number of The Cutter: 1 Material: HSS OK, that sounds big. How big (dia) and hole size are your cutters? I too am in a quandary on how to get the adjustable angle table, rotary table, chuck and a tailstock all on the table of my 5400. I believe the right angle table helps, but I want it adjustable! To further complicate matters, I have the CNC rotary table, which has a big motor hanging out! Best regards, Alan Marconett KM6VV ------- Date: Tue, 8 Apr 2003 22:18:38 +0200 From: Pavel Kořenský Subject: RE: And second question about gears The main problem is, that I really do not know the way how you in the USA calculate the gears. I tried to read the chapter about US gears in Machinery's Handbook (25th edition), but it is too complex for me. Here in Europe, we have so-called Module system for gears, with several simple calculations. Basically, the "module" of the gear is equal to the pitch diameter divided by the number of teeth, whereas diametral pitch is equal to the number of teeth divided by the pitch diameter. Outside diameter of the blank = add 2 to the number of teeth and multiply sum by the module For example gear has 25 teeth and module 0.5 - outside diameter is (25 + 2)/0.5 = 13.5 mm Working depth of gear = 2 x module Depth of cut = 2.157 x module (dunno why, but I can accept it :-) My gear cutters also numbered 1-8, but according to Machinery's Handbook, the numbering is reversed when compared to USA. We use Nr. 1 for smallest number of teeth and Nr. 8 for 150 teeth and racks. There is one set of 8 cutters for each module. Diameter of my cutters is 40mm for Module 0.5 and 50mm Module 1. I do not know how big are the cutters for Modules 2,3,4,5... because I never saw them. They all have a hole 16mm dia., I made a special arbor for them. Actually, this arbor was my first Sherline project (beside trying to reduce diameter of some scrap aluminium on lathe) and I tried it 6x before I learned how to properly turn a Morse taper with my cross-slide attachment, drill the hole etc. and have everything concentric :-) Best regards PavelK ------- Date: Tue, 08 Apr 2003 13:51:48 -0700 From: Alan Marconett KM6VV Subject: Re: And second question about gears - exact URL of the pictures Hi Marcus, Thanks for the comments. I can see how the additional step of using a 4-jaw independent chuck, clocking in the part to the rotary table, and THEN clocking in the part to the spindle would be an improvement, and the only way to go for maximum reduction of TIR. I'll definitely do that for gears! So far, my requirements have not been that tough. How about your thoughts on which gear cutters to buy? I'd like to limit it to just a few, to start (expensive)! I have a few odds and ends of brass Boston gears, and I'd like to make mates for them. something in the 20 Diameter pitch range? That would give me 20 teeth on a 1" dia gear (14.5 angle)? MSC has them priced individually, so unless I find a set. 7/8" or 1" diameter holes in the cutters would be needed. I have bought the 3217 gear tooth cutter holder; now if I can only grind a cutter! I'm thinking of using a small Dremel grinding wheel in the spindle, and using the lathe to grind the cutter (ways covered). At least I'd have some control. Mill could also probably be used. The adjustable angle table might also be of use! Best regards, Alan KM6VV ------- Date: Tue, 8 Apr 2003 20:39:39 EDT From: catboat15x~xxaol.com Subject: Re: And second question about gears 4/8/2003, pavel.korenskyx~xxdator3.cz writes: > Here in Europe, we have so-called Module system for gears, with several > simple calculations Our US system is just the inverse of your module system. Pitch diam = number of teeth/diameter. Your module system is just the opposite where Module = diameter/number of teeth. Of course you have to measure things either in those funny units of the length of your thumb, or some fraction of the distance from the north pole to Paris or whatever. If you find the old imperial system confusing, your forebearers became one of the world's leading techinical societies by making change in a money system where 20 shillings made a pound and 21 shillings made a guinia or something like that. While we on this side keep our minds agile by having most scales marked in 16th, 32nd and 64th while our mikes measure in 1/1000. Have you seen the lathes and mills from China where they use 16 TPI on lead screws and mark the dials in 1/1000 with just a bit left over? (Just kidding, of course) John LBSC Virginia LBSC Tich 200 some feet of 3.5 inch ground level track ------- Date: Tue, 08 Apr 2003 17:44:31 -0700 From: Keith Green Subject: Re: And second question about gears The gear cutters you're using are called "single-cutters" (least here in North America). The diameter will change with module/DP. As the teeth get bigger the diameter will increase. The diameter will not change with the cutter number. Each cutter will do a different range of numbers-of-teeth but the drawback is that, to do this, the profile of the cutter can only be an approximation of the correct tooth profile. The first in the series has the greatest involute curve and will only do a couple different numbers-of-teeth. The last has a profile with no involute curve and so will cut rack teeth. In our shop we have 1 dp cutters; some bigger, but these get into "circular pitch" designations. These cutters are only used for low tolerance applications due to the problems of centering the cutter and the fact that, as you cut the workpiece, it will tend to "grow" imperceptibly with each cut (much like a piece of slightly green wood). Not a problem for the little guys, though, and about the cheapest way to go. If you have a gear 60" in diameter and try to cut it all the way around, each tooth in succession, the last one will tend to be out of pitch with the first. The older guys tell a story of a Frankenstien machine they once built up out of two or three scrap ones that would single-cut a 20-foot or so diameter gear. It did this by cutting one tooth, indexing around say 60 degrees at a time until it came back to the start, whereupon it would index one pitch and go around again at 60 deg. increments, thereby averaging out the error. These were gears for swing bridges and stuff like that; really rough service. We have one now to do this, but a little smaller. Last gear we cut on it cut for 2 months straight, 2 shifts a day. 2 or 3 roughing cuts and one finish. As to the 14.5 degree and 20 degree designations, the 14.5 is the older of the two. The current standard is the 20 degree, adopted due to it's greater strength. You'll find 14.5 degree on a lot of old equipment and, of course, all Acme threads. The metric form of the Acme is the 30 degree trapezoidal. The metric one is mathematically simpler to generate and has a stronger tooth. Sorry for the ramble, hope it interested somebody. keith. ------- Date: Tue, 8 Apr 2003 20:30:31 -0700 From: "Marcus & Eva" Subject: Re: And second question about gears - exact URL of the pictures Hi Alan: Gear cutters are awfully expensive for the amount of use they get in most shops. You need 8 cutters for each module (or DP) that you want to cut, so you can end up spending a fortune. You also need different cutters for teeth of different pressure angles; 14.5 and 20 degree are the most common but oddballs do exist, and it's difficult to tell what you've got just by looking at it. So gearcutting is a pricey proposition if you use proprietary cutters. Making your own cutters is possible; Ivan Law has a book out that describes how to fake the involute profile with a radius,which, of course, makes it possible to bore the shape in the mill using a piece of O1 as the toolblank and flame hardening it afterward. I prefer to grind the profile using a dressed grinding wheel, but then I have a surface grinder and a radius dresser. I've often thought of offering HSS single tooth gearcutters on the market, making them in batches of 50 or so at a time and selling them on the net. Perhaps this is the time to start? Cheers Marcus ------- Date: Wed, 9 Apr 2003 09:51:43 -0700 (PDT) From: alanx~xxsfu.ca Subject: Re: Gear cutting Marcus; Sounds good to me ! I've got this cool little HMill that I bought about 5 years ago with the intention of making my own gears. To date, I've yet to cut a single one, being largely put off by the cost of the cutters, even on eBay. I then got it into my head to make my own cutters, based upon the design at http://www.metalwebnews.com/howto/gear/gear and even recalculated the table a bit for more exact fits for any particular number of teeth, as opposed to the approximated fit of any given "1-8" cutter. But, lacking a means of hardening the interim forming tool, that's as far as I went. So, if you do feel so enthusiastic as to make affordably priced cutters, count me in. Alan ------- Date: Wed, 09 Apr 2003 10:55:51 -0700 From: Alan Marconett KM6VV Subject: Re: And second question about gears Hi Marcus, Yes, I think it's a good idea to make available sets of ground tool blanks! I was thinking about bothering someone to make me a blank last night! "piece of O1" ? How would you "bore the shape in the mill"?? I know, buy the book. Either that, or perhaps you'd be kind enough to work up a procedure for us amateurs to make them on our equipment. Maybe a tiny Dremel type grinding wheel could be used in a mill to grind the cutter profile. And the angle table could be used to get the relief's right. I'm not even sure which pressure angle OR DP I'd want! I'd love to find a loose cutter, somewhere in the mid range of teeth, and just try cutting some gears! Best regards, Alan KM6VV ------- Date: Wed, 9 Apr 2003 21:03:50 -0700 From: "Marcus & Eva" Subject: Re: And second question about gears Hi Alan: Basically the involute profile can be faked with a radius...it's done by constructing an arc whose center is defined from the intersection of a line drawn from the center of the gear at the pressure angle that you've chosen (from the vertical), and the base circle of the gear. The radius of the arc is determined by the intersection of a vertical line from the center of the gear and the pitch diameter. These arcs are of the order of 1/4" radius for a 20 DP gear with 40 teeth. They get smaller as the number of teeth diminish, and approach infinity as you approach a rack. So, you determine the size of the arc you need, the distance between the arcs that defines a tooth space, and the distance in from the tip of the tool to the centers of the two radii that you need to get the correct tip width and the right flank shapes. Now you can bore a pair of holes in a piece of toolsteel (O1 is a general purpose oil hardening toolsteel that flame hardens very well and is easy to get.) You make them at the correct spacing (on the mill, so you can just dial in the distance with the table feed) and to the right size (using the boring head) , then just nip away the excess at the tip end, and you've got your basic profile. If you want to put the relief on right away, you can taper the two bores so they're the correct diameter at the small end. A tapered "D" bit is the usual way to do that. Now all of this is a fair PITA, but there is a far better way that's doubly nice if you've got CNC (even more so if you've got 4 axis CNC) This method is analogous to the old Sunderland gear generating process, which uses a shaper that has a bit of a rack of the correct pitch and pressure angle, acting as the cutter. The rack reciprocates back and forth across the face of the gear blank on its cutting stroke and the gear rotates a tiny bit after each cutting stroke, so the rack also moves a tiny bit end to end, in order to stay in mesh with the developing gear. This motion can be easily duplicated with a rack shaped rotating cutter of the correct pitch and pressure angle, and a CNC turntable on which the gear blank is mounted. There are two HUGE advantages to this method: 1) It is a true gear generating method, so the involutes that are produced are correct for each tooth count and are not "faked" in any way. 2) only ONE cutter is needed to produce gears of any number of teeth of a given DP (or Module for those of us who think metric) This is how I cut all my gears now...it's fast and very accurate. What I still do, is to run them by hand on the Bridgeport because I haven't had time yet to get my Sherline rotary table to talk properly to my Defiance CNC, but here's the future plan: I will finish writing the subroutine that generates the correct G code to co-ordinate everything and get the whole method up on my website as soon as the site is running (my web guy tells me next week or so) and the subroutine is intelligible to others and works without problems. I'm trying to get it linked from an EXCEL table, so you just have to input the DP & how many teeth you want, and the subroutine does the rest. I will also start making cutters of popular DP's...Sherline threading gear DP (I think it's 24 DP but I'm not sure right now) is likely where I'll start. When you know what DP gears you want, I'll run some cutters through the surface grinder in that pitch, and you can buy one of them off me together with a copy of the subroutine. (assuming you're a CNC driver...if not, I will substitute the EXCEL spreadsheet and the instructions) I'm aiming for a pretty reasonable price point for the pair, and remember...you only need ONE cutter to cut gears of ANY number of teeth that you care to in that DP and that pressure angle, and they'll all have EXACTLY the right involute profile. I still need to see how many I can gang up on the grinder, and what price I can get the HSS for in production quantities, before I commit to a firm price. The "how to make it work" part will be on the website so people can refer to it. This is all going to take a bit of time, but I've been wanting to get this moving for a long while now, so bear with me, and I'll make it happen. Cheers Marcus ------- Date: Tue, 15 Apr 2003 15:53:06 -0000 From: "paul_probus" Subject: Re: Replacing Zamak parts with Steel > Has anyone done any research into replacing the Zamak (pot metal) > gears that the Atlas mill uses with steel gears? > I am rebuilding an Atlas mill and while I am fortunate having a gear > train in good shape, I understand that these gears do degrade with age. > Any information would be appreciated. I will offer another alternative. Cast the gears using ZA-12. ZA is similar to Zamak in that it is a Zinc-Aluminum alloy, however, it is not supposed to be as prone to corrosion as Zamak is. From what I understand about ZA-12, you can cast the gear without having to cut the gear teeth using the original gears as the patterns. You can give it a shot, ZA-12 melts at a lower temp. than aluminum and you can make the alloy by mixing scrap zinc parts (such as EMT fittings) with aluminum and get an alloy that is very close to ZA-12. See the hobbicast group for more info. on ZA-12. Also try the metalcasting group, although it is not as active as hobbicast used to be. For more detailed info. on the alloy itself, try Eastern Alloys' web site. They have a lot of useful info. there. Paul ------- Date: Tue, 15 Apr 2003 11:06:16 -0500 From: Jon Elson Subject: Re: Re: Replacing Zamak parts with Steel >can make the alloy by mixing scrap zinc parts (such as EMT fittings) >with aluminum and get an alloy that is very close to ZA-12. I have serious doubts about this last part. Zamak is a good material for making bearings and gears. it has good self-lubricating properties, is strong and wears well against itself. I can't believe, from my experience with such, that you could get scrap zinc such as EMT fittings to survive more than a day if recast as Atlas gears. The Zamak gears, etc. are not prone to corrosion if actually IN the lathe, and covered in lube. (If left out, and dry of oils, then corrosion could be a problem after some time.) And, if you are talking about replicating the parts from the original gears by sand casting, the replicas will have a rough surface finish that will have to be cleaned up in the bore, keyways and tooth pattern. This might not be a big deal, however. There will also be a size error due to shrinkage after the casting has cooled. Jon ------- Date: Tue, 15 Apr 2003 20:00:56 -0700 From: "Dan Hill" Subject: Re: Re: Replacing Zamak parts with Steel I have been busy with other projects lately and once again have not been spending as much time as I would like on my mill rebuild project and have only been sporadically watching this thread, but I have been working on the tooling to produce the gears for the feed box and had a thought that I wanted to pass along. The three gears inside the feed box are steel (on my mill anyway) but the gear that connects it to the rest of the gear train is zamak. Now I agree that it was probably cheaper to reproduce it that way but I would suggest that it was probably also engineered that way because if something became jammed up with chips, dried grease, etc. it is a whole lot cheaper to replace a zamak gear than a zamak gear case which now is non existent. In the near future I will have replacement gear housings as well as the gears, but the zamak gear will still be a whole lot cheaper than the housing. I would suggest that we be sure of what effects our "improvements" actually have before we do more harm than good. Just a thought, Dan. ------- Date: Wed, 16 Apr 2003 11:04:53 -0700 From: "Bob May" Subject: Re: Re: Replacing Zamak parts with Steel Actually, the gears will give way before damage to some more important parts of the lathe will. Considering the actual power needed, I'd probably try using plastic gears and make a standard center for them and apply that as a clamp to the plastic webs. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- Date: Wed, 16 Apr 2003 15:51:47 -0400 From: "Rigrac" Subject: Re: Re: Replacing Zamak parts with Steel We at work will sometimes use a gear made out of Micarta (a synthetic wood-like product used a lot in electrical motors as it is non conductive ) especially to drive lead screw or feed shafts on lathes. It will shear teeth off gear in case of a crash etc. Some people also call this material Bakelite. Ron ------- Date: Wed, 16 Apr 2003 15:32:54 -0500 From: "Rodent" Subject: Re: Re: Replacing Zamak parts with Steel Lots of pumps and stuff use a micarta strip as the interface between two shafts so if the pump seizes the strip breaks and not something more expensive. ------- Date: Thu, 17 Apr 2003 16:17:07 -0000 From: "paul_probus" Subject: Re: Replacing Zamak parts with Steel Jon, You need to expand your universe a bit. Please read through the ZA- 12 material on Hobbicast and makeup your own mind on ZA-12. Perhaps I was not clear enough in my previous message, I was not referring to making gears out of scrap EMT fittings, I agree that that would not work well. Instead, I was saying that it could be a good cheap source of Zinc to be mixed with Ally to get an alloy very close to ZA-12. It has been proven and there is a recipe on Hobbicast for doing it, it is based on the density of the source Zinc alloy that you use (such as EMT fittings) and approx. how much Ally weight is needed based on using Ally wire and/or soda cans since both are fairly close to being pure Ally, compared to other alloys that are commonly available. Also, I only used EMT fittings as that was the first thing that came to me, old small engine carbuerators (sp?) and other sources of scrap zinc alloys can be used in the making of homemade ZA-12. In addition, to being used as bearings, at which they are supposed to accel. at, as you mentioned, ZA-12 is also, strengthwise, equivalent to class 40 cast iron. Not too shabby for an alloy that melts at, if I remember correctly, < 800 degrees F. As far as shrinkage, I am not sure about how much shrinkage you would get. I do remember the Eastern Alloys site mentioning that shrinkage is small enough that it could be used to make near to 1:1 replicas, but that may be under more tightly controlled die casting methods that a home shop would not be able to hold to the same tolerance. In either case, a ZA-12 gear blank would then be advisable. And as far as a rough surface, again, look at the photos and files in Hobbicast, there are some pretty impressive details that can be replicated with oil based fine grained sand that you can't do with normal water based green sand. I'm not saying that the surface would be as smooth as a machined surface, but depending on how fine the sand was, you could get it good enough where the surface could be used as-is. As far as the corrosion of the Zamak gears, from what I understand, and bear with me I'm not a metallurgist, Zamak alloys suffer from a problem with what is called "intergranular" corrosion due to the dissimlar metals that make up the alloy. Again, I believe that this goes on even when the gears are in the lathe and covered with grease, although perhaps not as fast as when the gears are left out with dried on grease or no grease. As I said, read Hobbicast and then you can draw your own conclusions about using ZA-12. Everything that I have seen on it leads me to believe that it is underutilized for home metalcasters for projects. Though in no way do I mean to imply that it can be used for everything. Ally, Brass and cast iron alloys have many places where they are much better choices. Unfortunately, I believe the home metalcasters think of failed and/or corroded Zamak whenever the thought of using ZA crosses their minds. Paul ------- Date: Thu, 17 Apr 2003 12:30:19 -0500 From: Jon Elson Subject: Re: Re: Replacing Zamak parts with Steel It just sounded pretty tricky to me to mix various scrap metals together blindly (ie. without chemical tests to figure out what the composition is) and get anything that works well. But, maybe you really can do that - just weight things out before melting them together. Well, I used to have a 1941-vintage Atlas 10" lathe, and I still have the change gears that came with it. they are oily, and show NO corrosion whatsoever. I had those gears in the lathe when I crashed the carriage into the tailstock under power feed, and the "harp" that holds the gears (cast iron) and the reversing gearbox (Zamak) were destroyed completely. The gears didn't even get a chipped tooth. If those gears were not damaged after over 50 years of storage in damp plants and basements, they are not corroding very fast, for sure. I think if you buried them in the back yard, they'd disappear in less than a year, though. Jon ------- Date: Thu, 17 Apr 2003 12:46:20 -0500 (CDT) From: dswrx~xxwebtv.net Subject: Re: Re: Replacing Zamak parts with Steel According to the Atlas Manual of Lathe Operations, (circa 1955) the Zamak Gears and other parts of these lathes were made by high pressure casting machines. This most likely is the reason for the high quality of these parts. As far as the "corrosion" of Zamak, this is a function of having impurities in the alloy. If there are impurities, the Zamak will craze and fail in a few years of manufacture. If they have survived 50 years, I would think they have past the "impurity" test! Leo (pearland, tx) ------- Date: Mon, 22 Sep 2003 00:06:01 -0000 From: "n2562001" Subject: Re: watch makers gear cutters? [sherline] >> I have been looking for some 0.25mm module bevel gears and below >> 2.6 to 6 mm dia If you have any tips or links on cuting them let me know >> this is New to me. >> I have a cnc set up and lathe and the sherline motion controler >> for my rotary table.also I want to make molds of these gears >> but I cant figure out how you cut a gear mold this size...Any one >> know what tool is used? I have micro end mills but even these dont work.. >> Thanks john > John. Cutters of .18 module and up are available from Frie&Borel at > 800-772-3965. They run about $90.00 each. Cutters under .18 module > are very hard to find and very expensive. Also you rarely find the > size`s you need. For that reason I machine and harden single point > cutters for most of my small gear cutting. > Jerry Kieffer > > Any one have any links to very small gear cutters.. Ivan Sorry for not responding but I have been out of town for a few days. For the most part bevel gears can be cut with standard gear cutters if you utilize the proper angles. If you are new to gear cutting the procedures are covered in most machinist hand books. If it is not clear just go ahead and cut a gear anyway and it will all fall into place. Jerry Kieffer ------- Date: Mon, 22 Sep 2003 00:47:14 -0000 From: "n2562001" Subject: Re: watch makers gear cutters? Bob: The reason I machine the cutter is that it can be cut more uniform and accurately than grinding free hand. ( At least if I am doing it ) I use Brand name oil hard or air hard drill rod and harden per manufactures printed instructions on the packaging. I have not found the need to temper the cutters. When reproducing a clock gear I copy the tooth form on the sample gear. For the most part the teeth are straight tooth and you only need to measure the bottom tooth space and the radius at the top of the tooth. You will find that almost all of these radiuses will be very very close to standard size end mills. Once the end mill is selected it is used to machine both sides of the cutter to proper width and will form the proper radius for the top of the tooth. Hope this helps. Jerry Kieffer ------- Date: Mon, 22 Sep 2003 12:12:07 EDT From: wanlikerx~xxaol.com Subject: watch makers gear cutters You will find some clock gear cutters in the Timesavers catalog on page 120, at $40 each: www.timesavers.com You can buy or download their catalog as a PDF, or just view it for free. Get the Gears and Gear Cutting book by Ivan Law, available thru: wiseowlx~xxsprintmail.com That book will show you how to make the gear cutters like TimeSavers has. I did not look to see if all the clock gear cutters dimensions were in that book or not. Make a simple jig, and cut and harden the cutters. Also there is a simple method of using a holder to make single point cutters, and then move a spacer, and use the same holder to cut the gears. The holder jig, is like the Sherline Gear cutting cutter holder, #3217, in fact with 3/16 bits, you can use that method to make and use the single point cutters using the #3217. Using this method, you can make the cutters on your lathe or mill. bill ------- Date: Mon, 22 Sep 2003 13:03:31 -0500 From: "Al Lenz" Subject: RE: watch makers gear cutters Bill and list, I would like to compare Ivan Law's method for making a single point gear cutter with Jerry Kieffer's. For those that don't have the Ivan Law book, he makes a form tool using two disks or 'buttons' mounted on a shank. The diameter of the buttons is determined by calculation, (he provides a diagram) or from a table which he also provides. This form tool is then used to cut the single point cutter. As Bill described, the blank is mounted in a modified holder offset by a shim (in order to get the rake). Now Jerry's and Ivan's method have more in common than would appear on the surface. Both use a round cutter to approximate the theoretical correct tooth form. But rather than making a pair of disks for a form cutter, Jerry selects an end mill of the same (or closest) diameter. Then mounts the blank in the mill vise at a slight angle to provide the rake. Three cuts and he is done. His cutter is virtually identical to the one made by the Ivan Law method. Except that he can (and DID at a 2002 NAMES Seminar) do the whole thing including hardening in TEN minutes. He described this process a few posts back, but I wonder how many really picked up on the true significance of this brilliant yet simple method? It is an improvement by several orders of magnitude over the old way, IMO. Al Lenz ------- Date: Mon, 22 Sep 2003 20:22:11 +0100 From: "Mark Howard" Subject: RE: watch makers gear cutters Al, I've not tried Jerry Kieffer's method, but I have used Ivan Law's method and can confirm that it is time consuming and a serious pain in the nether regions! Thanks for sharing the end-mill method it sounds incredibly quick and simple. I guess that the limitations may be in getting the right sized end-mills - especially when making replacement gears when you can't design the tooth form with available tooling in mind. It would be worth working out how much latitude there is in the radius of the tooth tip. The profile formed by a circular cutter is a workable compromise on the involute curve ideally required, I wonder how much compromise could be made on the ideal radius as well. When I get some time, I'll do the calcs. (unless someone's already done them?). BTW I have identified a number of errors in the tables contained in the Ivan Law book. They're quite easy to spot if you draw up a profile of the cutter from the table data before you commit to cutting steel. Regards Mark Howard ------- Date: Mon, 22 Sep 2003 13:05:57 -0700 From: "Marcus" Subject: Re: watch makers gear cutters Hi All: There is a better way even than that described by Jerry Kieffer, and that is to use a tapered cutter to generate the shape. That allows you to get the diameter spot on, and permits also, if desired the CNC profiling of the whole tooth shape from a true involute curve generated in CAD. The cutters needed are not difficult to make or buy, and can be used for many different sizes of gear cutter. They also simplify the setup to get proper relief angles on the blank. If the taper cutter is carbide, it can even be used on a hardened blank to either recut it to a different shape or to sharpen the original shape by recutting it. There was a fairly extensive thread about this a couple of months or so ago. Cheers Marcus ------- Date: Wed, 01 Oct 2003 09:40:31 -0500 From: jrw Subject: Re: GEAR CUTTING MACHINE Doug: It is easy to cut the the worm gear. Rough out the teeth and then change the cutter to a worm hob and feed the gear blank into the cutter while the gear to be machined is allowed to 'free wheel'. You can make worm wheels on your lathe by using a tap for the hob cutter. Joe W ------- Date: Sat, 04 Oct 2003 10:42:43 -0000 From: "Art Volz" Subject: Gear Cutting Machinery: c. 1890 FYI-- Interesting chapter on gear cutting and gear cutting machinery from Joshua Rose's "Modern Machine Shop, Vol 2", 1887-88. http://digital.lib.msu.edu/applied/modernmachine2/ASBch24.pdf Art ------- NOTE TO FILE: The following gear topic diverges from various subjects July-October 2003 in the Metal_Shapers group containing info on how we might make a replacement gear for the Phenolic bull gear used in an AMMCO shaper; those are reported in the AMMCO Shaper text file and may be useful to others faced with making special gears or working with Phenolic materials (resin-cloth laminates available under many names). ------- Date: Sun, 12 Oct 2003 16:50:51 -0500 From: Mike M Fendley Subject: New gears for the Dvorak/Lewis > All that having been said, "Hey Mississippi Mike, do you need any > help in machining an Al 6061 bull gear for that Dvorak/Lewis > shaper...made the Russki way? (Wonder if the Russkies used any > aluminum gears in their T-34s? I don't think so, but mainly becuz > in > WWII, the big one, they needed all the aluminum they could get their > bear claws on to build airplanes with.) Art (Houston. Art (an all you shaper nuts listening in), With Art's drawings and info on the Lewis gears we decided to make the Lewis bull and pinion gears out of steel. Got the 8DP #2 gear cutter off the bay for $10. Needs sharpening. Had a former kid in the machine shop class come over just today, said he'd take it back to the robotics school he's going to and they'ed professionally sharpen it for nuthin! (Just gotta find that 8DP #7 for making the pinion now!) Another friend has put me onto a place here locally in the Quad Cities that might have an inch thick "slab-o-steel" that I can turn down to 10" diameter to get the 78 tooth Lewis gear. So far so good on the Dvorak/Lewis project. The high school kids finally finished making the 4 gears we needed in one of our lathes (that was wrecked last year by a student unitentionally. Lathe no longer made, no way of getting parts.) One 16/32 sliding duplex gear was made from scratch with a keyway - perfect! One other 16/32 duplex just had it's bigger gear chewed up. Turned it down some and pressed on a steel ring then added 3 set screws at the joint line and cut it. Again a winner. Finally we had to make just one single gear of 32T and put the whole thing back together again. Hopefully, by the end of the week the kids will have 3 lathes to use instead of two. They are excited! I am certainly no gear expert, just a rank amateur habby machinist. But they are sure fun to make and it's a joy to see a machine using them! If we could find a big plate of cast iron for the Lewis bull gear, I'd rather go that route, but I'm at a loss as to even begin to find something like that (unless it's a bigger gear we could just cut down . . . . hmmmmm) Mike in the gray-bus in Iowa just a ponderin Lewis gears . . . . ------- Date: Mon, 13 Oct 2003 05:44:56 -0000 From: "dreilanderecht" Subject: Sharpening gear cutters and other thoughts While I too would not want to cause the premature demise of my gear cutters by using them on some unsuitable material, I'd also say that sharpening them need not be too big a deal. They are designed so that all you need to do is remove the same amount from each face at the same angle and they will still produce the correct form. This will require indexing equipment and a small grinding wheel, but presumably if you are cutting gears you at least have the indexing equipment. It would be important to keep the rake angle (if any) the same since changing it would change the form cut slightly. As for blanks, it seems to me that you have the choice of getting a slice cut off a round bar, which makes it possible to get cast iron, steel, or aluminium up to quite big sizes. Another approach would be to get a circle cut from sheet, many suppliers will do this...used to be flame cut normally, but I suppose you might get it done other ways now. You are not so likely to get such a wide range of choices of material that way. I'd hate to have to do one for my big Alba, the gear on that must be about 18 inches in diameter. I don't have a lathe that big! regards John ------- Date: Mon, 13 Oct 2003 09:36:55 -0500 From: jrw Subject: Re: Sharpening gear cutters and other thoughts John. Use your rotary table in the mill to cut large diameter circles. Bolt the material to the table and start cutting. Joe W ------- Date: Tue, 14 Oct 2003 09:47:38 -0000 From: "dreilanderecht" Subject: Re: Sharpening gear cutters and other thoughts The minor difficulty here is that I don't in fact have a rotary table of any size, just a baby one I made for the Unimat. But actually what I was referring to is that for bull gear blanks it might be just as easy to acquire them roughly to size, either as a slice off a bar or as a circle cut from flat. I've made a blank for an Ammco gear by cutting a slice off a cast iron bar with the bandsaw. This is about as big as that bandsaw will manage. Nominally it will only do up to 4 by 6 or so, but if you put the stock on the other side you can cut slices off up to about 6.5". I need a similar blank, possibly of something cheap and readily obtained like home cast mazak to make the drum for the wire with the dividing holes. For some machines, where slides are built into the gear or the shape is otherwise more complex, a friendly foundry would be helpful. Actually I suppose if the reason for cutting a gear is wear, the old gear could be fitted with a suitable ring to cut the new teeth in. regards John ------- Date: Mon, 13 Oct 2003 19:42:56 -0000 From: "stevenson_engineers" Subject: shaper cut gears I have been doing a lot of thinking about cutting gears this way. It's not new there were some attachments out there at the turn of the 20th century to do these on a shaper. The whole operation was also resurected in the 50's in an article in Model Engineer. I have mentioned this before. Recently I came across some old Victorian gear cutting books [ Have I mentioned I collect books ] In one of these there was a crude method to also generate bevel gears from a rack. This got me thinking and doing some limited maths and it looks as if this can also be adapted to a shaper using a single point tool. The real proof will be in actually cutting a pair and blueing them up for fit. With this in mind I had a quick look around and bought this today http://tinyurl.com/qrvo Initally I want to reproduce the old Model Engineer layout and do a few spur gears to prove the whole setup. I then hope to do a couple of simple bevels, again to prove it, but the whole aim is to CNC this so that the whole operation can be made automatic. It won't be fast but it's biggest claim to fame will be it can cut ANY range of gears from one simple single point tool costing pence. John S. ------- Date: Mon, 13 Oct 2003 11:20:25 -0700 From: k6sufx~xxdirecway.com Subject: Re: Re: Clock Wheel Cutting - What's Needed? To replace a clock wheel tooth, you cut off the broken section, undercut the rim to accept a new piece of brass, solder in place and recut the tooth. A file will do the job by making a tracing of the good tooth form and stick it on the "new" tooth material and go at it with a file. Only recomended if you don't have wheel cutting equipment or skills as usually easier to just make whole new wheel. ------- Date: Mon, 13 Oct 2003 18:40:43 -0000 From: "n2562001" Subject: Re: Clock Wheel Cutting - What's Needed? Bill: You will need the mill and either a indexer or a rotary table to index for the teeth. ( The cnc rotary table is really nice) You will find that it will simpler to build your own wheel arbors as they will all be different sizes. You can use either standard cutters or make single point cutters. The problem with cutters is that no matter how many you have you will never have the right one. I would only purchase what you need when you need it. When I cut teeth I set the mill head horizontal with the nose to the right side. I then mount the rotary table face vertical and parallel to the rear right side of the mill bed. This way the teeth can be cut at the top of the blank in the open where you can see what you are doing. Jerry Kieffer ------- Date: Mon, 13 Oct 2003 19:56:51 -0000 From: "n2562001" Subject: Re: Clock Wheel Cutting - What's Needed? > Can you describe what's used to hold the wheel blank/disc to the > rotary table? Bill, Generally use .750" brass or steel held in the three jaw chuck. I first cut the arbor to fit the wheel on the lathe and then transfer the chuck and arbor to the rotary table. Make sure the arbor is long enough for the cutter to clear the chuck jaws. Jerry Kieffer ------- Date: Mon, 13 Oct 2003 20:08:35 -0000 From: "platem" Subject: Re: Clock Wheel Cutting - What's Needed? Here's a link to a couple of pictures I posted on the CNC Sherline forum for my gear cutting setup using a Sherline lathe. If you have a lathe and no room for a mill, like I do, then gear cutting is still possible. http://tinyurl.com/qs3d Mike Plate' ------- Date: Tue, 14 Oct 2003 21:17:13 +0100 From: "Mark Howard" Subject: RE: Re: Clock Wheel Cutting - What's Needed? As others have said, the basis is to cut out the damaged teeth and solder in a new blank piece into which the new teeth are cut. It is, however, important to consider the load the wheel teeth will need to take. Wheels near the motive force obviously carry a much bigger load than those near the escapement. It is good practice to 'dovetail' the new teeth into the wheel. I.e. make a really strong mechanical joint before soldering. This is imperative on wheels that take a high load. In some areas, such as spring barrel teeth it may be better to cut a whole new wheel rather than trust a repaired set of teeth (particularly as the damage caused to the rest of the movement can be severe if spring barrel or great wheel tooth 'lets go). Thornton cutters are expensive (very good, but pricey). For the odd damaged tooth, I would make a single point cutter. If you buy a cutter for one or two teeth, you can bet you will hardly ever need to use that cutter again. Even for making whole wheels, if it's only occasional, I would still opt for single tooth cutters. If you're building a whole clock, it may be worth buying the cutters you need. It's worth considering that single tooth cutters don't handle pinions well (if at all), so you are probably forced to buy the proper cutter for pinions (these are different to wheel cutters, and so can't be used for both). Clock wheels are held on mandrels, usually held in a chuck on a dividing head or rotary table. Again, mandrels are best made to suit (practically every clock wheel will have a slightly different hole diameter). The other thing to consider is that the wheel, when held on a mandrel, will need to be supported by a thick washer on each side, the diameter of which, should just leave the tooth depth unsupported - again these generally need to be made to suit the wheel diameter. I hope it helps. Regards Mark Howard ------- Date: Tue, 14 Oct 2003 20:32:56 EDT From: tadici283x~xxcs.com Subject: Re: Re: Clock Wheel Cutting - What's Needed? You can make many a fixture with the use of wood, nothing wrong with that, use the lathe that you have to true the wood mandrel and you can center the blank that is larger turn it down to size and use a cutter, (single point works great) and simply cut through the entire fixture, this is without a doubt cost effective and many class clocks have been made this way (one author on the web calls oak poor man's alumin.) another way to hold and cut gears is to cut along a solid rod that is centered and part off gears as you need them. (useful for some gears) The important concepts here are 1. keep everything straight and true, and supported. 2. Use sharp cutters of the correct size needed (you will have to make that, because as Murphy states you will never have the right cutter when you need it and never use it again) and 3. Have a method to keep your gears well spaced. (I use a Sherline CNC rotary table now.) On the subject of soldering, a purist would never have any solder in any movement gears, even though it is a tested, taught method, it really depends on if you want to make a living fixing clocks or hobby repairing clocks. Chris of Bradenton FLA ------- Date: Wed, 15 Oct 2003 19:58:49 +0100 From: "Mark Howard" Subject: RE: Re: Clock Wheel Cutting - What's Needed? >>> "On the subject of soldering, a purest would never have any solder in any movement gears, even though it is a tested, taught method, it really depends on if you want to make a living fixing clocks or hobby repairing clocks".<<< It is a choice of evils. What is better: a soldered wheel tooth, a brand new wheel or a clock that doesn't work? The brand new wheel is just as abhorrent in an otherwise original movement. What is the alternative? I was taught professionally and have, in the past, been a professional repairer (semi-pro now as 'pro' doesn't pay the bills as well as I'd like) but no-one has offered a suitable alternative. Regards Mark Howard ------- Date: Wed, 15 Oct 2003 11:47:04 -0000 From: "John Shadle" Subject: Re: Clock Wheel Cutting - What's Needed? I've made now 11 clocks from scratch, now working on 12 and 13. Go to my website, and you can download an article on making fly cutters to cut gears. There's also a page on building my version of a clock wheel retoothing fixture -- cheaper than $350. John B. Shadle, CMC Online Clockbuilding: http://onlineclockbuilding.com Clock photo gallery: http://onlineclockbuilding.com/gallery ------- Date: Wed, 15 Oct 2003 18:48:00 -0500 From: "Al Lenz" Subject: RE: Re: Clock Wheel Cutting - What's Needed? Bill, the fly cutter should work O.K. in theory, but the tool is mounted at about a 10 deg angle. That would certainly complicate grinding the proper profile and the set-up. Sherline makes a P/N 3217 Gear tooth cutter holder which is very similar to the fly cutter except the cutter is held perpendicular to the axis. I would suggest getting it for gear cutting. al ------- Date: Thu, 16 Oct 2003 21:24:10 -0000 From: "Art Volz" Subject: More Gear Cutting Stuff Join http://www.groups.yahoo.com/group/mwmills2 to view some really good files on gear cutting, making gear cutters and gear fly cutters, and sharpening and honing gear cutters by "Duplex". Them check out the articles on gear cutting machines, especially the Jacobs hobbing machine for which castings are available from: http://www.collegeengineering.co.uk/gear_hobbing_machine.htm . Not much message traffic from the "members", but GOOD files. Art (Houston) ------- Date: Fri, 17 Oct 2003 22:59:41 -0000 From: "dreilanderecht" Subject: Shapening gear cutters Art, When my gear cutters eventually need sharpening, I will do it with the same set up used for cutting gears...except the cutter will go on the mandrel instead of the gear. Then on the milling spindle I will fit a small grinding wheel with a flat face and a bevelled edge, set up such that the flat face will cut a radial face on the gear cutter. The bevelled edge is so it will clear the back of the cutting tooth ahead. Then the gear cutter can be stepped around and an identical cut taken from each cutting face. This leaves them all the same height. But I suspect that with the quantity of gears I am likely to cut, and with the likely choice of materials (cast iron or steel) they should last quite a while. regards John ------- Date: Fri, 17 Oct 2003 20:36:21 +0100 From: Peter Harrison Subject: Re: Gear Cutting Hob Here is how I made a cuter for some spur gears. Hope it is of some help. http://homepage.ntlworld.com/peter_harrison/workshop/gearcutting/index.htm Pete Harrison http://micromouase.cannock.ac.uk/ ------- Date: Sat, 18 Oct 2003 10:52:04 -0400 From: "Ern & Anneke Grover" Subject: Re: Gear Cutter Flycutter style. I recently purchased a wheel cutting fixture from S. Larose, Inc. (www.slarose.com) for around $600. It fits on the Sherline Milling table very nicely. It's made by David Lindow in Pennsylvania and very ruggedly built. With it comes a very good assortment of index plates. The headstock receives a drawbar and fixture to hold the wheel in place, but the drawbar also accepts Sherline collets. It does a rather nice job. Though David marketed the fixture with wheel/pinion cutting for the clockmaker in mind, you can do a variety of gear profiles on it depending upon the cutter, of course. Pictures available upon request. Ern Grover, As Time Goes By 26 Webster Street, Springvale, ME 04083 207-490-3500 / http://www.timegoes.com ------- Date: Fri, 5 Dec 2003 22:36:52 -0600 From: "jerdal" Subject: Re: Gear cutting > I have the plans for the Atlas/Craftsman gear cutting attachment for > the 6" lathe. Can this attachment be used to cut BEVEL gears using > the lathe change gears as an index? Craig I'm not familiar with the attachment, but if you can tilt the blank to the right angle and turn it at a slight angle either way from the normal position you should be able to. I have done it on a 7B shaper. The teeth are cut as normal all around. Then the blank is swung a small distance, and one side is shaved. Then swung the other way and the other side gets shaved. That's it. I don't know if you can do that on the adapter, but that's what is done. Its all in "Gear cutting Practice" by Colvin and Stanley, available from Lindsay Publications Inc for a reasonable price. Jerrold ------- Date: Sat, 10 Jan 2004 18:14:37 -0000 From: "kendall" Subject: Re: Atlas 6x18 > Also, has anyone cut their own change gears for their 6x18 lathe? I have cut my own gears ,for the 618, on the 618, it's not all that difficult, I used brass and aluminum, as that's what I had. I don't have the 618 anymore, so can't help you with tooth counts and diameters, but can tell you the routine. Basically what I did was to turn stock down in steps, with a work space between them as wide as the gear, starting with the largest gear at the chuck, and going on to the smaller gears. Once you have the blanks set at the right size, cut a tool bit to the same shape as the teeth on one of your gears, mount it in the toolholder sideways, it has to be centered on the centerline, not as for cutting with the top edge on centerline, then it's time to do some calculation, because I don't remember what gears I used, and defintely not the calculations. but indexing off the gears in the headstock you can get the right tooth counts on the blanks. I used the bull gear index holes, and one or two more gears, any way once you get the teeth count, feed the bit into the blank slowly sideways with the handwheel, until all the gears are cut, takes a while when you have to make a lot, then bore them through as they sit, part them off, and remount them seperately in a fourjaw, to finish the sides, and center holes (locater 'ears' done the same as the teeth). You can do the entire process with seperate blanks, just make sure it's done as much as possible at one setting. Also it helps to turn a depth line on the gear face so you can make the teeth deep enough the first time. I don't know how long the aluminum lasts, as I traded off the lathe a year later, but I know that other brass gears I've made have held up pretty well. ken ------- Date: Sat, 17 Jan 2004 03:38:46 -0000 From: "davideggy2" Subject: Re: Rotary Table Design - Design Killed by High Cost --- In taigtoolsx~xxyahoogroups.com, "Del Stanton" wrote: > Does anyone have a good source of worm gear sets with 90 to 180 > reduction ratios at a more reasonable price? Project abandoned. Just a thought, why not make a worm gear? I've done it (just to try the concept) in 3/8 UHMW plastic and 5/16 phenolic. Used a 3/8-16 spiral tap (fast spiral) in a drill chuck mounted on the spindle. The gear blank was drilled 1/4" and mounted on a block of wood on the cross slide so it was free to rotate and supported well. Turn the lathe on and feed the blank into the side of the tap and watch the gear go around. At a certain depth, the teeth are perfect. Too deep and you have to go another tooth. Kinda hard to explain, but simple to do. Just use a 3/8-16 threaded shaft for the worm. Got the idea here: http://www3.telus.net/gwolanski/Gearcutter.html I use the formula: Dia of blank = # of teeth desired / 16 tpi (tap) / pi. In other words, 90 tooth gear: 90 / 16 / 3.1415 = 1.79" blank. 180 tooth gear: 180 / 16 / 3.1415 = 3.58". Tap size doesn't matter, just plug in your tpi. Has to be the fast spiral, tho, so there's always teeth engaged in the blank. I can post a picture of the setup if you like. Hope this helps, Dave ------- Date: Thu, 12 Feb 2004 15:27:49 -0000 From: "throwawaytip" Subject: Re: Gears and zamac - other choices [atlas_craftsman group] I found all of the Zamac parts on my QC54 to be unsatisfactory and have been replacing them over the years. The first to go were the gears in the train from the spindle to the input of the QC box. I replaced the gears, including the one on the spindle, with alternating bronze and Micarta (Tufnol if you are in the UK). Micarta is a fibre reinforced phenolic resin material much used in the electrical industry for its good insulating properties. It machines well but smells a bit. This combination wears well and runs quiet at high spindle speeds. I also replaced all the gears in the apron, both spurs and bevels, but this time all in steel. If you have the ability to cut gears in your own shop I'd recommend the bronze/ Micarta combination. I've also replaced some of the steel gears in the QC box to get rid of a pattern when taking finish cuts (previous owner had managed to jam the QC box and distort a couple of teeth). In this case I stuck to the Atlas choice of steel for the QC gears. ------- Date: Wed, 24 Mar 2004 18:26:48 EST From: n8as1x~xxaol.com Subject: Re: Broken Gear Teeth 3/23/2004, r7734gx~xxhotmail.com writes: > The backgear on my > lathe has some missing teeth. A replacement part may be close to > impossible to find. The choices are repair or build from scratch. > Any comments or hints about building up metal to replace missing > teeth on cast iron gears? Cutting the teeth once the metal is back > would not be a problem. What would be the best way to deposit metal > back on the gear body? Is this OK to do? Thanks in advance for i just brazed up & recut a new tooth on logan 72 tooth gear ...u will need some kind of indexer for correct no. of teeth , I mechanically cleaned & filed an undercut (which probably didnt need, just an old habit), used one size larger tip than for welding , ..actually had to recut several as i got careless w/ torch & burned a few tooth tips ....build up more than u think necessary ....turning down on a driven mandrel works & cutting teeth on same works ..or make up a thrd mandrel ....u can grind a bit to correct form ,or buy a cutter from wholesale tool., traverse tool, victor mach.exchange ...circa $ 22 for 16 pitch..home depot /loews has rods,.walmart has borax for flux ...$ 4.00 box fills up a LARGE coffee can (cudnt locate my old 20 mule team can) .....lifetime hsm supply.... to be safe preheat a little & put in sand to cool ....i didnt ,& got a way w/ it ,but u may not .......there is simply more risk & difficulty welding up cast iron w/ minimal equip /experience & if u have to ask , "you is they"........u can protect nearby areas by burying part of gear in a refractory ....sand/plaster mix ......dental labs routinely use this for delicate torch repairs on fixed bridges ,partials .....& dental supply houses have it available ( at least they did 25 yrs ago ) best wishes docn8as -------- Date: Wed, 24 Mar 2004 22:21:33 -0000 From: "carbure2003" Subject: Re: Broken Gear Teeth I am in the process of rebuilding a old South Bend 10K. When I bought it I didn't notice a gear teeth was broken on the bull gear on the spindle. It was fixed by the previous owner in a really simple way. The broken tooth was filed to the root diameter. A couple holes were drilled and tapped in the line of the missing tooth. Screws were fitted and glued in the holes, then cut to the outside diameter of the gear. The work was finished with a small hand file, giving the involute gear teeth profile. It runs smooth, no noticable noise when the lathe is running back gear engaged. The job is not perfect, but it works. No heat involved. I would not do it for more than one tooth missing. If the gear is made out of cast iron, bronze brazing will fill the gap if you want to apply heat. Then, it needs to be machined and milled with a gear cutter. There was an article in Home Shop Machinist Sept/Oct 2002. on this topic. It would be interesting to kmow the manufacturer of your lathe. Guy Cadrin Gatineau, QC Canada ------- Date: Wed, 14 Apr 2004 06:06:44 -0000 From: "sauer38h" Subject: Re: DIY Dividing Head Question --- In mlathemodsx~xxyahoogroups.com, xlch58x~xxs... wrote: > If you think about it, with high accuracy parts and good > lubrication just about any worm gear can work in reverse. This is incorrect. A worm gear set with a locking ratio - which is nearly all of them - will strip before the worm will rotate under reverse load no matter what the lubrication is. This is one of the useful features of worm gearing. Locking ratio worm gears have tooth contact at less than the locking angle. The locking angle varies with different materials and lubricants, but is never zero. Locking action occurs in worm gearing because the contact between teeth is entirely sliding contact - there's none of the rolling contact characteristic of spur gears with involute teeth. Spurs gears do not have locking ratios. The static coefficient of friction is the sine of the locking angle. It can be measured by putting a block of one material on a ramp of the other, and tipping the ramp up until the block slides under its own weight, or any other vertical force. The angle at which that happens is the locking angle. Strictly speaking, this is Coulomb or "dry" friction. The word dry is misleading - it does not mean unlubricated. It differentiates this friction mechanism from viscous drag, the domininant drag or "friction" force when a fully-developed hydrodynamic film separates the parts. Worm gears can be modified to be reversing by increasing the lead of the worm. To get enough lead you'd have to have something like a 4- tooth gear, which won't work for geometrical reasons. Some multi-lead worms can be reversed. They're not common - in thirty years in engineering I've yet to see one. The other way to make a reversing worm gear is to offset the axis of the worm and move it down toward the axis of the gear - in which case it becomes a spiroid or hypoid gear set, and isn't called a worm gear anymore. ------- From: "Nigel Spurr" Date: Fri Apr 16, 2004 1:42 pm Subject: Re: [atlas_craftsman] Rack and pinion From: "John Ladd" wrote: >> I would like to build the 3D slide viewer featured in the Oct/Nov Machinist Workshop. It requires a rack and pinion similar in size those used in camera focusing mechanisms. Does anyone know where I can buy a rack and pinion? I'm definitely not capable of cutting my own at this point as I only recently bought my first lathe, a 101 07301. Thanks. << Try hpcgears.com or, if the feed is not too critical, a length of chain can replace a rack and a sprocket a pinion. Use standard and cheap cycle parts or even toothed belt can be used. Alternatively, a screw and nut can be used for a linear drive. Very cheap! Have fun! Nigel -------- Date: Fri, 16 Apr 2004 11:58:45 -0700 From: "Weight, John" Subject: RE: Rack and pinion W.M.Berg Inc has a complete range of things that would suit you......Their Master has a lot of info and theory too. www.wmberg.com Ph 1-800-232-BERG John W San Francisco ------- Date: Sun, 18 Apr 2004 01:51:58 -0000 From: "sauer38h" Subject: Re: Rack and pinion A very small rack & pinion might be hard to find. For general engineering R&D I used to buy racks, gears, couplings, etc from PIC, Small Parts, SECS, or McMaster-Carr. Generally I'd order from whoever's catalog I could find lying around. I rarely bought from Winfred Berg because I always lost their catalogs but some of the other engineers swore by them. Now in the Internet era I don't have to hunt for the catalogs, as everybody's online. Try www.smallparts.com, www.pic-design.com, www.prosecs.com, www.wmberg.com, or www.mcmaster.com. I know that McMaster is easy for private persons to buy from, you don't need accounts or purchase orders, just order online with a credit card. I haven't bought anything that way from the others, so you'll have to poke around their sites to see what's what. wfw ------- Date: Tue, 20 Apr 2004 03:27:02 -0000 From: "n5fee" Subject: Program to select Gears Here is a link to a couple of programs I have been using. Years ago, I calculated a bunch of gear setups to yeild a lot of odd threads per inch that were not listed in the lathe manual. I did this using a Data General main frame computer at work. When personal computers came along I made up lotus spread sheets to do the same thing for another lathe I had accquired. A year or so ago I ran on to this program that is really neat. There are three variations at the link listed below with instructions for each. The instructions needs to be opened with Microsoft Word. The other files are zipped executable program files. I entered the gears I have avaliable for each of my lathes and saved the setup for each one in a different folder. This makes short work of picking gear possibilites for various threads per inch or mm per thread. http://www.lathes.co.uk/screwcutting/ Dallas Shell -------- Date: Tue, 20 Apr 2004 14:28:07 -0400 From: "David G.Sampar" Subject: RE: Re: Program to select Gears >>> Dallas, the text that goes with the programs mentions a geartrains.bmp file. I've tried Google, and cannot find the file anywhere. Have you seen it? Regards, Ed Bailen <<< Download the files from the site below and rename them: threadstext ---> threadstext.doc generalthreadscalculator1 ---> generalthreadscalculator1.exe generalthreadscalculator2 ---> generalthreadscalculator2.bmp ------- Date: Wed, 21 Apr 2004 03:01:14 -0000 From: "n5fee" Subject: Re: Program to select Gears Ed, sorry, I mis-led you on what downloaded from the site. David's message has the correct instructions for renaming the files. Thanks David for posting the correct way to rename the files. The image of the gear train was not too helpful to me. You just have to try the combinations of gears on your machine to see if they will physically fit in the space you have. Dallas Shell ------- Date: Thu, 2 Dec 2004 23:10:09 EST From: n8as1x~xxaol.com Subject: Re: Involute gear cutters hugh345x~xxadams.net writes: >Victor machinery had involute cutters in their last flyer $15 - $25 each got an xcellent 14 pitch cutter from them couple years ago ...made in poland...travers cutter was from china ....worked as well ,but not as pretty...course for light & adjustable change gear load ,almost anything of correct pitch wud work...Am.machinist handbook 1921, shows a method for constructing a single curve gear tooth for all gears that normally require 8 cutters, ...w/ a tad clearance ,looks like it wud work w/ any involute u have...i have cut gears w/ cutters 2 numbers smaller than spec.(too sorry to make a single tooth cutter & too cheap at the time to purchase one) & they worked well as change gears ,one still being used as stud gear... gears have even been made w/ a rack cutter & opening up the spacing, marking & filing interference out till they close up as needed... best wishes docn8as ------- Date: Fri, 03 Dec 2004 05:27:36 -0000 From: volzmechatronicx~xxyahoo.com Subject: Victor Machinery Exchange URL: Re: Involute gear cutters http://www.victornet.com for on-line catalog. Art (Houston) ------- Date: Wed, 23 Mar 2005 14:54:24 -0800 (PST) From: R Thomas Subject: Re: cutting gears [taigtools] You can also use an arbor between centers with a gear cutter attached. The arbor and cutter will have a simlar configuration to a horizontal mill. The indexed gear blank will attach to the cross slide and move back and forth into the cutter. I don't know if the Taig is large enough for this but it worked great on a 10" Logan. Richard ------- NOTE TO FILE: A thread starting with a message dated 12 Apr 2005 "Re: Gear Cutting" by Tom Benedict was moved to the head of this file as it provides an excellent general introduction to cutting gears, and other kind folks have provided more references. ------- Date: Fri, 23 Sep 2005 14:24:41 -0000 From: "John Shadle" Subject: making clock escape wheels. [taigtools] I've done a mini-article on making clock escape wheels, using my Taig mill. You can see it at: http://www.onlineclockbuilding.com/fly/fly.html John ------- Date: Sun, 25 Sep 2005 01:52:37 -0000 From: "John Shadle" Subject: Re: making clock escape wheels. >Thanks for the article, John. Got a question for you: You said to >run the cutter as fast as your mill will go (and since you're >describing this for a Taig mill, you know how fast that is!) How fast >do you feed? Tom Yep, I've been running flycutters at the Taig mill's top speed. I feed slowly. A flycutter will buzz as it cuts. If it clatters, then something is wrong, such as a dull edge or no clearance behind the edge. Thanks for your interest. John ------- Date: Mon, 26 Sep 2005 13:01:28 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Re: Re: making clock escape wheels. 26/09/2005, benedict-listx~xxhawaii.rr.com wrote: >> One last question: I know clock wheels tend to be thin compared to involute power transmission gears, but they still have thickness. Once you've fed to depth (albeit slowly) do you then make a pass through the thickness of the gear to get a nice profile? Or do you find only a plunge and retract to be required? Thanks, Tom << On Mon, 26 Sep 2005, Tony Jeffree wrote: > Tom - Unless you are cutting pinions in steel, it is usual to take the cut at a single pass; you "depth" the cut by marking the edge of the blank with layout blue (felt-tip pen) and make 2 cuts a tooth apart, examine the "witness" left on the tip of the tooth, increase depth if necessary to *just* remove all of the witness mark, then cut all teeth at full depth. So the easiest arrangement is to feed the cutter in from the side once the correct depth has been found. Regards, Tony < Thanks, Tony. AAAAAAH! Got it! So you're not feeding as a plunge, you're feeding across the work at a consistant and unchanging depth. Tom ------- NOTE TO FILE: John Shadle's site has a wealth of instructions, with excellent supporting photos, on how to carry out all sorts of machining tasks, including making your own gear cutters and gears. An absolutely must-site to visit (often). ------- Date: Mon, 23 Jan 2006 18:31:24 -0000 From: "jptrueblood" Subject: Gear Cutting [Metal_Shapers] I looking for a approach to cutting 48 pitch involute spur gears on a metal shaper. I have an Atlas 7B. I do not have a set of centers. How difficult is it to make a jig or a set of centers from scratch to cut gears with? Or I should say, does anyone have a set of plans or a description for making said jig or centers. Thanks, Jeff ------- Date: Mon, 23 Jan 2006 21:42:55 -0000 From: "Don Kinzer" Subject: Re: Gear Cutting > How difficult is it to make a jig or a set of centers from > scratch to cut gears with? You might get some ideas from this page: http://www.kinzers.com/don/MachineTools/index_centers Don ------- Date: Mon, 23 Jan 2006 23:53:01 -0000 From: "Irby Jones" Subject: Re: Gear Cutting Jeff: Have you looked over the gear cutting files in the sister group? http://finance.groups.yahoo.com/group/Metal_Shapers_Pix/files/ There are a couple methods presented there that are helpful. One method (shaper gear cut.pdf and second article.pdf) has the plans for a gear blank holder and the associated hardware to cut involute gears using a simple straight-sided tool. But it's rather involved. The other method (under folder Involute Cutters) shows how to make the involute-shaped cutters, and then you would need a way to hold and index the blanks. The most difficult part of indexing the blanks would seem to be getting an accurate gear or index plate to use in indexing the blanks. Most people seem to end up using an indexing head, but if you search around you'll find sometimes a simple holder and a gear or index wheel can be used. I don't have a specific set of plans to point to, though. One simple arrangement is shown here: http://www.metalworking.com/DropBox/1902_mill_2.JPG Irby ------- Date: Mon, 23 Jan 2006 18:49:47 -0600 From: J R Williams Subject: Re: Re: Gear Cutting Buy or build a simple indexing device and purchase a standard gear cutter, around $25, and mount the cutter on a tool holder and get busy. JRW ------- Date: Mon, 23 Jan 2006 23:25:37 -0600 From: J R Williams Subject: Re: Re: Gear Cutting "Jason J" wrote: > What pray tell is "a standard gear cutter"? Involute gears are such > that you would need a different "cutter" for each diametrical pitch, > each pressure angle, and each tooth count/diameter of gear to get > it right. Jason: A set for each pitch is eight cutters. JRW ------- NOTE TO FILE: I suspect JRW's initial answer assumed the cutting of one particular gear, for which only one cutter is needed. Each cutter can do a small range of gear teeth. Obviously more cutters are needed if a diverse set of gears are going to be cut. But sometimes you only need to replace one busted gear, and your setup cutting needs are then relatively cheap compared to buying a commercial gear replacement. ------- Date: Tue, 24 Jan 2006 19:24:17 EST From: n8as1x~xxaol.com Subject: Re: Re: Gear Cutting J R Williams wrote: > Jeff: Try Wholesale Tool Co. (www.wttool.com). They list both > 14-1/2 and 20 degree cutters. JRW 1/24/2006, volzmechatronicx~xxyahoo.com writes: > I buy mine from http://www.victornet.com > ...good stuff-skis from Krakow. have bought both ..polish stuff is finished better, but chicom worked just fine for cutting bunch of 14 pitch chnge gears ...wholesale tool has a bunch of 40& 50% off cutters ...gets interesting ...FWIW ...i have cut a few gears w/ cutters for lesser # teeeth...(for shame) , but seem to work just fine ...probably even cutter for more teeth wud work w/ the adjustable center to center of change gears ...(am now ducking behind shelter) best wishes docn8as ------- Date: Wed, 25 Jan 2006 05:03:49 -0000 From: "Art Volz" Subject: Re: Gear Cutting "Jason J" wrote: > I think that is what I was saying. An eight cutter set won't do > a 16 tooth and a 127 tooth gear. J--An 8-cutter set WILL cut all gears of a particular DP. For instance, the #7 cutter will cut a 16-tooth gear and the #2-cutter will cut a 127-tooth gear. To see what numbered cutter, of an 8-cutter set, can be used for what tooth gears see chart at "gear cutters" at http://www.victornet.com which apparently you haven't looked at yet. Are you thinking of cutting a 127 tooth gear for perhaps adapting an inch lathe to cut metric threads? You'll need more than a clone B&S 0 semi- universal indexing/dividing head as it won't directly index 127 spaces. You would have to adapt it with two indexing plates and use "Compound Indexing"--a method which takes two plates, both indexed. A universal head -- the expensive kind -- can index directly 127 spaces as it has its own change gears that allow for a much broader range of indexing... Art ------- Date: Wed, 25 Jan 2006 13:17:06 +0800 From: "Hubbard, Roger M SARAWAK-EPA-T-WTE" Subject: Re: Gear Cutting Guys, I have a small workshop book entitled Gear cutting. It shows how gears, involutes & convolute & indeed racks can be cut either by using a shaper or a lathe. (Sorry, wash my mouth out with soap & water, I mentioned the L word!) Whilst I don't have the book with me in the office, I recall that they talk about photocopying a page of cutter details from Machineries hand book to get the basic profile, then scaling in up. A single point cutter is then ground up to suit the cutter profile from either HSS or Drill rod. Surely, going to the expense of a multi tooth cutter, plus making up a special holder, is going against the basic principles of shapers! (KISS) Regards R ------- Date: Wed, 25 Jan 2006 06:12:37 -0000 From: "Art Volz" Subject: Re: Gear Cutting Roger-- Are you refering to Alfred W. Marshall's "Gear Wheels and Gear Cutting", a MAP Technical Publication? There is a section in that book that discusses the cutting of gears on a lathe & the cutter used appears to be a standard gear cutter. I looked rapidly again thru my copy, but didn't see any discussion of grinding single point cutters or using "Machinery's Handbook" to get a profile from which to derive that of the cutter to be used. Could have missed that part in my haste...and I only have the 1975 edition. Maybe an article in "Model Engineering"? Somewhere, I have a copy of R.H. Cooley's "Complete Metalworking Manual" which has a short illustrated chapter on hobbing gears on a lathe, how to make and install the hobbing mechanism, and how to make your own hob. The 1978 print by Arco Publishing has ISBN 0668014067. Several years ago I made a shaper tool holder to hold and to index single teeth of a standard gear cutter. I used two 1/4-inch thick pieces of steel plate, flat-head screwed together, with a shank 1/2- inch wide x about 1-inch + wide to fit a tool post of that size. The gear cutter holding end had a 7/8-inch diameter hole that held a 7/8-inch bolt that clamped the cutter with a washer and a nut. Another small bolt, located at the root of one of the cutter's teeth, acted as the cutter indexer. When I looked thru my shop this afternoon, I couldn't readily locate this tool holder. While this toolholder appears to properly allow one tooth to cut at a time... and is simple to make and use...I never used it for two reasons: I needed to make a larger slotted tool post, which I never did, and I didn't want to risk a brand new Polish-ski cutter, the only cutter I had on hand with a 7/8-inch ID. Used cutters appear to be always for sale on eBay, and sometimes in the DP, PA, No. and ID desired. Art (Houston) ------- Date: Wed, 25 Jan 2006 09:00:42 -0500 From: "Mark Greer" Subject: Re: Re: Gear Cutting > Amazing isn't it, that, thanks to Brown & Sharpe, for well over a > hundred years machine shops the world over have been able to cut > gears regardless of what you think, using that basic set of 8 cutters. > Tom This is to go along with what Tom stated above. It came from the victornet website but can be found in any gear cutter manufacturers catalog. He is correct by the way. Mark >> High Speed Steel. 14 1/2° Pressure Angle. Radial Tooth Face. These cutters may be resharpened repeatedly throughout the entire life of the cutter, without changing the original cutting form. Diametral Pitch indicates the number of teeth in a gear per inch of pitch diameter. FOR EXAMPLE: to cut a 3" diameter gear with 24 teeth use a 8 Diametral Pitch, Number 5" cutter (24 teeth/3"=8 D.P., number 5 cutter is need to cut 24 teeth). Eight different cutters are made for each diametral pitch. #8 cutter cuts 12 teeth to 13. #7 cutter cuts 14 teeth to 16. #6 cutter cuts 17 teeth to 20. #5 cutter cuts 21 teeth to 25. #4 cutter cuts 26 teeth to 34. #3 cutter cuts 35 teeth to 54. #2 cutter cuts 55 teeth to 134. #1 cutter cuts 135 teeth to a rack. << ------- Date: Wed, 25 Jan 2006 21:12:23 +0000 From: Clive Foster Subject: Re:Gear Cutting Roger, Art Alfred Marshall's book in the MAP range was superseded by the similarly titled "Gears and Gear Cutting" written by Ivan Law. Besides being more modern in approach this book gives details of how to generate a single point involute gear tooth space cutter using a pair of disks to define the profile. Obviously you have to make the cutter from something soft enough to machine and subsequently harden it but, by all accounts the process works well and gives sufficiently good teeth for most applications. I've not studied the method but it looks as if you can tweak parameters to get the right shape for any specified number of teeth. The book was first published in 1988 and is no 17 in the Workshop Practice Series, IBSN-0-85242-911-8. Current publisher is Special Interest Model Books (www.specialinterestmodelbooks.co.uk) but you will find it under the imprint of MAP, Argus and Nexus depending on who then owned Model Engineer and the other hobby publications, I think Future have them for now. The saga is an amazing tribute to the inability of the "spreadsheet man" infested modern British business community to turn a profit out of a product in steady demand. Best to chomp the spaces out first with a roughing cutter so the involute shape only has to clean up. Gears cut by this method or for that matter with B&S cutters are not up to high speed high load jobs so you canna fix the gearbox in your car. I believe that the B&S cutter method sacrifices some of the centre distance spacing tolerance for true rolling contact inherent in the involute concept so, if the centre separations are a bit out you will get sliding contact and the associated wear and noise. Effect depends on how far from ideal the cut tooth is. Right in the middle of the range for each cutter its not a problem, meshing two gears from most distant ends of cutter ranges is more likely to create problems. Your ears are the best guide, if you make a pair assume that you will need to set-up a running in jig. Clive ------- Date: Thu, 26 Jan 2006 08:30:49 +0800 From: "Hubbard, Roger M SARAWAK-EPA-T-WTE" Subject: Gear Cutting Gents, we seem to be getting of the path of the original thread on this topic! Let's get back to basics: 1) Let's just admit it a shaper is not the "Ideal" machine to cut a gear on, be it straight toothed, involutes, convolute, bevel or helical, however...however, if it's the only machine you have & that's your bag, then yes, it can be done. However...it's not going to be 100% consistent with the required profile but it will do. 2) If you do decide to use a shaper to cut gears it's very likely to be a one off, hence time & production rate is not of the essence! 3) If it's a one off, we don't want to the expense of purchasing a rotary profile cutter & making a holding tool to fit it in the shaper. 4) Given that time is not of the essence we can make a single point cutter by grinding up HSS. (I say HHS, because the attached article gives some insight into using Drill rod for single point gear cutting.) 5) When I was a lad, as I've said before, I worked in a "Poor Boy" shipyard machine shop. On numerous occasions teeth would strip from the drive wheels of the overhead crane. What to lah, these were cast iron gears & unobtainium. So, remove the gear wheel, clean up the damaged area until it was flat, drill & tap the gear to take short pieces of threaded steel round stock. Weld up the gaps between the steel bolts as best you could. Shape the teeth as best you could to the original profile using a single point cutter...in a shaping machine. Then finish off with a file such that the repaired gear wheel meshed with the others. This was done numerous times & the steel pegs never broke, it was always another set of original cast teeth that broke. Please find below an example of a guy single point cutting gear wheels on a Milling machine, ops sorry, that's twice in one week, I mentioned the M word. But we all know that a shaper can do everything a milling machine can...right! http://www.aardvark.co.nz/pjet/gears.shtml Regards R ------- Date: Fri, 27 Jan 2006 19:59:42 +0000 From: Clive Foster Subject: Re: Gears... When using a shaper to cut gears it is possible to do the job by a self indexing method unless the gear is small. Idea is to start off with a straight sided gnashing cutter similar to rack form sized to leave enough meat on the teeth to put the involute curve on later. A blank of the correct radius is set-up with a two position indexing arrangement at some convenient position around the periphery. It's easier to follow WTHIGO if one indexing position is near to 180 degrees off from the cutter axis and the other is one tooth further around the periphery. Whether or not the first index position can be at 180 degrees depends on the number of teeth in the gear as obviously it must fall in line with a space on the completed gear. Start by gnashing the first space to full depth at any point on the blank. Rotate the blank until the gnash engages in the first index point and cut a second gnash. Then move the first gnash to the second index position which is one tooth width along and cut the third gnash. Now you have two proto spaces and one proto tooth on one side of the gear blank and one space on the other. Swing the blank round and use the two spaces and two index points to generate two more spaces giving you three and two. Repeat until all proto spaces are done; you may have to flip the gear and work from both sides to get all the teeth in. Finish off using the same procedure with an involute cutter. Method takes a fair bit of working out but I'm assured by "one who claims to have done it" that it's perfectly practical. I imagine that if you set the spacing of the two index points correctly you could get two new spaces each rotation rather than just one but just the thought of working that out makes my head hurt! Concerning the useful range of application of gears cut with B&S cutters, I can assure Tom that the unsuitability of gears simply cut to nominal depth with B&S cutters for high speed and high load applications is straight textbook stuff. That said high speed and high load is to some degree moveable feasts and the commercial gear cutter has a number of tricks which can enhance performance relative to simply cutting teeth to the specified depth. Many catalogue suppliers offered a premium range in which standard cut gears were shaved or otherwise reworked for more demanding applications. In any case high speed and high load usually requires gears designed for the application, often with tooth forms which are anything but standard involute. In Brad's case a B&S cutter won't help. Modern motorcycle gearboxes do not use standard involute form gears. Firstly you can't cram the required tooth count differs into the space and secondly they wouldn't take the torque. I do know that my rotary Norton destroys third gear on the Triumph 5 speed derived gearbox in about 60,000 miles whatever you do. In this older design, with teeth close to the involute profile, shaft deflection and other stresses from 90 odd HP and pretty much flat 75 ft lb of torque simply scrub through the hardening. If Brad has a defunct transmission he could use the old gears to do the indexing and to copy the tooth profile. He will also have to shape out the inside splines and drive dogs. As it's a Japanese machine the tooth profiles will be outlandish being stub teeth with modified addendum and dedendum with the involute contact being a product of two non involute curves. (You only need involute teeth if any gear has to run with any gear, for matched pairs you can be much more creative.) Having made the gears Brad will need to run the pair together in suitable abrasive media to lap and polish them as a matched pair before heat treating and hardening. He would also be well advised to have them coated. There are various nostrums which bond into the surface and not only reduce friction and wear but also reduce the stresses in the gear. John Bradley's book The Racing Motorcycle, A technical guide for constructors, has some useful gear info which I could pass on if Brad contacts me off list. HTH Clive ------- Date: 28 Jan 2006 04:30:30 -0000 From: atlas618lathe Subject: New file uploaded to atlas618lathe This email message is a notification to let you know that a file has been uploaded to the Files area of the atlas618lathe group. File : /spur gears.pdf Uploaded by : n1ltv Description : Spur gear technical and design data from Boston Gear (http://www.bostongear.com/) You can access this file at the URL: http://groups.yahoo.com/group/atlas618lathe/files/spur%20gears.pdf ------- Date: Tue, 11 Apr 2006 03:12:02 -0000 From: "vtdiy" Subject: Re: Atlas Shaper questions [atlas_craftsman] Michael Fagan wrote: > What kind of setup do you have? I occasionally have had the need to > repair gears that need only one or a couple of teeth recut. I am > interested in how others have approached this problem. > Is it a vertical or horizontal mill? Hi Michael, my gear cutting setup is quite simple: 1. I have a horizontal Atlas mill. 2. I have a $29.95 imported 5C spin collet holder. This will index to 1 degree via a 10 hole vernier peg against a 36 hole indexing plate. (I plan on drilling the plate for other indexing factors as needed.) I use a 1/2" 5C collet for a 1/2" expanding mandrel. (Assuming the gear has a 1/2" hole -- or larger if you bore it out later.) 3. I made a 1/2" expanding mandrel by first drilling and tapping the end of a 2-1/2" long piece of 1/2" dia. drill rod for a 3/8" pipe thread, then slitting the end twice (crosswise - 90 degree cuts), about 1/2" deep. Screwing a pipe plug in expands the end (because of the taper of a pipe thread) and holds the gear. I put a 1/2" collar further back on the mandrel where I want the gear to rest against. This is a Dave Gingery style mandrel. 4. For a cutter I grind a very short 1/4" lathe tool bit to the required tooth form by using an existing gear of the same pitch and approximate number of teeth as a gauge. You grind the tool to the shape of the space between the teeth. Since in your own case you are recutting a tooth on the same gear you can use that gear as a gauge. This takes a little trial and error with the bench grinder. A Dremel tool can help. A magnifying glass, too. Again, Dave gingery style. 5. I mount the tool in a short (6" x 5/8" dia.) boring bar I made by drilling a 1/4" cross hole in a length of 5/8" rod about 3/8" from the end. Then carefully filing it square to closely fit the tool bit with a small triangular file. I drilled the end in 1/4" dia and tapped for a 1/4 bolt to retain the tool bit. Also Dave Gingery style. I tend to do things ala Gingery, because I cast, scraped and built my first lathe from scratch following his book. I later built my own design milling attachment and boring table for it with vertical rotary indexing. And built a Tesla disk turbine, and other projects. I'm looking forward to using the Craftsman -- It's much larger than what I've been using these four years or so, and has screw cutting capability and a 4 jaw. I never got around to adding those to the Gingery lathe, though still plan to do so. Best Regards, Steve Redmond ------- From: "Earl Bower" elbowerx~xxaccess995.com Date: Tue May 2, 2006 7:50pm(PDT) Subject: Gear Cutting Attachment [atlas_craftsman group] I have just uploaded a copy of the Gear Cutting Attachment that has been requested. This is a copy of the Atlas Gear Cutting Attachment that I obtained from (a now long gone Company of Castings and Prints) Casting Specialities. It came with their power hacksaw castings/plans so you can cut your own gears. This matches exactly (have checked it against an original copy of the Atlas print, which is too large to scan and upload) but is in a smaller format. The only problem with using this fixture is that you must have the exact matching gear teeth to cut the gear you want. e.g. if you want to cut a 23 tooth gear then you must have a 23 tooth master. You will need Adobe 5.0 reader or higher to view. Hope this gives the information that was being requested. Also, Atlas (to my knowledge) never supplied castings for this fixture. You had to make your own. Earl Bower www.bowermachineandtool.com ------- From: "Russ R" k1hopx~xxyahoo.com Date: Wed May 3, 2006 10:57am(PDT) Subject: Re: Gear Cutting Attachment hi Earl, Interesting plans... I've just one question: How/where does one attach the "attachment" to the lathe? And how is it aligned/spaced so the cutting is in the right place on the blank (relative to the spindle)? If you can resolve this for me, I'm very interested in making one of these for my 12x24 Craftsman. Russ in CT ------- From: "John Burridge" John.Burridgex~xxfsmail.net Date: Wed May 3, 2006 4:46am(PDT) Subject: Re: Gear Cutting Attachment Hi to all, I have a link to the Raglan Machine Tools web site about gear cutting on a lathe with hobbing setups. http://ph.groups.yahoo.com/group/RaglanMachineTools/photos/browse/a770 yours John Burridge ------- Re: Mounting Sherline Rotary Table in Vertical Position [sherline] Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Sat Feb 17, 2007 5:08 am ((PST)) John Emmons wrote: > Good Afternoon David, > Back in December of 2006 you posted some picture of cutting gears on > the mill. I believe at that time I wrote you inquiring about > obtaining some additional information from you about the process of > cutting gears on the mill. If I remember corrrectly, you responded > indicating that you were going to be writing up the process with > pictures. > I am writing to inquire if you have had the opportunity to complete > the task of documenting the process of cutting gears on the mill? Is > the document available on the internet? If not, is it possible to > obtain a copy from you? > Thanking you in advance for your response, I am. > Warmest Wishes and God Bless, John Hello John: That was me. I don't know that I'm going to be able to produce a tutorial any time soon, I've had some distractions. However, if you have some specific questions, please post them. Here's a brief overview of what's involved: First consideration is what the gears will be used for. This will dictate the material, tooth form, and size of the gears which, in turn, will dictate the machining process. This will also determine whether it's advisable to make your own cutter, or to purchase one. If you're contemplating making gears for heavy duty, high-speed, powered machinery, the gears would probably have to be steel. They would typically be machined with an allowance, case hardened, then precision ground and polished to exact size. This may be beyond the realm of the possible for a home shop machinist. At the other extreme, light duty gears and clock gears are most often made of brass. Easily machined steel alloys and even plastics are also a possibility. If epicycloid or triangular tooth forms are usable, you can make a cutter. If an involute form is indicated, you can buy cutters. (This can run into some money depending on how many cutters you'll need.) Why don't we begin by you telling us what your gears are for? Then we can talk through the design and machining process. I can also post links to some useful and informative sites. Perhaps in this way we'll evolve a tutorial of sorts. Regards, DC BTW; I'm David C. Clark, there are quite a few Davids on this and related groups, including, I think, a David A. Clark. Not to mention an abundance of Jerrys. ------- Re: Mounting Sherline Rotary Table in Vertical Position Posted by: "Tom Bank" trbankx~xxpaonline.com Date: Sun Feb 18, 2007 8:51 am ((PST)) Another suggestion in learning to cut gears would be to start by cutting a few odd sized gears to add to the Sherline threading set. That's what I am doing. They can be made out of aluminum and a single point cutter can be fashioned from a 1/4" square tool bit with a Dremel tool and a cutoff wheel, or two or three 8^) I Xeroxed the two gears on either side of the tooth counts I wanted and pasted the cut-out of the space between the teeth onto the tool bit to get the form I needed. Draw a line down the middle of that space and right to the center of the center hole on the gear. Then cut a strip going out from the gear teeth to use as your pattern. Jerry Keefer tipped me off to cut the gear form straight back down the sides of the tool bit and then cut the front face of the single point cutter at a fairly steep angle (more than just 10 degrees) so you will be trimming or slicing with the tooth form instead of batting the blank with the whole edge of the cutter each time it comes around. Once that angle has been added to the tooth form, relief can be cut on the sides and the end of the cutter. When I got down to cutting gears, the first lesson I learned is that your setup has to be locked down tight. Surprise of surprises, on my first gear the teeth were slightly wider than the teeth on the gears Sherline makes,... except for the two that were ridiculously narrow. As Jerry Glickstein said, you have to be extremely lucky to cut a usable gear on your first try. The cure for uneven teeth is: 1.) On Sherline threading gears, make a key for the keyway in the gear blank and backer pieces that must be put on either side of the gear as it is being cut. Slot the gear mount to receive this key. 2.) Use the set screw in the 3/8" end mill holder with a dimple drilled into the gear blank mount to lock that mount so it can't twist (and so you can get the mount out of the end mill holder when you are finished). 3.) Screw that end mill holder onto the rotary table tight. 4.) Lock the rotary table with the set screw for every tooth you cut, and... 5.) Every movement on the mill that isn't being used in the move you are making should (must) be locked down tight. In relation to the above, the Z axis needs to be locked and it needs to be set with the cutter at exactly the center line of the rotary table. Even a slightly off center cutter will make teeth with a strange and obvious slouch to one side. My solution to getting the right setting was to make a screw-in center for the rotary table with an inch long, sharp tipped projecting pointer. To lock the Z axis, I made a clamp for the Z dovetail that fits up underneath the saddle. Note that this clamp requires a small block above the actual clamp to get past the gib and make contact with the bottom of the saddle. Beyond that, I made a simple spread sheet to give me the degree readings for each tooth and then checked them off as I made the cuts. The final cuts of one or two thousandths on each of the teeth were made in a second pass to be sure that all the teeth were completely even. Also, I used a soft wax-like tapping lubricant and coated the front tooth part of the gear blank with it rather thickly. The brand I have is Tap-Ease, which comes in a pencil like stick. I got it from MSC. I would venture that if you couldn't find that product or something like it, bees wax would be very similar. Just my take on the gear cutting adventure. Regards, Tom Bank ------- Re: Mounting Sherline Rotary Table in Vertical Position Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Sun Feb 18, 2007 11:44 am ((PST)) Good Take, Tom! and .02 cents more.... For less wear and tear on your finish tool, make a "roughing tool" that leaves about .005-.007" all around to "clean up". Use the same coordinates. You can also incorporate Jerry K's "shearing action" suggestion. Regards, Jerry G (Glickstein) ------- Re: Mounting Sherline Rotary Table in Vertical Position Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Sun Feb 18, 2007 12:50 pm ((PST)) > and .02 cents more.... And my 2: > 2.) Use the set screw in the 3/8" end mill holder with a dimple > drilled into the gear blank mount to lock that mount so it can't twist > and so you can get the mount out of the end mill holder when you are > finished). I turn a 10 degree taper on a longer set screw, and use a 10 deg taper end mill to make a matching seat in the gear blank mount. This is a good technique when you need a shaft to be absolutely fixed in all directions, yet easily removed and replaced many times with no wear and tear anywhere. DC ------- Re: Mounting Sherline Rotary Table in Vertical Position Posted by: "Jerry Jankura" toolzngluex~xxsbcglobal.net Date: Sun Feb 18, 2007 11:46 am ((PST)) Hi, Tom: Could you comment more on the techniques that you used to make your cutter - how you held the tool, how you marked the cutter blank, etc. Jerry Jankura Strongsville, Ohio ------- Re: Mounting Sherline Rotary Table in Vertical Position Posted by: "Tom Bank" trbankx~xxpaonline.com Date: Wed Feb 21, 2007 3:29 pm ((PST)) Hi Jerry, I hate to admit it, but I just glued the Xeroxed template of the space-between for the gear with the higher number of teeth (i.e., what I wanted to cut plus 1) to the tool bit. That gear has the narrower, or rather straighter sided, spaces between the teeth. I then held the "negative" outline of the wider space-between for the "minus 1 gear" (in other words, the cutout outline that has the two halves of the gear teeth on either side of the space) up to the glued on image to give me a feel for the difference between the two and tried to split that difference. I just held the tool bit/cutter blank in my left hand and the dremel flex shaft tool with the cutoff wheel in my right. I admit that my freehand work may be a little better than some others, I have taken 1st place in NMRA modeling contests, but basically I just carved the shape for my single point cutter freehand. As I said in my earlier message, the beauty of starting with the aluminum Sherline threading gears is that they are far less demanding than trying to cut a gear from brass or steel that will run at 1,000 rpm for hours at a time and/or be expected to carry a significant load for years into the future. Once I get the techniques necessary for gear cutting down pat I will consider shelling out $100.00 for a properly ground gear cutter, or $800.00 plus for a full set. The 72 DP size is the one that is used by NorthWest Short Line for their H.O. gears. That's what I would be most likely to get. Regards, Tom Bank ------- Re: Mounting Sherline Rotary Table in Vertical Position Posted by: "Marcus" implmexx~xxaxionet.com Date: Thu Feb 22, 2007 8:46 am ((PST)) Hi Tom: Have a look in the "files" section using this link: http://tech.groups.yahoo.com/group/sherline/files/ Look for "Making (faking) gear cutters" and "Making gear cutters part 2" In it, I describe how to make your own cutters, adapted from the protocol of Ivan Law who wrote a book about it that's a very worthwhile read. The method is very simple and very effective...it enables you to make very good cutters without spending the farm for tooling. Check it out and contact me back if anything is unclear. Cheers Marcus ------- NOTE TO FILE: Marcus discussed gear making techniques at length in earlier conversations above, as did other members of the group. Skimming through the whole file here will help anyone get a better idea of the various ways gears can be made or repaired. I believe Marcus' earliest elaboration of this method was in Oct 2002. You should read his original comments here as well as his files posted in the Sherline group, where there is a polished summary version of the instructions along with some truly excellent illustrations. Pictures there really helped me to understand this method. (Marcus, thanks.) ------- Re: form tool grinding attachment [sherline] Posted by: "David Robertson" davidr415x~xxyahoo.com Date: Mon Mar 12, 2007 6:13 pm ((PDT)) > anyone know of plans for a form tool grinding attachment for making > gear cutters? thanks Barry Barry, Lindsay publishing has a booklet by Robert Porter that has what you want. See it at: http://www.lindsaybks.com/bks4/porter/index.html David ------- Re: form tool grinding attachment Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Mon Mar 12, 2007 6:54 pm ((PDT)) Hello Barry: Not sure if this is exactly what you're after, but take a look in the files section under: making (faking) gear cutters and making gear cutters part 2 DC ------- Re: form tool grinding attachment Posted by: "Marcus" implmexx~xxaxionet.com Date: Mon Mar 12, 2007 7:32 pm ((PDT)) Hi Barry: Were you hoping to use a Sherline machine as your grinding machine? If so, you have two big issues to overcome. First, the Sherline will be destroyed very quickly if you don't guard it meticulously from the grinding grit that's generated when you form dress the wheel. Second, a successful involute form dresser will require some pretty complex and precise parts, whereas a "fake" involute form dresser will generate an arc, which rapidly gets quite large as the tooth count on the gear increases or as the DP gets coarser. The most common proper way to do this on a "real" grinder is to use a gadget called Diaform dresser, which uses a 10X full size template and follows it with a diamond on a pantograph. The template is CNC machined to shape, and mounted on the Diaform table. My Diaform is HUGE...it's bigger than a whole Sherline mill, so you have little chance of making or adapting something that works on this principle without a big and sophisticated engineering effort. The "fake it" method does have some promise however if you can protect the machine well. You need to use your rotary table as the platform for your dresser, and rig an arm on which you can mount your diamond and position it accurately to dress a convex radius of the correct size on the wheel. Then you neeed to be able to position the axis of the rotary table precisely with respect to the periphery of the wheel. The dressing takes place with small successive cuts of about 0.001" at a time, until one side of the wheel is properly shaped. The cutting tool blank is then positioned correctly relative to the wheel and the whole width of the flank is formed to match the wheel. The blank is flipped 180 degrees and the second flank is ground. An alternative approach is to dress a smaller convex radius on the periphery of the wheel so that in cross section, the wheel has a complete half round shape on its periphery. The blank is then positioned on a swinging arm (the rotary table?) such that the swing arm axis sits in the correct position to shape the flank of the cutter. The correct profile of one flank is then generated by swinging the blank past the convex edge of the wheel. The first approach is the better of the two, because the setup is much easier to get accurate; in fact, you are almost guaranteed to fail using the second method, just because it's so difficult to get everything exactly into position and keep it there while swinging the cutter blank on its arc. If you really think about it, a session with a fine dental diamond in a Dremel, manipulated freehand or mounted upside down on a little tilt table, and using an existing gear as a template and a good strong light to hold the pair up to while judging where to nip a little more, will probably get you further, faster than the setups I described earlier. It does not do repetition well, but for a one-off, it will serve amazingly well, and it's very simple to set up. As far as your original question, I'm not aware of any plans available to make any of the gadgets I described. I think you'll likely have to cobble up your own design. Cheers Marcus ------- Re: Newb saying hi and a couple questions [atlas_craftsman] Posted by: "Rexarino" rexarinox~xxgmail.com Date: Mon Apr 16, 2007 2:06 pm ((PDT)) On 4/16/07, n5kzw wrote: > Pat, when you set up your change gears, put a piece of heavy printer > paper or a piece of a brown grocery sack between the gears to set the > proper spacing. Then, use a good dry lubricant from the bicycle shop. > Regards, Ed As Ed posted, Atlas suggests the same. Here is a quote from page 127 of THE MANUAL OF LATHE OPERATION AND MACHINISTS TABLES, Atlas Press Company, Twenty Fourth Edition, "A method often used to obtain proper gear clearance is: (1)Place a sheet of thick writing paper between the teeth of the two meshing gears, (2) tighten gears in position, (3) remove paper. A small amount ofgrease, preferably graphite grease, applied to gear teeth will often aid in obtaining smoother, more quiet operation." I use Lucas Heavy Duty Oil Stabilizier (NAPA auto parts) on my gears - they are less than half as noisy as they were with graphite, and the stuff stays on the gears well. No affiliation with NAPA or Lucas. rexarino ------- Re: Newb saying hi and a couple questions Posted by: "Brett Jones" brettx~xx5foot2.com Date: Mon Apr 16, 2007 2:22 pm ((PDT)) Cool. I'm going to try this technique. The bar chain oil I'm using works well enough, but it does make a bit of a mess. The Lucas product sounds like it's worth trying also. Brett Jones ------- Re: Newb saying hi and a couple questions Posted by: "Rexarino" rexarinox~xxgmail.com Date: Mon Apr 16, 2007 3:04 pm ((PDT)) Brett, I've been surprised at how much of the Lucas product stayed on the gears. I've had a "trail" of flung-off lube on the backgear cover from every other product I've tried. The lucas product hasn't left nearly as much of a trail, perhaps none, since I didn't completely clean the cover or all the gears before applying it. I did notice that the gears with heavy doses of previous lube are still ejecting stuff, but on the gears I 'sorta cleaned' the Lucas goo is staying in place nicely. It's a good deal stickier than bar chain lube - I don't think the wood chips would ever fall off if you put this on a chain saw bar ;/) The only question is, Is it too sticky? Don't know... rexarino ------- Re: New photos [sherline] Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Sun Sep 16, 2007 10:15 am ((PDT)) Martin Dobbins wrote: > That's a very nice looking set of gears. Did you spoke them by > milling or the traditional way? Thanks very much. They were spoked by milling, full CNC on a rotary table. With a high-helix, carbide, micro-grain end mill; takes one roughing pass, plunging through at an angle, followed by a finish cut at reduced tool offset. Less than a minute per spoke. One of these days I'm going to post a paper in the files area detailing my procedure. Very briefly it's: Layout and rough cut the blank on a band saw. Drill and ream 3/8" center hole. Install on fixture centered in 4 jaw chuck. Turn and face the blank. Transfer chuck with fixture and blank to RT on angle plate on mill. Cut the teeth. Change RT to vertical and mill the spokes. Transfer the chuck back to the lathe. Lathe file to de-burr and bevel the teeth (good eye, Jerry G.) I've got this down to where I can knock out a finished gear in a couple of hours. In the past, I've lapped and polished gear faces to a mirror finish. Recently I got some ceramic media for my vibratory tumbler, and this set was finished that way. I think I like the matte finish. DC ------- Taig Lathe and Clock Building [taigtools] Posted by: "bob_ledoux" bobledouxx~xxproaxis.com Date: Tue Dec 11, 2007 6:18 am ((PST)) Here is an interesting discussion concerning a fellow choosing a lathe for clock building. The Taig is featured. http://www.nawcc-mb.com/bbv2/bbBoard.cgi?a=viewthread;fid=14;gtid=263132 ------- NOTE TO FILE: Thanks to Bob, I got to see a very thoughtful discussion about the pros and cons of various small lathes, along with some smart custom setups for cutting gears that would be useful in general, not just for clocks. And not just for Taig lathes. ------- Re: Wheel cuttng [taigtools] Posted by: "kd006" kd006x~xxyahoo.com Date: Wed May 7, 2008 5:09 pm ((PDT)) "Terry Hart"wrote: > Hi all, > I have retired early through ill health and had started renovating > clocks as a hobby, this led on to buying my taig lathe about 18 > months ago. I haven't used a lathe since I was a schoolboy nearly 50 > years ago and consequently I can remember nothing that was taught me. > I have purchased the cdroms JFR videos and found them very helpful, I > also have the Tony Jeffree book which is excellent but difficult for > me to follow. > I am moving away from clock renovation as I would really like to > build something from scratch. I plan to make scale models of various > types of clock escapements, Model steam and Stirling hot air engines > and eventually a clockwork powered Orrery (model of the solar > system). I have the basic taig setup plus the milling head and know > that I need to use the Taig to cut wheels for the gearing. I have > looked at many differnt plans etc and cant make much sense of them. > Is there any one dividing system that is both simple to make and can > offer the capacity to make wheels of a wide range of sizes including > quite large ones. Equally if someone out there has a setup they want to > sell I would be interested. Thanks Terry Hart Plymouth Devon England Terry: Have you logged in on the British Horological Society or NAWCC websites? They are probably more knowlageable about gear hobbing. I would think you would need a hobbing cutter mounted in the headstock and a indexing head or rotary table mounted on the crossslide perpendicular to the cutter. Depending on the number of teeth you could probably cobble up a few disks with index holes and build you own jigs but if your after more than a few pitches and tooth counts I would suggest a rotary table or index head for flexibility. Might even want to look at I think it's called Division Master a stand alone driver for a rotary table for such things. Let us know what you find, sounds like some nice projects you have in the works. Kristin ------- Re: Wheel cutting Posted by: "Blair Shallard" bshallardx~xxmac.com Date: Wed May 7, 2008 5:46 pm ((PDT)) Hi Terry. Two things: One. Join the minilathe horology group on Yahoo for lots of interested advisors, and... Two. Buy Malcolm J Wild's book on gear cutting in horology which will answer most of your questions anyway. It should be available by mail order from Meadows and Passmore. http://groups.yahoo.com/group/mlhorology/ http://www.m-p.co.uk/ Regards, Blair. ------- Re: Wheel cutting Posted by: "kd006" kd006x~xxyahoo.com Date: Wed May 7, 2008 6:53 pm ((PDT)) Blair: Thanks for the link to that group, doub't I'll do much with it but it looks like a good resource. I've got one 1867-68 Seth Thomas and another 20th century clock movement waiting for a case but am always interested in lurking and learning. It may prove usefull someday. Kristin ------- Re: Wheel cuttng Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Thu May 8, 2008 1:13 am ((PDT)) Terry - A few years back I built a "wheel cutting engine" using Taig lathe parts and also my dividing head built from a Taig headstock (the one I described in my book). I wrote it up for Model Engineers' Workshop magazine at the time (issue 96, feb/march 2004)- which reminds me, I should put that article on my website sometime. The main reason I built it was to demonstrate its use with my Divisionmaster controller (see www.divisionmaster.com), using a stepper motor to drive the dividing head instead of the more conventional division plates and indexing arm; however, the same result could be achieved with a manually operated dividing head. The basic idea is that you mount the dividing head on the Taig milling attachment, which is in turn mounted on the lathe cross- slide. The dividing head is oriented so that its spindle runs parallel to the lathe bed; however, the "twist" is that you take the lathe headstock off the bed and mount it rotated through 90 degrees so that a gear cutter mounted in the spindle can cut teeth in the blank. This is a bit difficult to visualize without seeing the pics, so I have put some pics on the website that may help you "get the picture" as it were - see: http://ph.groups.yahoo.com/group/taigtools/photos/browse/1e82?c= If the link doesn't work, go to the files section of the group site http://ph.groups.yahoo.com/group/taigtools/photos and look for a subdirectory called "Tony's wheel cutting engine". The vertical movement of the milling slide gives you adjustment for depth of cut; the cross slide movement allows you to center the blank above the plane of the cutter, and the saddle traverse allows you to pass the blank across the rotating cutter to cut the teeth. You will spot from the photos that I used a non-standard lathe bed -- Taig make an aluminium extrusion that is the same profile as the bed, and I used some of that mounted on a steel box section base (Peter Morrison at Peatol in the UK supplied the extrusion to me). However, using the standard lathe bed would produce a stiffer setup. This "engine" is good for cutting clock wheels, but I haven't tried cutting pinions on it yet so I don't yet know whether the setup will be stiff enough for that kind of use. The alternative (and more conventional) approach would be to hold the blank in the lathe spindle and use some kind of indexing attachment on the lathe headstock - some use direct indexing via a plate attached to the spindle pulley, or you could attach the dividing head bits from my design directly onto the lathe headstock. You then need to hold a separate milling spindle on the cross slide/vertical slide to pass the cutter across the blank. I hope that helps... Regards, Tony ------- Re: Wheel cuttng Posted by: "bob_ledoux" bobledouxx~xxproaxis.com Date: Thu May 8, 2008 6:39 am ((PDT)) Wheels and pinions can be made without a mill. The basic decision is whether the lathe head is used as a dividing head or cutting driving arbor. I prefer to use the lathe as the dividing head. An index plate with 60 and 64 holes will give all the divisions needed for a clock. Use 8 teeth for the pinions and 32/8 and 10/30 teeth combo for the motion works. Consider lantern pinions. John Shadle shows a simple drilling rig that fits on the cross slide: http://onlineclockbuilding.com/ A simple "C" frame can be built to fit on the cross slide. It drives a flycutter to cut the wheel teeth. J Malcolm Wild describes this in his book "Wheel and Pinion Cutting in Horology." ------- Re: Wheel cuttng Posted by: "Clif Lowry" CLOWRYx~xxSATX.RR.COM Date: Thu May 8, 2008 1:08 pm ((PDT)) Terry: A pretty simple solution is a dividing disk outboard of the headstock and a cutting frame in the milling attachment. With risers you can easily cut some pretty large gears. If you intend to cut more than a few gears, it would probably be worth your while to build a wheel cutting engine. An excellent straight forward plan is provided by your countryman, G.E. Lloyd-Jones. Visit the BHI website to find the article. Good luck, Clif Lowry San Antonio ------- Re: Wheel cuttng Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Thu May 8, 2008 5:01 pm ((PDT)) Terry: I would have to respectfully disagree with use of a lathe to cut horological wheels and gears of any type. These arrangements become overly complicated in a hurry. They are seldom as rigid as desirable for this type work. Because of these and other issues it requires a skilled peron to do accurate work and recognize problems before they damage a work piece. When considering the projects you have suggested you wish to do, you're definitely going to need a small quality milling machine with a compatible rotary table. With this equipment wheel and pinion cutting is very simple and straight forward with very simple set ups requiring little skill. In addition the Small Mill will allow you to accurately machine your own wheel cutters that can then be hardened. This of course will save as much as $125.00 per cutter. In addition to having the ability to machine any part in a movement the properly selected mill will also replace other expensive equipment. This includes a sensitive Drill, Bushing machine and can also be used as a highly accurate depthing tool. However the most important thing is, that the capabilities of a quality small mill will allow you to develope the skills needed to do the projects you wish to do. Jerry Kieffer ------- Website update [was Re: Wheel cutting] [taigtools] Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Mon May 19, 2008 3:43 pm ((PDT)) I've added a couple of articles to my website here: http://www.jeffree.co.uk/modelengineering.html One describes the "wheel cutting engine" I mentioned in a post a couple of weeks ago; the other describes a method for cutting involute gears using home-made cutters. Regards, Tony ------- Re: sherline manual rotary table [taigtools] Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Fri May 23, 2008 10:34 am ((PDT)) "leeharrysouth" wrote: > But what of this matter of interpolating manual table positions when > dealing with fractions less than one tenth of a degree. Can this > result in match up problems when cutting a gear with an odd number of > teeth to mate with an existing gear? Keep in mind that I have very > little experiance with gear cutting. Maybe I am looking at this a > little to hard. Thanks Johnny Johnny: As a old German Machinist one told me, you can`t afford perfect. Depending on diameter, one tenth of a degree can be quite accurate. For example for a 1.000 diameter gear, one tenth of a degree would be plus or minus .0008726". Because of the clear markings on the handwheel, the space between the 1/10th marks can be easily divided by five under magnification if required to a accuracy of .0001745" in this case. Most teeth sizes on common commercial gears are at least + or - about .002" with additional backlashes of .002" to about .010" or so. To make a long story short, if you are reasonably careful with your handwheel settings you will still be many times more accurate than required for proper fuctioning Gear Trains. Before purchasing my CNC unit I used the Sherline manual Table to cut Watch wheels and for Model Engineering projects that were half the size of Watch wheels. Other than from my own mistakes, the table produced wheel and gear trains smaller and far more accurate than could be purchased or required. I started using the manual Sherline Table when I discovered that it was more accurate for small work than my watchmakers index plates. However for Wheel/Gear cutting the CNC system is the only way to go. Jerry Kieffer ------- Re: Will Myford Gears fit the 10F [atlas_craftsman] Posted by: "anthrhodesx~xxaol.com" anthrhodesx~xxaol.com Date: Mon Jun 30, 2008 11:10 pm ((PDT)) In a message dated Sun Jun 29, jmileman writes: > Picked my 10F up yesterday and although I've got a load of tooling and parts with it there are some gears missing. Being in the UK, Atlas parts are a bit thin on the ground but there is plenty of Myford stuff. Does anyone know if Myford gears will fit/work on the 10F lathe? < Jim: That's an interesting question. There are two issues, DP of the gears and the bore and keyways of the gears. The simple answer is you can't mix the 20 DP Myfords with the 16 DP Atlas gears where the drive is through the gear teeth. The part of the drive which creates the biggest problem is the spindle gear and the gears on the tumbler reverse mechanism. If you could replace all of these with 20 DP gears, the rest of the drive would pretty much be a straight swap. Alternatively, if you were to keep the 32 tooth gear on the tumbler reverse and all the gears above it but alter the 32 / 16 stud so that the 16 could be replaced by any 20 DP gear, then all gears from the stud down could be Myfords. Finally, you can mix different DPs in a gear train as long as the drive doesn't require meshing the teeth of different DPs. So you could have the original Atlas 32 on the tumbler drive an Atlas 48 on the compound bushing, then put a Myford 60 on the compound bushing driving a Myford 80 on the leadscrew. With an 8 TPI leadscrew this would cut a 16 TPI thread. (This isn't a particularly useful setup, there are better ways to do it; it merely illustrates the method by which incompatible gears can still be assembled into useful gear trains.) Anthony Berkeley, Calif. ------- Re: Gear Cutting [sherline] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Wed Jul 2, 2008 12:16 pm ((PDT)) "lewis40207" kendricklewisx~xxinsightbb.com wrote: > Hello -- I'm new to this group and have a "dumb question". How do I > merge my 5400 Mill and my 4400 Lathe together in order to be able to > cut clock gears. I have a Chronos Wheel Engine and a Chronos Pinion > Mill, but want to be able to cut gears on my Sherline equipment. I > have a set of division plates for the Sherline. Thanks in advance for > any help you can provide. Kendrick I've just posted a file on gear cutting. This is a rough draft of a photo illustrated tutorial I was working on some time ago and got distracted from. Will take it up again as time permits. This week I'm working on the largest gears I've done on a Sherline. Will post some more photos as work progresses. see: http://tech.groups.yahoo.com/group/sherline/files/D.C.Clark/Ge ar%20Cutting/ Comments, suggestions, questions, welcome as always. Keep in mind it's just a first draft. Much more detail could be included. It would be nice to get some feedback from members on what they'd like to see covered. DC ------- Re: Gear Cutting Posted by: "Blair Shallard" bshallardx~xxmac.com Date: Wed Jul 2, 2008 3:27 pm ((PDT)) Hi Kendrick: Mr. Kieffer has just posted some photos and an explanation of gear cutting on his Sherline equipment that you may find very helpful on the minilathe horology group. I also have some photos up which might be somewhat less helpful, but still of interest. I recommend you join this group too, as there are a number of people there who will be able to help you out with clock specific questions, and gear cutting is a topic that has just been covered. http://groups.yahoo.com/group/mlhorology/ Regards, Blair ------- Re: Gear Cutting Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Wed Jul 2, 2008 4:57 pm ((PDT)) > Jerry G, Thanks for your response -- how do I get in touch with Jerry > Kieffer? Take care, Kendrick Kendrick: Actually it's quite easy. In fact some of the neighbors just ring the door bell and walk in. However unlike my Buddy Mr. Glickstein I still find the need to work in the shop during the day. He also forgot to mention how blunt and to the point I am. I hope you don`t mind. Personally I am not a big fan of Index plates especially the way they are set up as typically published in the Horological Community. I suspect that if those suggesting some of these setups had to demonstrate Quality work they would find themselves in deep trouble. With my Index plates as with Wheel/pinion cutters I never seemed to have had the right ones. And when I did it was always the row that had the defective hole someplace. Again Personally I prefer the Rotary Table on the Mill arrangement as suggested/shown by DC. I find this to be more versatile, accurate and efficient. One of the critical things when cutting teeth is to have a clear and visible view of the cutting process for setting accurate tooth depth and monitoring the cutting process. I will post a couple of photos of such arrangements under my Name. Having said that, if you wish to use your dividing plates with your Sherline equipment it is really quite simple since you have both a lathe and mill. Assuming the dividing plates are accurate and have the correct count they can be used. I will also assume they were designed to be mounted on your Lathe headstock and you have the ability to properly/ accurately mount them. (Including the index locking system.) If so I would proceed as follows. Next I would use an existing or purchase a Sherline Headstock spacer block. I would then drill and countersink four holes in the block that would allow you to mount it to the Mill bed with tee nuts. Once completed this will allow you to accurately machine a Arbor on the lathe and then transfer the lathe headstock/mounted index plate to the mill mounted to the spacer block. This assures accuracy as also suggested by DC when the arbor is not removed from the chuck. You can follow any one of several arrangements on the Mill for cutting teeth as suggested/pictured in the Sherline instruction sheets and catalogs. Jerry Kieffer ------- Re: Gear Cutting Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Wed Jul 2, 2008 6:50 pm ((PDT)) > This week I'm working on the largest gears I've done on a Sherline. > Will post some more photos as work progresses. D.C. Clark Just finished cutting the teeth an hour ago. This is a 60 tooth, 12 pitch, involute gear, pitch diameter of 5", cut with a commercial tool. It's 2 blanks of 1/4" 7075AL being machined together. Since this is too big for a Sherline chuck, I've made a faceplate for the lathe out of 1/2" MIC6 tooling plate and bolted the blanks to it. A headstock riser block is also used. A handy thing about the Sherline headstock is that a milling collet can be mounted at the same time as the faceplate. A 1/4" gauge pin in the collet centers the blanks. The mounting holes in the gear blanks will be consumed by cutting the spokes. The setup for the mill is one that I've posted a photo of at: http://tech.ph.groups.yahoo.com/group/sherline/photos/view/d71e?b=8 New photos of this job begin with: http://tech.ph.groups.yahoo.com/group/sherline/photos/view/d71e?b=17 A substantially larger gear could be cut with this arrangement by blocking up the Rotary Table. Rigidity gets to be an issue, though. Sharp tools and light cuts help. Kendrick, you didn't mention what sort of gears you wanted to make. Though some of the basic principals are the same, there's a world of difference between making gears this size and making a pinion for a wristwatch. You can do either on a Sherline, but the setup's a little different. As always, the more information you give us, the more help you'll get. Hope you found some of this interesting, at least. best regards, DC ------- Re: gear cutting Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Mon Jul 14, 2008 5:57 pm ((PDT)) "blwolfsberg" wrote: > does anyone have plans to convert Bob Porter's gear cutting > attachments to the sherline. I'm looking to make my own gear cutters. > thanks barry Barry: Jeweler's Lathe Attachments such as Milling spindles and Index units can easily be mounted on a Sherline Lathe. Since most jeweler's lathes have a slightly greater swing than a Sherline, an adapter plate can be made for the bed that will accept all attachments from a particular manufacturer or brand of lathe without modification. (In most cases) I would need to see photos of the attachments to suggest a particular design. Better yet if you have the attachments, it would be a good exercise to design your own. However having used Horological jeweler's lathe attachments in the past I would like to comment. They are truly a sight to behold when set up, both in complication and creative design. The jeweler's lathe has traditionally been used by an individual repair person to assist in the fitting and repair of parts. It was designed for and best suited when used with a Graver. Cross slides, milling spindles and index attachments etc. were an afterthought that came along over the years. In use the first thing you find is that they are very time consuming to set up. In addition you also quickly find that they are just not very practical or efficient or even accurate unless used in the hands of a highly skilled person with many many years experience. Especially when compared to Sherline equipment when used as it was designed to be used or similar to how both Watches and clocks were manufactured. Standard machining setups will produce watch parts more accurately and efficiently than any of the several watchmakers setups that I own. When producing cutters and cutting teeth on both watch wheels and pinions I only use the Sherline Mill, Vise and a Rotary table for indexing. Setups are similar to suggested setups covered in the Sherline instruction sheets and as discussed on this board. You can also search this site under "gear cutting" for a great wealth of information. Jerry Kieffer ------- Making multi-point gear cutters [taigtools] Posted by: "Dean Williams" deanofidx~xxyahoo.com Date: Fri Aug 29, 2008 4:06 pm ((PDT)) I made up a jig for cutting multi-point gear cutters not long ago. Something I saw on the horology group and it turns out to be a pretty handy way of making these cutters. With Thornton gear cutters going for near $100 each (!) it's a lot cheaper, too. Anyway, I put up a page showing the setups on the Taig lathe and have included quite a few pictures and some notes that may be of interest. Check out the address below, if you like. http://tinyurl.com/Multipoint-cutters Dean ------- Re: Making multi-point gear cutters Posted by: "Nicholas Carter and Felice Luftschein" felicex~xxcasco.net Date: Fri Aug 29, 2008 4:23 pm ((PDT)) You always manage to do beautiful and interesting work Dean! See our homepage at www.cartertools.com/nfhome.html ------- Re: Making multi-point gear cutters Posted by: "David Robertson" davidr415x~xxgmail.com Date: Fri Aug 29, 2008 4:31 pm ((PDT)) Just FYI and to make sure credit is given where credit is due... the article that describes this technique is written by Dave Creed a fine clockmaker and tool maker in the UK (for Clocks magazine). A very similar method is also described by J Malcolm Wild in one of his books. Dean... great job of showing the method and documenting it. David Allison has also had good luck with these cutters following this method... as have I. David Robertson ------- Re: Making multi-point gear cutters Posted by: "Dean Williams" deanofidx~xxyahoo.com Date: Fri Aug 29, 2008 8:29 pm ((PDT)) Just for anyone who happens to read this thread, and has not had a look at my webpage, I made it clear in the opening paragraphs that I take no credit for the design or method. Like a lot of things on the web, it's hard to know who "thunk it up" first. That said, I'm quite happy for people like Mr. Wild and Mr. Creed for sharing so many of their very useful ideas and techniques. David and Nick, thanks for having a look. Dean ------- Re: Making multi-point gear cutters Posted by: "David Robertson" davidr415x~xxgmail.com Date: Sat Aug 30, 2008 6:26 am ((PDT)) That you did, Dean... very clearly. I was not implying otherwise, just naming names in case anyone was interested or knew the gentlemen mentioned. You did a great job of implementing and improving upon their ideas and did a GREAT job of photo-documenting the process. I certainly hope my note did not come across as other than complimentary to you. David ------- Re: Making multi-point gear cutters Posted by: "Dean Williams" deanofidx~xxyahoo.com Date: Sat Aug 30, 2008 3:07 pm ((PDT)) Not at all, David, and not that I'm looking for compliments. This seems a very good way of doing things, and I thought Taig owners would like to see it done on the Taig lathe. By the way, David Creed contacted me about authorship of the original write-up and I've edited my web page to reflect that. Dean ------- Re: Making multi-point gear cutters Posted by: "klickcue" klickcuex~xxyahoo.com Date: Sat Aug 30, 2008 9:12 am ((PDT)) That is so neat. Though I will never make one, it was great that you shared your technique with nice pictures. Thanks, Chris ------- Re: Making multi-point gear cutters Posted by: "Michael Fagan" woodworker88x~xxgmail.com Date: Sat Aug 30, 2008 2:40 pm ((PDT)) Awesome work. This answers the two issues I had with making my own multi-tooth gear cutters, namely how to relieve the cutter so it doesn't rub (by turning"facets" on the blank) and how to repeatedly index the cutter throughout the cutting and sharpening process. This method could also be used to make other sorts of circular form tools in addition to gear cutters. ------- Gear Cutting [LittleEngines] Posted by: "Gary Briggs" briggs451x~xxyahoo.com Date: Thu Oct 2, 2008 2:30 am ((PDT)) Old topic, but new to me. Can someone refer me to a pretty basic illustrated tutorial on cutting simple gears? I have the Micro-Mark vertical mill and indexing table. ------- Re: Gear Cutting Posted by: "Ray and Ruby Brandes" rvbx~xxray-vin.com Date: Thu Oct 2, 2008 5:27 am ((PDT)) Gary: Search on "involute gear". You can make sloppy gears that work, but are noisy and inefficient. For the best gears you need to cut the involute profile. If you go this route you can buy cutters for larger teeth, but for miniature gears you will need to grind a tool. Regards, Ray in FLA ------- Re: Gear Cutting Posted by: "Marty Shouse" shouseblx~xxyahoo.com Date: Thu Oct 2, 2008 6:27 am ((PDT)) if you guys need gears let me know i have an EDM and i cut any gear you need. Marty ------- Re: Gear Cutting Posted by: "lori.castro" lourivalcx~xxgmail.com Date: Thu Oct 2, 2008 6:27 am ((PDT)) Maybe this will help you: http://www.aardvark.co.nz/pjet/gears.shtml Another link: http://helicron.net/workshop/gearcutting/ ------- NOTE TO FILE: The Helicron Workshop site has some useful links to other sites with gear cutting information. ------- Re: Gear Cutting Posted by: "Jim E." jim0000x~xxattglobal.net Date: Thu Oct 2, 2008 1:20 pm ((PDT)) Rent this video: http://smartflix.com/store/video/77/Making-Gears-the-Easy-Way Graciously, Jim E. Lakewood, CA ------- Grinding gear cutters [LittleEngines] Posted by: "Tom Faragher" tfaragherx~xxverizon.net Date: Thu Oct 2, 2008 5:52 pm ((PDT)) Single point fly cutter bits for cutting small gear teeth can be made from 1/8 inch square high speed steel tool bits. The process involves using a grinding table on a small lathe with a thin grinding wheel mounted on an arbor in the spindle. The grinding table should be set ABOVE the center of the grinding wheel to get the appropriate end relief on the finished cutter. Side relief is achieved by grinding the tool bit at an angle. A sample gear of the same pitch and close to the same tooth count as the gear to be cut is required to copy the cutter profile. Start out by removing the majority of the material with a bench grinder and then finish up with the thin wheel. I use Dremel cutoff wheels running at high speed in the spindle of a watchmakers lathe. Frequent testing of the profile against the sample gear is required. I can usually grind a cutter in about 20 minutes. I have added a photo album to the Little Engines group titled "Gear Cutting". Tom Faragher ------- Re: Grinding gear cutters Posted by: "Ray and Ruby Brandes" rvbx~xxray-vin.com Date: Fri Oct 3, 2008 3:15 am ((PDT)) Tom: Good method for making the cutter! Sometimes simple is better. Using an existing gear for a template is something I had not thought of. Regards, Ray in FLA ------- Re: Grinding gear cutters Posted by: "corey renner" vandal968x~xxgmail.com Date: Fri Oct 3, 2008 4:03 pm ((PDT)) For those that don't feel like poking around in photos for 10 minutes looking for the pics, they are located here: http://ph.groups.yahoo.com/group/LittleEngines/photos/browse/7610 cheers, c ------- Gear cutting (was lathe base discussion) [sherline] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Tue Oct 14, 2008 6:17 am ((PDT)) For Greg Procter et al, I've started a new thread since your gear cutting inquiry is still under the previous topic. This makes it easier for members to search the archives. Some time ago I wrote a paper on cutting gears with a rack shaped cutter by translating the cutter to simulate a rack. I've posted it at: http://tech.groups.yahoo.com/group/sherline/files/D.C.Clark/Gear%20Cutting/ David Clark in Southern Maryland, USA ------- Re: small steel worm [taigtools] Posted by: "Pierre Coueffin" pcoueffinx~xxgmail.com Date: Sat Nov 8, 2008 5:27 pm ((PST)) On Wed, Nov 5, 2008, alex campbell wrote: > hi all, i would like to make a small steel worm and brass worm wheel.. > the worm would be about 1 1/2" L x 3/16"[1/4"]D with pinions turned > down to about .5mm [1mm max]..the pinions would rest in brass bushings. > the brass worm wheel would be about 1/2"Diam.. 1/8"thick and have > 30 teeth. any help ..advice on how to do this on the Taig would be > appreciated. thanks in advance. Jim Sapp describes the process of hobbing a wheel using a standard tap better than I could hope to. You could then use standard all-thread or a section of a bolt for the worm. http://www.atmsite.org/contrib/JSAPP/wormgear/wormgear.html ------- Making worm gears... Posted by: "mbonfire2002" mbonfirex~xxhotmail.com Date: Sat Nov 8, 2008 5:50 pm ((PST)) You might find interesting my attempt at making a worm gear on the Taig. I used it to make a stepper driven rotary drive for my mill (works great for my needs). http://webpages.charter.net/mbonfire/wormgear.htm Steve ------- Re: Gears [Min_Int_Comb_Eng] Posted by: "ray" raym321x~xxyahoo.com Date: Wed Nov 19, 2008 8:06 pm ((PST)) I talked to Ron at American Precision and he was kind enough to send me this---- >> For small quantities of standard gears, catalog component dealers are your best choice. Try selecting a gear online at a site like W.M. Berg's, http://www.wmberg.com/; Martin Sprocket, http://www.martinsprocket..com/home.htm; Boston Gear, http://www.bostongear.com/; Rush Gears, http://www.rushgears.com/: PIC Design, http://www.pic-design.com/; Linn Gear Co., http://www.linngear.com/, KHK Stock Gears, http://www.khkgears.co.jp/en/, or Stock Drive Products, http://www.sdp-si.com/ Stock Gears, Inc, www.stockgearsinc.com specializes in plastic gears. Custom gears, such as the ones we make, will cost nearly $1000US for each small lot. If you cannot use an off-the-self product, please send us a sketch or drawing; I will be happy to give you a price. Our web site can assist you in gear design. Thank you for asking American Precision Gear to quote. Dan Sungail American Precision Gear 1029 American St. San Carlos, CA 94070 Ph 650 595-3664 Fx 650 595-0388 << hope it helps you too. Ray M ------- Clock Wheel and Pinion Cutters [MyMyford] Posted by: "timperrin97" bobwozere12345x~xxaol.com Date: Tue Jan 6, 2009 12:10 pm ((PST)) Although this is probably not the best place to ask about clockmaking I thought it was a good place to start. Does anyone know of a reasonably good way of making a clock wheel and a clock pinion cutter? It doesn't need to be perfect but I would rather not have to fork out Ł120 for 2 gear cutters. Many Thanks Tim ------- Re: Clock Wheel and Pinion Cutters Posted by: "Tim Ostley" Tim.Ostleyx~xxgooglemail.com Date: Tue Jan 6, 2009 1:29 pm ((PST)) Dear Tim, You can use a fly cutter to cut clock wheels - I have done so with escape wheels in the past. You do, however need to be able to accurately grind the profile of the cutter. Have a look at some of the John Wilding articles in older ME's especially the beginners clocks. You can also make a single tooth circular cutter. Hope this helps. Tim (another one!) ------- Re: Clock Wheel and Pinion Cutters Posted by: "G Bennett" gbennettx~xxshaw.ca Date: Tue Jan 6, 2009 11:11 pm ((PST)) This is the reference that came to mind and its basis. I have no personal experience. See MEW # 125, May 2007 for Bill Morris' horology article "Making Cycloidal Pinion Cutters". His article says that he draws heavily from W.O. Davis's 'little classic' "Gears for Small Mechanisms". Cheers, Graham ------- Re: Clock Wheel and Pinion Cutters Posted by: "mike.crossfield" mike.crossfieldx~xxvirgin.net Date: Wed Jan 7, 2009 2:08 am ((PST)) The MEW article that Graham refers to is good. I have made similar single tooth pinion cutters in the past, and these have worked well. The only drawback is you need to cut slowly, and take several shallow cuts, with plenty of cutting oil. Still, they cost very little compared to Thornton-type cutters. Simple fly cutters are fine for brass wheels. Mike ------- Re: Clock Wheel and Pinion Cutters Posted by: "S or J" jstudiox~xxtbaytel.net Date: Wed Jan 7, 2009 5:50 am ((PST)) Hi Tim. The problem has been resolved by many on the web without the cost of commercial cutters. Here are two very good sites: First from Hugh Sparks: http://www.csparks.com/watchmaking/WheelCutting.html and from John Shadle's comprehensive clock making site (the flycutter article): http://onlineclockbuilding.com/DOWNLOADS/download.html HTH Steve -- in Thunder Bay, Ontario, Canada Machining and Metalworking at Home http://www.janellestudio.com/metal/ ------- Re: Clock Wheel and Pinion Cutters Posted by: "youra_windsor" yourax~xxgloubiboulga.org Date: Wed Jan 7, 2009 6:02 am ((PST)) Hi Tim. If you wander over the the MLHorology Yahoo group, you'll find an excellent article in the files section on exactly this subject by David Creed - not made any myself using this method as yet, but intend to, for exactly the same cost reasons you mention! Some of the MLHorology group members have reported excellent results using this method. Link: http://groups.yahoo.com/group/mlhorology/files/Wheel%20and%20Pin ion%20Cutter%20Making/ There is also an article about flycutter making at: http://onlineclockbuilding.com/DOWNLOADS/download.html Finally, there are some cutters available from: http://www.timekeepersworkbench.com/cutters/index.htm which appear to have a good reputation, and are much cheaper than the Thorntons approach. HTH, Youra ------- Re: Clock Wheel and Pinion Cutters Posted by: "Collins, Graham" collingx~xxnavcanada.ca Date: Thu Jan 8, 2009 4:22 am ((PST)) I have that issue of MEW, just had it out last night in fact for review. I have been fussing over CNC'ing my lathe (the big one or perhaps my old Taig) as per Tony Jefferree (sp?) articles in MEW. Belt or gear drive or gears for an indexer of some sort sent me searching Bill Morris' article for review - well written and easy enough to understand that. Cheers, another Graham in Embrun near Ottawa Canada ------- Re: GEAR CUTTERS [LittleEngines] Posted by: "Rupert" rwenig2x~xxxplornet.com Date: Wed Feb 25, 2009 2:49 pm ((PST)) John wrote: > There is a pretty good CD from Smart Flix that you can rent for 9.99 > that explains the terms used in gear making. It also shows how to make > a hob, that replaces those involute cutters. And for those that don't know, Smart Flix will rent videos across the line into Canada too. I haven't rented a video from them yet that I didn't think I got my money's worth from. I haven't found a Canadian movie rental place that carries instructional videos of the same caliber. Rupert Rupert Wenig Camrose, Alberta, Canada. http://users.xplornet.com/~rwenig/Home/ ------- Re: GEAR CUTTERS Posted by: "Rupert" rwenig2x~xxxplornet.com Date: Wed Feb 25, 2009 6:34 pm ((PST)) Ken Strauss wrote: > How do they ship to Canada? What are the "handling charges", duty and > taxes? Hello Ken: There is a good explanation on how it works at There are no customs charges, duty or GST. Unfortunately, we Canucks are stuck with paying the return postage unless we live close enough to the border to return post the video on the US side. I've been more than happy with the metalworking videos I have rented. Rupert ------- Re: GEAR CUTTERS Posted by: "Rupert" rwenig2x~xxxplornet.com Date: Wed Feb 25, 2009 7:55 pm ((PST)) Ken Strauss wrote: > Yes, I read "NOTE: shipments to Canada do not include return postage; > Canadian customers are responsible for affixing all required postage for > return shipment." However, it says nothing about how the item gets here > and if any customs charges apply. If it is shipped via USPS then there > is normally a $5 handling fee by the post office plus GST+PST. Have > you used the service from Canada? Hello Ken, Sorry. I misunderstood. The item comes in via priority international mail. There are no customs charges on orders under #20CAD. I understand the amount before charges are charged has risen to $40 but haven't tested that yet. That means no GST and no post office handling fee for orders under those amounts. I can't speak for PST as I live in Alberta where there is no PST. I usually pay the return postage as priority mail too as I get a tracer number that way. You may get a message from Smart flix asking about the where abouts of the DVD shortly after you get it. I believe this message is a standard message sent out by computer if the disk isn't back by a certain date. I didn't have any problems keeping the disk for the week as I kept them posted as to its whereabouts. Hope that answers your question better. Rupert ------- Gear tables, why the difference. [sherline] Posted by: "Walter" wandrsonx~xxwalteranderson.us Date: Wed Sep 30, 2009 9:43 am ((PDT)) I have been reviewing information from a couple of sources concerning the creation of multipoint gear cutters for involute gears. The sources are the Ivan Law book and an article by D.J. Unwin from the October 1971 issue of Model Engineer. Both sources describe the creation of a form tool using hardened pins to create the cutters. know that several folks on this forum suggest directly creating the fly cutter single point tool instead. I thought these tables would be useful for creating a set of fly cutters for a single diametrical pitch. The articles have tables for a 30 degree pressure angle as well as the more standard 20 degree. The problem is that the 30 degree tables in both sources have identical values, while the 20 degree pressure angles are completely different. Does anyone have any idea as to why this might be and which is correct? Ivan Law, Gears and Gear Cutting, p. 114, Pressure Angle 20 degrees Cutter Gear Center Blank Number Teeth Diameter Distance In Feed Width 1 135-Rack 51.30 49.60 17.79 4 2 55-134 32.15 31.60 11.47 4 3 35-54 15.07 15.52 5.87 4 4 26-34 10.26 11.03 4.27 4 5 21-25 8.55 9.40 3.71 4 6 17-20 7.80 8.70 3.44 4 D.J. Unwin, Making Milling Cutters for cutting gear wheels, p 967, Model Engineer, October 1971 Table 1a, Involute Cutter Proportions, 20 degree pressure angle Cutter Gear Center Blank Number Teeth Diameter Distance In Feed Width 1 135-Rack 46.700 44.800 3.934 4 2 55-134 18.810 19.070 3.415 4 3 35-54 11.970 12.640 3.098 4 4 26-34 8.890 9.750 2.875 4 5 21-25 7.180 8.147 2.710 4 6 17-20 5.810 6.864 2.543 4 7 14-16 4.788 5.905 2.387 4 8 12 & 13 4.100 5.267 2.251 4 ------- Re: Gear tables, why the difference. Posted by: "Martin Dobbins" trainnutzx~xxyahoo.com Date: Wed Sep 30, 2009 10:56 am ((PDT)) Hi Walter, I also have the Ivan Law book and remember finding out from somewhere that it was incorrect (misprints maybe?). I would therefore trust the DJ Unwin information over Law's. More later if I can find it. Martin ------- Re: Gear tables, why the difference. Posted by: "Marcus" marcusx~xximplant-mechanix.com Date: Wed Sep 30, 2009 7:55 pm ((PDT)) Hi Walter: I put a set of instructions into the Sherline forum under the files section that shows you a step by step of how to develop the proper geometry for any gear cutter for any pitch or pressure angle. It's labeled Making (faking) gear cutters and Making gear cutters (part 2). Have a look and go through some of the examples by the two authors to find out which is correct. Cheers Marcus www.implant-mechanix.com ------- Re: Gear tables, why the difference. Posted by: "Walter" wandrsonx~xxwalteranderson.us Date: Thu Oct 1, 2009 5:26 am ((PDT)) Marcus: Thank you. I had found those and they are quite helpful, along with several messages you have created on making gears. In order to calculate the table provided by Law and others, I would need to know which gear is used to develop the shape for a specific B&S cutter number. I have ordered the machinery handbook and hopefully that information will be contained. In searching the web for information on what is wrong with the Ivan Law tables, all I have found is references to some old Model Engineer magazine issues where they posted corrections. The only reference to those corrections I've found indicate they (publisher) felt the problem was in the blank width column and that the other dimensions were correct. I suppose the two tables could be using different gear count tooth shapes as their basis, but that wouldn't explain why their 30 degree pressure angle tables are identical. It may be that the differences between the tables are small enough to not be an issue, but they are vexing... ------- Re: Gear tables, why the difference. Posted by: "Marcus" marcusx~xximplant-mechanix.com Date: Thu Oct 1, 2009 9:39 am ((PDT)) Hi Walter: I remember looking at those Ivan Law tables and commenting to myself about the errors, but I don't remember the precise nature of my criticism...it was all a while ago. However, the beauty of Law's method of approximation, is that you're NOT restricted to the B&S set of gear cutters...the whole idea is that you roll your own for the gear pitch and tooth form you want. The nature of the Law compromise is fundamentally different from that of B&S...Law's cutters are not involutes...they are cheaters in which you approximate the involute form with a segment of a circle so the cutter becomes easy to make. The tooth profile is "too curved" for an involute, and the primary compromise is early loss of engagement as the teeth of two gears mesh and then unmesh while rolling together. B&S by contrast, chooses an involute profile that is correct for the lowest tooth count in a series, and continues to use that profile for an increasing number of teeth until the profile is so inappropriate, that a new profile becomes worth invoking. The teeth are also "too curved" to be correct for all but the lowest tooth count in the series, but they are proper involute profiles, not fakes. The functional outcome is very similar in both circumstances, but Law's method gives you the very large advantage of being able to create gears that can be tailored to a wide variety of circumstances. You can manipulate center distance, pressure angle, ratio, and many other features of a gearset freely, and without drastic compromise to the function by cheating with Law...you do not have the same freedom with B&S. Both are subject to the same principal limitations for speed and load capacity because they're both indexed, milled teeth, BUT with Law's method, especially for low tooth counts, you can tip the balance strongly in your favour by increasing the pressure angle and thereby the root strength of the gear teeth, without influencing the ability of the teeth to roll together properly. All this long winded dissertation as it relates to B&S, points out that the lowest tooth number a B&S cutter is good for, is the most accurate; so if you choose B&S, try to stay at the low end when you choose your tooth counts. Of course, you can't do that so easily when you have specific ratios or tooth counts you must achieve. The other thing to note about B&S: whenever possible use high tooth count gears...for example, the profile differences from 120 to 150 teeth are MUCH less influential than the differences in profile between 12 and 16 teeth. With regard to the errors in the Law tables; I'm sorry, but I can't give you any decent advice other than to suggest that I hate tables in general and always avoid them in favour of developing what I need from first principles if I can. I find too often, that there are errors precisely as you've observed, and it's a pain to scrap parts simply because I relied on an incorrect table. That's it in a nutshell. Cheers Marcus www.implant-mechanix.com ------- New file uploaded to sherline [sherline] Posted by: "sherlinex~xxyahoogroups.com" Date: Wed Sep 30, 2009 9:48 am ((PDT)) Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the sherline group. File : /Tables.xls Uploaded by : wandrson Description : Summary of Involute cutter proportions You can access this file at the URL: http://groups.yahoo.com/group/sherline/files/Tables.xls To learn more about file sharing for your group, please visit: http://help.yahoo.com/l/us/yahoo/groups/original/general.htmlfiles Regards, wandrson ------- gear theory primer [SherlineCNC] Posted by: "steve.buys" sbuysx~xxtelkomsa.net Date: Fri Oct 2, 2009 2:48 am ((PDT)) I found this link to a pdf download which helped me. Maybe other newbies might like to view it: http://www.bostongear.com/PRODUCTS/open/theory.html Steve ------- NOTE TO FILE: 09 Oct 2009. There are a couple of British magazines dedicated to the metalworking hobby. Model Engineer dates back to at least the 1930's and concentrates on how-to articles about making steam engines and clocks and the like. Model Engineers Workshop is more recent and concentrates on home workshop metalworking tools and techniques. Just a couple of months ago the publisher finally joined the computer age and got up a website: http://www.model-engineer.co.uk/?source=23&utm_source=NSL0049&utm_me dium=NSL0049&utm_campaign=NSL0049 Some parts of the website are available to any viewer. Some parts like forums require free registration in order to post messages, but you can read the forums without subscribing. Some site content like the current copy of the news-stand magazines (including all prior copies for 3 years back) requires you to be a paid-up subscriber to the particular magazine. Recently, the Editor added some free (to any site visitor) magazines that are long extinct. Online right now are the first four issues of an old Brit mag called Model Mechanics. More issues will be scanned and become available. See: http://www.model-engineer.co.uk/news/article.asp?a=5462 Other orphaned pubs will be added later. The site is busy and in England, so the PDF's take a few minutes each to download. The magazines are kinda nostalgic to skim, both for the articles and the now old-fashioned ads. But there are many excellent projects and how-to articles. GEAR MAKING: See Issue 4 of Model Mechanics for the start of an article on making gears. ------- Re: Cut gear [sherline] Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Thu Dec 24, 2009 9:02 am ((PST)) In sherlinex~xxyahoogroups.com, "rsimonus" wrote: > I saw new picture in photos folder by Jerry Kieffer. Jerry, can you tell me more about make gears? What kind of metal post that hold the gear and attach into rotary table. What kind of software do you use to run the stepping motor from rotary table? I assume you use gear tooth cutter from Sherline #3217. Can you tell me more sbout it and why did you cut that way in horizontal instead of vertical. Reid Reid: Will answer your questions in the order asked. #1. The gear blank holder is a standard Sherline End Mill holder. It is first mounted in the lathe to turn the blank to the correct OD and then transferred to the Rotary Table. #2. The rotary table in the photo is the Standard Sherline standalone CNC rotary table. It comes from Sherline preprogrammed for basic operations like divisions and degrees etc. #3. The holder shown is the P/N 3717 (see 3717 Sherline Instruction sheet at Sherline.com). The cutter was machined to form from A-2 drill rod and hardened per manufacturer instructions. #4. The R/T is mounted in the vertical position in the photo for two main reasons. First, it is simple and the most rigid mounting on a Sherline Mill. Second, it allows for easy and clear observation of the cutting process. Once you have machined the correct OD on a gear blank, the most effective way of determining correct or final cutter depth is by visual observation. This position allows you to easily observe tooth forming as you increase cutter depth until proper form is achieved. It also allows easy monitoring while cutting the rest of the blank. I also use a Horizontal mounting method with clear observation especially if a mounted microscope is used on small items. The scope mount works better in this position. I will also post a photo of this setup under my name in the photo section. This photo shows a custom cutter holder, however the standard Sherline holder will work in this position also. Jerry Kieffer ------- NOTE TO FILE: GEAR TEMPLATE GENERATOR WEBPAGE. Here is a Canadian woodworking site that amongst other really good projects has a gear generator program. Input the gear specifications and print out a paper template that you can affix to wood or phenolic or similar material; and then saw out the gear with bandsaw or jigsaw or scroll saw or coping saw or fretsaw or whatever, and sand to the line. The gears may not be as precise as CNC machined ones, but should be fine for toys and wood clocks and other neat projects. http://woodgears.ca/ ------- Gear thickness question [atlas618lathe] Posted by: "John Bump" johnbumpx~xxgmail.com Date: Mon Jan 18, 2010 9:58 pm ((PST)) I'm trying to cut a metric thread that requires me to use the 40 and 44 tooth gears beside each other. I put them on the bushing, put it on the banjo, tighten it, and it won't turn. If I push a little, the gear pair will suddenly be loose and moving back and forth in the banjo: the nut has loosened. When I compare them to another pair of gears, they look like they're much thicker than other gears, so it appears that the nut and washer are tightening against the gear rather than against the bushing, which is supposed to be somewhat longer than the gear pair. Both gears appear to be nearly unused. In fact, the 44 still had a bit of casting flash across one of the two keyways before I removed it. When I measure their thickness at the hub, rather than the face, the 40 appears to be about 0.379" and the 44 appears to be about 0.385" thick. Other gears, like the very well-used 64's, appear to be more like 0.370" thick. That indicates to me that this pair of gears is something like 0.015" thicker than other pairs of gears, which seems to be greater than the bushing depth. Has anyone else experienced this? I'm a little tense about facing a gear in the lathe. If I screw it up, it's gone. Do I try and face both sides? How do I hold a gear without screwing up the teeth? The only thing I've been able to come up with is a mandrel between centers, but it'd have to be a very, very, very slight taper to prevent the gear sitting slightly skewed, and then again I'm back to screwing up the gear. What do you suggest? thanks for any help... ------- Re: Gear thickness question Posted by: "Dean" deanwx~xxbmi.net Date: Mon Jan 18, 2010 11:31 pm ((PST)) That small difference in thickness can probably be taken down with some 60 grit wet or dry paper. Do it on a good flat surface, and the sides should stay true enough. To hold them in a chuck, use something on the jaws, between the gear and jaw surface. A piece of thin brass strip, something cut from a plastic milk bottle, or like that should do. That's how I do it when I face brass gears in a steel jawed chuck. Put something flat behind the gear when you mount it in the chuck so it doesn't wobble when you tighten the jaws. Take that piece out before you start the lathe. Just tighten the jaws enough to hold the gear snug. Not tight. Take light cuts. This stuff cuts easy. It won't take you long to remove a few thou. Dean ------- Re: Gear thickness question Posted by: "anthrhodesx~xxaol.com" Date: Tue Jan 19, 2010 8:20 am ((PST)) John: For holding the gears use pot chucks. Take a piece of round stock about 1/4" larger in diameter than the OD of the gear. Put it in your chuck and mark it at the #1 chuck jaw (so you can return it to its original position for concentricity). Bore it out so that the gear will just barely fit into it, bore depth a little less than the intended thickness of the gear. Now make 3 or 4 radial cuts around the part where the bore is located. These cuts don't have to be exact but they should be approximately equally spaced. Insert the gear in the bore and clamp it with a hose clamp around the slit part. This will distribute the load equally on all gear teeth and hold the gear concentric with the spindle. You could also use this for boring the gear if that were necessary. You need separate pot chucks for each diameter of gear. The flex walls should be thin enough to bend in without too much difficulty and thick enough to prevent localized pressure. You may see I'm suggesting roughly 1/8" wall thickness but this doesn't have to be exact. Hope this helps. Anthony Berkeley, Calif. ------- Re: Gear thickness question Posted by: "twocts4me" isaac_leyvax~xxdot.ca.gov Date: Tue Jan 19, 2010 12:53 pm ((PST)) John, Anthony, I recently picked up a 101.21200 myself and noticed the same issue of A & C position gears binding when tightened. I'm new to machining and don't feel confident enough about machining down the gears. Wouldn't it be easier to find a slightly longer stud bushing (or make one) that would allow the gear to spin freely between the bushing and the washer? If the new bushing was too long, it seems it could be machined down and if ruined in the process would be no big deal to just buy another and try again rather than risk ruining an unreplaceable gear by cutting them down? Any comments or other ideas would be appreciated? Isaac ------- Re: Gear thickness question Posted by: "anthrhodesx~xxaol.com" Date: Wed Jan 20, 2010 8:09 pm ((PST)) Isaac: The longer bushing would free the gears and allow them to spin on the stud but it won't solve the actual problem. It's not practical to mesh gears of different widths in a compound gear train. The gears may interfere with each other. Let's suppose you have a gear that's a little wider than standard mounted on a bushing next to the headstock and a smaller diameter gear mounted outside of it. Then you mount a large gear on a second stud to mesh with the second gear and a smaller gear also mounted on the second stud inside of the outer gear. All these gears are standard width except the inside gear on the first stud which, as suggested before, is a bit wider than standard. You should be able to see that the larger gear on the second stud will rub against the wide gear. If you can't visualize this, build it on your change gear banjo. Put a thin shim on a bushing, 10 or 15 thou, next a 40, then a 36. Mount these on the banjo at the extreme end of the long slot. Next mount a 20 on a second bushing and a 48 outside of it and install it on the long slot closer to the leadscrew position. Don't mesh the gears but leave the second stud slightly loose so that you can try to slide the gears into mesh. When you try to mesh the gears, you will see that the 48 runs into the 40 before it can reach the 36. Now back off the nut on the second stud so that you can mesh the 40 with the 36 and tighten the nut in that position. You will find that the gears are locked up by the 48 jammed against the side of the 40. Please tell me if this clarifies the issue for you and why you have to reduce the width of the wide gears to the same as the standard gears. Anthony Berkeley, Calif. ------- Re: Gear thickness question Posted by: "twocts4me" isaac_leyvax~xxdot.ca.gov Date: Mon Jan 25, 2010 3:54 pm ((PST)) Anthony: Thanks for the response. Yes I see the problem. Rather, it's an issue of the adjacent gears binding along their respective faces in the vertical plane. I guess my only recourse now would be to machine the gear thickness (or lap) to proper thickness. Looks like it will be a while before I start screw cutting - going to be needing general machining practice first. Just wondering why Sears/Atlas let a defect in the gear specs like this go through quality control. Any idea if this is a common problem with the 101's. Thanks, Isaac ------- Re: Gear thickness question Posted by: "Uldis Stulpins" u_stulpinsx~xxyahoo.com Date: Mon Jan 25, 2010 9:17 pm ((PST)) The gears are shared with the Sears Craftsman 109... (hobby) series lathes also. There's probably some swapping going on constantly with new buyers of old lathes from both camps looking for missing gears. My own set is made up of gears of varying thicknesses, some with crazy run-out that tighten up or even stop turning as they revolve and still others suffer from intergranular corrosion which causes the metal to swell in places, making any gear O.D. diameter measurement an exercise in averaging numbers. Recent mention has been made about steel change gears, and that has got to be the way to go! Uldis ------- worm gear [taigtools] Posted by: "Guy Smith" mguysmithx~xxyahoo.com Date: Tue Feb 2, 2010 6:28 am ((PST)) On the subject of making worm gears, I have had some reasonable success in making a number of fairly small worm gears with a pretty straight- forward system. I turn an aluminium disc to the required outside diameter and then mount it on a riser made from scrap aluminium barstock. The tricky part is making sure you have the center of the edge of the disc exactly in line with the center of the headstock. I mount a tap of the size and pitch I want in the three jaw chuck and a small length of rod with an axial hole in the jacobs chuck on the tailstock. I can use this rod to support the end of the tap while I advance the cross slide to feed the worm gear into the tap. Obviously I turn everything by hand, cutting only two or three thou at a time. It takes a bit of time but the results are quite good. Once I have the worm gear cut deep enough I usually turn on the lathe at its lowest possible speed and just let it spin away for a few revolutions of the wormgear to make sure everything is nice and smooth. Admittedly the hardest part is figuring out the precise size of the gear blank. I generally figure how many teeth it needs, convert that into inches and then get my diameter from that and add a little bit. Once everything is set up, it is pretty quick to determine if the blank is the right size. It takes me about ten minutes to turn out a 1.5 inch worm gear. ------- NOTE TO FILE: HOW A GEAR CAN BE MADE -- REALLY. For those of you still wondering how to go about making a simple gear, do yourself a really big favour and visit the following site: http://www.deansphotographica.com/machining/atlas/tumblergear/tumbler.html Here Dean Williams shows in great detail and with clear photos how he made a simple replacement gear for an Atlas 618 lathe. For your project, all you need in addition are the actual gear blank dimensions for yours. In this project, Dean uses a dividing head to space the tooth settings on the gear blank. You don't have a dividing head? Don't worry. You could alternatively use: Dean's Indexer Project, or a rotary table, or a home-made jig using other gears you have, or an inexpensive spin indexer, or a wooden disk made to a circumference matching the length of a paper strip marked out with the divisions needed (printed on your printer, or even hand drawn using a ruler before the paper strip is glued to the disk rim), or a wooden disk with a section of bandsaw blade screwed to the rim such that the number of blade teeth is a multiple of the gear teeth needed. (When using a wooden disk, the accuracy is improved by using the biggest disk practicable in your setup.) Here is one quote from Dean's notes on that page that made me a real fan. "I have a couple of books that tell all kinds of stuff about gears. Most of it is not really useful, or I just don't get it." Me neither. But Dean clearly shows us how. Thanks! ------- Re: bevel gears? [Metal_Shapers] Posted by: "David G. LeVine" dlevinex~xxspeakeasy.net Date: Sun Mar 28, 2010 6:20 pm ((PDT)) Jordan wrote: > A friend has asked whether it's possible to make for him a bevel gear. > The machine he wants to fix - a gardening implement - is not worth > spending on a milling gear cutter, so the shaper suggests itself. > But, is this a practical thing to attempt? > The original part is probably zinc based, and he wants to get better > durability in steel. > Precision would not need to be of a high order. > I'm thinking it could be just a little ambitious. > Any comments are welcome. Jordan While a shaper (or a planer) might work, the geometry suggests that it will not be very good. Bevel gears are not only 3 dimensional, but the teeth vary in size from one end to the other, and this is assuming standard straight cut gears, hypoid is MUCH worse. ------- Re: bevel gears? Posted by: "Clive Foster" clive_fosterx~xxtalk21.com Date: Mon Mar 29, 2010 7:43 am ((PDT)) Jordan: For all practical purposes conventional bevel gears can't be cut on a shaper; even on a milling machine there is a bit of interpolation needed to get an near enough to exact profile. It is possible to cut constant depth tooth bevels on a shaper, tho' it's easier on a mill, but you need to cut a pair as constant depth bevels won't run satisfactorily against proper bevels. The constant depth form was invented to allow adequate bevel gears to be cut easily on basic milling machines and, probably, shapers before the special purpose gear shaping and hobbing machines had been properly developed and become widespread. You will need to do some homework. Data needed is in older (pre WW2?) Machinery's handbook. Ivan Law's book on Gears and Gear Cutting in the Nexus Workshop Practice Series has something to say on the subject as do the older Brown and Sharpe gear-cutting data books. If you are really determined PM me and I may be able to find some "how to" info in slow time. Can't be sure, don't know if I've actually got stuff I've seen or just run across it. Hafta grind a tool to match the form of the spaces to be cut. Clive ------- Re: bevel gears? Posted by: "Jim S." mrjschmidtx~xxhotmail.com Date: Mon Mar 29, 2010 4:39 pm ((PDT)) You might want to pick up the book 'Gears and Gear Cutting' by Ivan Law. He shows how to make bevel gears with parallel teeth. His method uses standard involute gear cutters in a mill, but you might be able to adapt it to a shaper. You would have to make both mating gears to get them to work, though. Jim (Just a guy who likes to build stuff) ------- Re: bevel gears? Posted by: "clive603" clive_fosterx~xxtalk21.com Date: Tue Mar 30, 2010 4:02 am ((PDT)) To avoid possible confusion the terms constant depth, parallel depth, parallel tooth all refer to the same type of simplified bevel gear and tend to be used pretty much indiscriminately. Sometimes one text will use two variants! The job can be done on a shaper but it's easiest on a vertical mill with the gear blank axis horizontal and the cutter axis vertical. Essentially the idea is to use a standard involute cutter sized to cut the space at the small end of the teeth. After cutting a whole tooth space correct to nominal size with the cutter and blank mutually on axis, the cutter is moved vertically and the gear blank rotated by calculated amounts to make the tooth space wider and the tooth narrower at the large end so that things will mesh. You can either buy a cutter or make one using the method given in Ivan's book. Clive ------- Re: bevel gears? Posted by: "Jordan" jwprincicx~xxbigpond.com Date: Tue Mar 30, 2010 3:43 pm ((PDT)) Thank you very much gentlemen, You've put me onto the right track. As it happens I do have Ivan Law's book, just didn't think to look it up, as I didn't expect it to have info on bevel gears I guess. It has exactly the info needed for this job. It's not a myth - model engineers really are inventive. Jordan ------- Making Gears [Min_Int_Comb_Eng] Posted by: "brooklandsauto" brooklandsautox~xxyahoo.ca Date: Sun Oct 24, 2010 3:59 pm ((PDT)) I cannot afford to buy an indexing head but need to be able to make gears. I have a small lathe /mill combo, drill press and a lathe that I built myself. Does anyone know how I can make gears with the equipment that I have? ------- Re: Making Gears Posted by: "Stan Stocker" skstockerx~xxcomcast.net Date: Sun Oct 24, 2010 5:46 pm ((PDT)) Greetings, If you are going to cut fairly small sized brass and aluminum gears then you can use some pretty minimal equipment. A shaft with a protractor on one end and an adapter / mandrel to hold the work can be used for tooth counts that are in whole degrees. Pass the shaft through some nicely aligned holes, and fix up some means of locking the shaft. A circle of stuff (wood/ply/aluminum/whatever) of a circumference on n cm, inches, half inches, whatever unit of measure works can replace the protractor for other counts. Single point gear cutters can be ground or machined and hardened, and mounted on shop made arbors. I've heard of folks adapting cheap 5C spindexes for this application. I'm sure it could be done with good results, all you would needs is a few collets and a way to mount dividing disks/plates. Don't overlook using existing gears as master to generate plates or to use as dividing plates. You may have most or all you need already for your lathe. Steel gears are tougher. While you may be able to make cutters, buying is probably the best bet. I know this is sort of vague, but see if you can get your hands on some clockmaking books. Gears up to three or four inches diameter in brass are pretty common in the clock business. While many folks do in fact use dividing heads, many prefer direct indexing or using something really sexy like a CNC rotary table that can simply be told to step for 137 divisions, or 293, or whatever goofy number is needed. I've used them, want one, but at $600 on sale I'll live with direct indexing and dividing heads or rotary tables with dividing plates. Interlibrary loan might allow you to get your hands on one or more of the books on gear cutting for horology. Jim Huckabees American Regulator book includes plans for a direct indexing set up, as does Steven Conover's Make an American Clock Movement book. As you have a mill and lathe combo, is the mill head fixed? If so, can it be secured to the cross slide? That would allow you to use the lathe headstock for indexing - very cool, turn the mandrel, turn the OD of the blank, mount the dividing disk outboard, set up the mill, and cut teeth without ever unchucking the arbor and work. I believe Smartflix has the videos from Bill Smith on gear cutting (for clocks) as well as Jose Rodriguez's gear cutting videos. Setting up for home shop gear cutting on a budget does tend to be a "Make a tool to make a tool to make a tool to make a part" sort of effort, but once you have all the little bits and pieces sorted out it's a capability you have forever. If you want to get fancier without going totally over the top, you could mount a 72 or 90 tooth wormwheel to the outboard end of the lathe spindle, rig up a worm with a sector arm, and turn your headstock into a dividing head. Numerous folks have done this for Myford lathes, George Thomas published plans in one of his books. The British model engineers of a generation or two ago were truly superb at making and extending shop capability with time and ingenuity rather than credit cards! In the US, Rudy Kouhoupt followed this tradition and published many articles on making small shop equipment in Home Shop Machinist, although I really had heartburn with his article on milling in a drill press. He is the ONLY person I've heard of who claimed success doing this, and in all future articles I noticed he was always using a real mill, be it a small Sherline or a larger horizontal machine. Phil Duclos published plans for a universal dividing head sized for miniature machinists, also in HSM or Projects In Metal. I don't think I could teach you to cut gears via email, but hopefully this gets you headed towards some useful approaches and resources. Take care, Stan ------- Re: Making GearsPosted by: "kennedpjx~xxyahoo.com" Date: Mon Oct 25, 2010 6:20 pm ((PDT)) Hello, I just reamed a block of steel for a shaft to go through. On one end of the shaft I mounted a gear with the same number of teeth that Iwa nted to cut along with an indexing pin that fit into the gear teeth. A bolt through the block that pressed on the shaft and locked it in place was made. The other end of the shaft was the gear blank. I ground an old drill bit to fit the required toothform and mounted it in a shaft that was held between centers on the lathe. All that was left was to mount the block on the cross slide at the correct height for the tooth depth and cut away. Pretty simple and works a treat. Good luck with it! ------- Gears [LittleEngines] Posted by: "Gordon" glachnietx~xxgmail.com Date: Thu Nov 4, 2010 10:08 am ((PDT)) I have never have tried making my own gears, mostly because of the cost of the cutters. The process itself looks easy enough. I was wondering if anyone makes an end mill ground to the the proper shape. For the limited use of a model engine builder it would seem that an end mill would last for quite a while. Making my own cutters would probably be beyond my capabilities and equipment. ------- Re: Gears Posted by: "Hamilton Elliott" helliottx~xxmicroflex.ie Date: Thu Nov 4, 2010 10:48 am ((PDT)) Hi Gordon, Art Fennerty who wrote the MACH CNC package has recently released a program for designing and cutting gears on a CNC machine using ordinary end mills. But it must be CNC! The problem with buying conventional gear cutting cutters is that you need 8 to cut all the gears of a particular size. There are some videos on utube on how to create your own cutters and gears using a tool which is similar to hobbing and is often called hobbing but which gets a good approximation for "home" use. I can find and post the links if anyone is interested. Search for Shorty Leatherwood. But again he uses CNC. Regards, Hamilton ------- Re: Gears Posted by: "David Everett" deverett2003x~xxyahoo.co.uk Date: Thu Nov 4, 2010 10:53 am ((PDT)) Gordon: What you need is a copy of Ivan Law's book 'Gears and Gear cutting'. No.17 in the Nexus Special Interest books. (publishers of Model Engineer magazine). He describes how to make a flycutter type tool using simple techniques to get the correct shape. The involute gear cutters are (usually) expensive - you would need a king's ransom to be able to buy a complete set - and not really needed for small quantities of gears to be cut. Dave The Emerald Isle ------- Re: Gears Posted by: "Cliff. Johnston" moments-in-timex~xxcomcast.net Date: Thu Nov 4, 2010 11:10 am ((PDT)) David: Thanks for mentioning the book by Ivan Law. I had ordered it once only to be told that it was out of stock. A new batch appears to have been printed, and several sellers have them. Thanks to your reminder I bought one. Cliff ------- Re: Gears Posted by: "Gordon" glachnietx~xxgmail.com Date: Thu Nov 4, 2010 11:44 am ((PDT)) Thanks. I just ordered the book from Amazon for $6.92 + 3.99 shipping. CNC is not an option. I was thinking that an indexer would work with some kind of fixture to hold the blank. Gordon ------- Re: Gears Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca Date: Thu Nov 4, 2010 12:04 pm ((PDT)) Most spin indexers (is that what you mean?) only allow indexing in increments of 1-degree so you're limited in the choices for number of teeth. A nice idea is using a spin index with a stepper motor and belt reduction for turning it. ------- Re: Gears Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Thu Nov 4, 2010 1:03 pm ((PDT)) Ken, I am guessing a rotary table (CNC or manual) would be better than an indexer??? (Note: that is a question) DanD. ------- Re: Gears Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca Date: Thu Nov 4, 2010 2:01 pm ((PDT)) A rotary table has a large flat surface which prevents getting the mill spindle very close. You end up with requiring the gear to stick out and so it is not supported very well. Having to use a tailstock would make the mandrel more complicated since a center is required. It seems to me that a spin index would allow very short overhang and a 5c collet is pretty accurate. I saw a simple design that used a large pulley on the spin index with a cogged belt driving it from a stepper. It was a clean design that should be able to be built at low cost. Unfortunately, I can't find the web page. ------- Re: Gears Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Thu Nov 4, 2010 2:40 pm ((PDT)) I was considering a rotary table used on a mill. In my case, a Sherline rotary table used on Sherline mill. To be honest, I have never tried to cut any gears, just a thought. DanD. ------- Re: Gears Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca Date: Thu Nov 4, 2010 3:34 pm ((PDT)) How close can you get your mill spindle to the rotary table surface? ------- Re: Gears Posted by: "Jim" jjsbtalexx~xxyahoo.com Date: Thu Nov 4, 2010 3:53 pm ((PDT)) Check out this youtube of a gentleman in England. He makes a single tooth gear cutter using buttons. Calculation of button size is available on the net, but I've forgotten the urls. Pretty slick and the guy does fantastic work on his videos. http://www.youtube.com/user/myfordboy#p/u/5/7zMgJXMHcNs Jim ------- Re: Gears Posted by: "James Early" jwearly1x~xxverizon.net Date: Thu Nov 4, 2010 5:08 pm ((PDT)) You cannot use an end mill to hob gears as the basic shape is entirely wrong. This is the unit you need to cut gears. I have tried six or seven other systems with no success. I have made more than 50 gears for machine repair using one of these and every one of them worked perfectly! [Link to *bay dividing head with index plates and tailstock.] JWE Long Beach, CA ------- Re: Gears Posted by: "Rupert" rwenig2x~xxxplornet.com Date: Thu Nov 4, 2010 7:50 pm ((PDT)) I've cut a set of timing gears for my little engine using a rotary table with no problems using involute cutters. I mounted the gear blank on an MT adapter. Rupert ------- Gears Posted by: "James Wright" gunner312x~xxq.com Date: Fri Nov 5, 2010 11:38 am ((PDT)) I have been making my own gears for some time. I recommend "Making Gears the Easy Way" by Jose Rodrigues. Comes as a video that demonstrated the methods to use. Just google "Making Gears the Easy Way" Jim Wright ------- Re: Gears Posted by: "Cliff. Johnston" moments-in-timex~xxcomcast.net Date: Fri Nov 5, 2010 2:08 pm ((PDT)) There are several short clips on YouTube which are free and just as informative. In these economic times free is good J Cliff ------- More Gears [LittleEngines] Posted by: "frazer51" frazer51x~xxyahoo.com Date: Fri Nov 5, 2010 6:58 am ((PDT)) I cut the gears for my first engine, a Duclos' Odds & Ends, using the method he outlined in his book, The Shop Wisdom of Philip Duclos. He shows how to make a single point cutter using drill rod. The range of teeth, is very limited and the pitch is 32dp. I used a cheap spin indexer that I bought from Enco for about $25. I've cut three sets of gears for various engines, using his method. I now have a dividing head like the one on the ebay link in a previous post. I've never used it in the 12 years since I bought it. The last sets of gears that I've cut, I used my rotary table as an indexer with involute cutters that I bought off ebay. It's quick and easy to make an arbor to hold the gears in the indexer or rotary table and I've not found spacing to be a problem. There is a Yahoo group dedicated to gear cutting. Jose has a good video, available through Little Machine Shop, on cutting gears. Carl Felty ------- Re: More Gears Posted by: "Gordon" glachnietx~xxgmail.com Date: Fri Nov 5, 2010 10:20 am ((PDT)) It appears that it may be practical to build a cutter. Hopefully the book will be a little clearer on making your own cutters. My use is also mainly for timing gears where the most important thing is 2:1 ratio. The engine I am working on right now requires 32 pitch with 22 tooth and 44 tooth. Neither of these are able to be cut with a spin indexer with 1° increments but 18t/36t or similar in a different pitch should be close enough by changing the center distance slightly. On a similar vein there are module cutters which are metric available on eBay for $100 to $200 for a set of eight. I just spent $40 w/ shipping for the above gears so getting a complete set which I may be able to use again looks better. I am retired and do this for a hobby so time is not as important as it was when I was earning a living. Making the right cutter is obviously a better option. Gordon ------- Making a new gear [sherline] Posted by: "Pavel Kořenský" pavel.korenskyx~xxdator3.cz Date: Sat Dec 18, 2010 7:38 pm ((PST)) Hello, I need to make a new gear for the food processor (I hope that this is a proper english word for the piece of equipment which my wife has in the kitchen). The gear which I need to copy can be seen at http://img208.imageshack.us/img208/1494/img7149g.jpg The gear has 30 teeth, is approx. 31 mm diameter and 15 mm thick. The pinion which is driving this gear has 6 teeth, 7.8 mm diameter and it seems that it is not a standard "module" type of pinion, but it is very close to the "module 1" pinion. I am planning to make a new gear from brass, but I am not sure how to set up the whole thing. First part is simple. Turn the outside diameter on Sherline lathe, face it etc. But I am not sure about the milling setup. I have a rotary table and the tilting angle table. I have the P/N 3217 cutter and I also have the special set of gear cutters for "module 1" gears. I am thinking about mounting the rotary table on the tilting angle table, tilt the table 20 degrees (or something like that, I will use the old gear as a reference) and use the gear cutter. But I am not sure if the setup will be rigid enough for this type of work. Anyone have a better idea how to cut this type of gear? Thank you for any information. PavelK ------- Re: Making a new gear Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Sat Dec 18, 2010 8:13 pm ((PST)) Pavel, your verbal description is perfect. Your photo is clear enough. First question, can you buy a completed gear? If so, this may be the fastest way to complete the project. (But, you may not find further justification, to your wife, for the lathe and mill and further purchase of accessories. LOL) Second question, "How to set it up and cut the gear?" I'll admit it, I am stumped (without an answer). BUT, I am sure you will get the information you need here. I will have to think about it, myself. DanD. PS this is a herring bone type gear. The teeth are on a what angle to the axis of the hole of the gear? You are NOT using a CNC mill? ------- Re: Making a new gear Posted by: "Pavel Ko?enský" pavel.korenskyx~xxdator3.cz Date: Sun Dec 19, 2010 2:56 am ((PST)) Hello. No, it is not possible to buy a new gear. It is only possible to buy a new food processor, but this one is rather expensive (around 450 USD), so I am trying to fix it. And of course, I am trying to be a nice husband, too. I measured the angle of teeth to the axis and it is 20 degrees. No, I am not using CNC mill. PavelK ------- Re: Making a new gear Posted by: "Lee" LeeFairfieldx~xxHotmail.com Date: Sat Dec 18, 2010 8:29 pm ((PST)) Hi. Take a look at this YouTube video: http://www.youtube.com/watch?v=HAtziCsUj5Q&feature=related It shows just what you are talking about. It also includes info about choices of plastic. The best way to cut is with either a gear cutter or a hob. Grinding the bit on the 3217 is very difficult. Good luck Lee ------- Re: Making a new gear Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sat Dec 18, 2010 8:49 pm ((PST)) Hello Pavel, See: http://youtu.be/HAtziCsUj5Q I have cut many gears in brass as you describe. For rigidity, and to ensure concentricity, I would turn the brass blank to size and bore the shaft hole on the lathe, and then move the lathe chuck to the table without releasing the work. Cut the teeth, and then part the gear from the workpiece with a saw. Attach the gear to its shaft, then return to the lathe to face the saw cut side. David Clark in Southern Maryland, USA ------- Re: Making a new gear Posted by: "Pavel Ko?enský" pavel.korenskyx~xxdator3.cz Date: Sun Dec 19, 2010 3:04 am ((PST)) Hello David. Thank you for the video. So it seems that a rotary table and tilting angle table is a way to go. If everything will be ok, I will post a picture of a finished brass gear in a few days. PavelK ------- Cutting a helical gear - small problem :-) [sherline] Posted by: "Pavel Kořenský" pavel.korenskyx~xxdator3.cz Date: Mon Dec 20, 2010 6:31 pm ((PST)) Hello, a couple of days ago, I mentioned that I need to make a helical gear on a Sherline. I turned the brass blank on lathe, I moved the chuck with the blank to the mill, I figured how to fit the tilting angle table and rotary table under the mill etc. BUT, as always, the devil is hidden in the details.. There is a small (or, better to say a BIG) problem. For succesfull milling of helical gear, it is necessary to rotate the blank during cutting in sync with axis movement. Does anyone have some ideas, how to do it on a manually operated Sherline mill, without the CNC ? Thank you for any ideas PavelK ------- Re: Making a new gear Posted by: "Terry Looney" loon432x~xxverizon.net Date: Mon Dec 20, 2010 7:59 pm ((PST)) Hi Pavel: The gear you have is a helical gear. Unfortunately, the setup for cutting helical gears involves rotating the gear blank as the cutter moves axially along it. This is done by gearing the dividing head to the screw that moves the table in the X direction. If you set the blank at an angle only, the tooth profile will be too wide at the edges when the profile is correct in the middle, or too narrow in the middle when the profile is correct at the edges. Not really your problem, but the actual helical angle will vary with a change in the number of teeth you are cutting on any given gear of the same pitch. You will be ahead if you can find a replacement part. Terry Looney PS A herringbone gear is a double helical gear. Its advantage is that the axial forces are neutralized because the gear has both a right hand and left hand helical angle. ------- Re: Cutting a helical gear - small problem :-) Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Tue Dec 21, 2010 7:27 am ((PST)) Pavel: I do not have your gear in my hand nor have you shown the gear arrangement. However from the photo you supplied the tooth form does not appear to be a true slightly curved Helical tooth form. It appears to be a simple standard straight line tooth on a slight angle. I would suggest you machine the simple form that you see in front of you using the setup you mentioned. If none of this works out, then the simplest way out of this will be to machine both gears to a tooth form you are comfortable with since you say you have a complete set of cutters. Jerry Kieffer ------- Re: Cutting a helical gear - small problem :-) Posted by: "Terry Looney" loon432x~xxverizon.net Date: Wed Dec 22, 2010 11:16 am ((PST)) Hi Pavel, I agree with Jerry K. Remanufacture both gears as straight spur gears (which are cut easily on a manual machine). Spur gears are a little noisier, but are actually stronger than helical gears. Terry Looney ------- Re: Cutting a helical gear - small problem :-) Posted by: "Pavel Kořenský" pavel.korenskyx~xxdator3.cz Date: Wed Dec 22, 2010 2:49 pm ((PST)) Hi Terry: Actually, it was my first idea. Problem is, that the helical pinion is made (probably milled) directly on the motor shaft. PavelK ------- Re: Cutting a helical gear - small problem :-) Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Wed Dec 22, 2010 4:39 pm ((PST)) Pavel: Terry is correct on his explanation of machining a typical 45 degree Helical gear. However in your case, the sample appears to have teeth that are less than a 15 degree angle. If so, the teeth can simply be machined as you originally thought without any noticeable effect. While technically it will not be absolute perfection, there will be nothing that will affect tooth strength, fit or efficient operation of the gear. Jerry Kieffer ------- Re: Cutting a helical gear - small problem :-) Posted by: "Pavel KoĹTenskĂ˝" pavel.korenskyx~xxdator3.cz Date: Wed Dec 22, 2010 5:26 pm ((PST)) Actually, the angle is exactly 15 degrees. It seems that I will try to mill the gear on my current setup and we will see. After all, it is only a small piece of brass and I already abandonned the idea to give a new gear to my wife as a Christmas gift :-) Best regards PavelK ------- Re: Cutting a helical gear - small problem :-) Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Wed Dec 22, 2010 5:57 pm ((PST)) Pavel, I do hope your Christmas dinner does not revolve around getting that thing repaired. If so, I know one of Santa's elves will be working late into the night. DanD ------- Helical gear - from theory to practice {sherline] Posted by: "Pavel Kořenský" pavel.korenskyx~xxdator3.cz Date: Wed Dec 29, 2010 7:10 pm ((PST)) Hello, I uploaded several photos to the Yahoo photo album http://groups.yahoo.com/group/sherline/photos/album/330407123/pic/list I decided to try milling the helical gear without table rotation during the cut and it seems that Jerry Kieffer was right and the result will be usable. The gear fits against the pinion without any problem. Tomorrow, I will part the gear from the blank, face the other side, drill and tap the hole for the screw which will hold the gear on the shaft and I can test the assembled gearbox. PavelK P.S. The original gear was made from some kind of plastic. The pinion is made from steel. The gearbox was filled with some kind of vaseline. Although I know that brass gears generally do not need any lubrication, I suppose that I will not make a mistake if I will fill the gearbox with a generous amount of vaseline. Am I right ? ------- Re: Helical gear - from theory to practice Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Wed Dec 29, 2010 8:01 pm ((PST)) Pavel: The gear you are replacing was some sort of plastic while the other gear is brass? If that is so, the reason for the plastic is that it is the sacrificial gear so if too much strain is put on the gear train, the plastic gear will strip preserving the rest of the appliance. Per replacing the plastic gear with a brass gear may not be the best idea. The continuing straining and re-straining of the gear train could damage the motor or some other important part. (trying to be gentle here) "Suggest" to your bride, she stop overloading the appliance . I do wish you only good fortune when you "suggest" this. Per loading up the gear box with some sort of grease.... 2 metal gears meshing each other.... "you betchum Red Rider", load up the gear box with a "food grade lubricant". I have no idea what to recommend when it comes to that designation. DanD. ------- Re: Helical gear - from theory to practice Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Thu Dec 30, 2010 5:35 am ((PST)) No Vaseline! It degrades over time and develops a smell. Jerry G ------- Re: Helical gear - from theory to practice Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Thu Dec 30, 2010 9:13 am ((PST)) Pavel: I am happy this worked out for you, at least so far. However I would suggest that you lubricate steel on brass gearing. If your gear box is sealed, an excellent lube would be the heaviest gear lube available at a auto parts store or STP. But I suspect that your gear box is not sealed. In that case I would suggest gear grease available from any appliance parts store. Or any outlet that handles a large range of lubricants. Jerry Kieffer ------- Re: Helical gear - from theory to practice Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Thu Dec 30, 2010 9:29 am ((PST)) Pavel: The reason I recommend a "food grade" grease is "in case" it comes in contact with any of the things your bride is making. The food grade grease will not make you sick or kill you. DanD. ------- Re: home brew worm gears [taigtools] Posted by: "luv2bsailin" luv2bsailinx~xxyahoo.com Date: Mon Dec 27, 2010 11:14 pm ((PST)) Inx~xxyahoogroups.com, "davideggy2" wrote: >>>> Hi, I've done this a couple times before on a larger lathe, but should be fine on the Taig. I used a fast spiral tap like Steve suggested. I drilled a blank of delrin ,using the closest hole saw to the size I needed, which gave me a 1/4" center hole. I fastened a block of wood to the cross slide the correct thickness to put the blank at center height. Drilled and tapped a 1/4" hole in the wood, dropped the blank on and fastened it loosely with a bolt so it would spin freely. I let the delrin overhang the wood a little so chips wouldn't build up but would still support it near the edge. This is only going to work well if the gear is small enough to mount in front of the tap on the cross slide where the cutting action is down into the blank. You might have to extend the wood piece out in front of the cross slide. I used the slowest spindle speed and just advanced the cross slide until contact was made. The blank started to rotate immediately and I just kept feeding until threads started to form. At the end of the first rotation, the tap will skip or click over into the first thread and continue on. As you approach the right diameter and thread depth, this click will lessen until there is a smooth transition. If you end up with one too many teeth, advance the cross slide and keep going. You'll get that click/skip again until you get to the right dia for one less tooth. It's really easy and very neat. Dave <<<< On 4 November 2010 03:50, luv2bsailin wrote: >>> Wow, what a great group. Thanks for all the input guys. You've given me the confidence to charge ahead with this project. One other question, do you think ACME screws are a better choice than standard 60 degree threads for worm screws? They look more like existing worm gears I've seen, and I happen to have a bunch of scrap pieces in my junk box. Since the torque load is low (one ft-lb or less probably), I'm thinking cheap hardware-store threaded rod might be OK, and the threads are finer so the big wheel could be smaller for the same ratio. I guess I ought to just try the threaded rod since I already have taps for it. If it doesn't work well I can always order an ACME tap. Anyhow, thanks again guys. I'll let you know how it turns out. Jim McMillan <<< Tony Jeffree wrote: >> The threaded rod approach should work just fine - there's no >> point going for ACME threads. Regards, Tony "luv2bsailin" wrote: > Standard thread it is! I'll look for something a little smoother than > the cheapo hardware store threaded rod. Thanks again guys. > Cheers, Jim McMillan Hello again guys, I finally got around to making some worm gears as discussed here. I was going to build a special fixture, but then I realized that my Taig lathe and mill could be pressed into service with minimal effort. First I cut a roughly 4 inch diameter disc from a 1/2 inch Delrin plate using a hole saw on the drill press. Then I modified one of the Taig blank lathe arbors to hold the disc via the 1/4 inch center hole left by the pilot drill on the hole saw. The headstock/arbor/disc setup was then removed from the lathe and clamped on the mill table. A 3/8-16 spiral tap was chucked up into the mill spindle and brought up against the edge of the Delrin disc. (I did not pre-shape or pre-gash the disc edge in any way, all the cutting was done with the tap. Also, the mill spindle had to be rotated 90 degrees for clearance on this big disc, but a subsequent smaller one was done with the spindle vertical.) Then I just ran the mill spindle and let the Delrin disc freewheel while advancing the edge of the disc into the tap, moving a few thousandths at a time and waiting for the chip-making to subside before advancing again. Go slowly, being careful not to put too much side load on the whole setup, give the tap time to do it's thing. Once I had about 1/3 of the diameter of the tap buried edge-on into the disc, I backed off and cleaned up the fuzz on the Delrin with an old toothbrush. I then sawed the head off of a nice shiny stainless 3/8-16 bolt and installed it in the mill collet in place of the tap. With the mill running and minimal preload between the worm (bolt) and the new wheel I was not able to make it skip a tooth by gripping the lathe headstock pulley by hand. A very satisfying result. I have since made a smaller wheel out of 5/8 brass rod using the same technique with great results. Probably wouldn't hurt pre-shape the disc edge a bit as Dave suggested, mainly to save wear and tear on the tap. This could probably be done in the same setup by side-cutting with an endmill sized for the root diameter of the worm screw. One thing I'm still puzzling over is that I did not hear or feel the "skip" that Dave mentioned should occur as it finds it's proper diameter. Maybe I was just lucky and hit the right diameter twice in a row, or maybe there is something inherently "self-leveling" in the process. Examining the teeth under magnification revealed no partial or misshapen eeth. So how does one measure or calculate "pitch diameter" on worm wheels, is it the same as the O.D. or something less as on "regular' gears? Cheers, Jim McMillan ------- Re: Metric gears [atlas_craftsman] Posted by: "peterh5322x~xxrattlebrain.com" Date: Wed Dec 29, 2010 12:05 pm ((PST)) > I have a 12" craftsman lathe with a quick change gear box,I have had it > for over 15 years.I started looking thru the stuff I got with the lathe > and found a set of 12 gears in the origional box marked metric gear > set,It also had the invoice and the price $60. > My question is whare are they used? are they installed in the quick > change box or are they used to replace the factory gear set that came > with the lathe? I have never had a need to cut metric threads so I never > investigated the how they are used. > I purchased the lathe from the origional owner and have just about all > the accesories that could be bought at the time except the taper > attachment. Depends upon the particulars of the gears, but in the most usual case, these are placed between the reverser and the gearbox. For an 8 tpi leadscrew, the usual metric transposer is 100/127, but an optional transposer (with a constant 0.020 percent error over all metric pitches) is 37/47. With an Imperial gearbox and an 8 tpi leadscrew, usually only two positions of the box will give usable metric pitches. Of course a box has as many as five ranges, so that is 2 * 5 = 10 usable metric pitches, all related by 2. To get the remaining metric pitches, the reverse shaft gear (the input to the transposer) may requires as many as 8 additional gears. Imperial pitches require multiple factors of 2. Metric pitches require multiple factors of 5 and 25. ------- Re: Metric gears Posted by: "Glenn N" sleykinx~xxcharter.net Date: Wed Dec 29, 2010 1:04 pm ((PST)) Go to the files section and in the operation and parts manuals folder there is a file "Atlas QC Gearbox.pdf" In that you will find the chart and description of how to use those gears with the QC gearbox. ------- Gear cutting setups? [sherline] Posted by: "martin.machining" martin.andersonx~xxgmail.com Date: Tue Feb 22, 2011 1:15 pm ((PST)) Does anyone know where I might find photos of Sherline gear cutting setups? I've recently acquired a rotary table and am (naturally) thinking about doing some gears. ...however, I find myself having difficulty visualizing the various work-holding options. It's not urgent or anything (heck, haven't decided between single-pointing vs. eBay involute cutters, and I don't yet have any way to mount the table at 90deg), but if folks have suggestions I'd be grateful. Most of the resources I've found are really more about the gear cutting process (and math), which I understand, and don't really cover how one goes about setting things up in the first place. ------- Re: Gear cutting setups? Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Tue Feb 22, 2011 2:05 pm ((PST)) Take a look at my photo album for a few illustrations: http://groups.yahoo.com/group/sherline/photos/album/937902184/pic/list And files: http://tech.groups.yahoo.com/group/sherline/files/D.C.Clark/Gear%20Cutting/ First question is what size gears? That will determine how you must fixture and machine your blanks. Will you make small gears, an inch or so in diameter, cutting the teeth in a rod? Or larger gears out of blanks cut from plate? Rod for smaller gears will remain in the lathe chuck. For the larger gears you'll have to make some sort of arbor. Design of the arbor will depend on what sort of hub the gear will have, and maybe whether it will have spokes. Once you narrow things down a bit, I can make some very specific suggestions. If you just want to cut any old gear for the fun of it, I'd get some 1 to 2 inch ABS plastic rod, buy an involute cutter of a pitch you think you might find useful, chuck it up and have at it. I highly recommend you start with the plastic. Way cheaper and more forgiving to play with. David Clark in Southern Maryland, USA ------- Re: Need two 48T gears for quadrant [atlas_craftsman] Posted by: "jgedde" john.geddex~xxaeroflex.com Date: Tue Mar 15, 2011 5:08 pm ((PDT)) "sgwillis" wrote: > I am looking for the 48t gears on the quadrant on a Craftsman 12" model 101-28990. Sears is a bit pricey and on backorder. Checked ebay and none showing up. Any suggestions. Thanks. < I've replaced a number of gears on my lathe with cast steel gears from a local supplier (Beardslee). The off the shelf gears are way too fat, have a hub, and have an ID too small. No problem... I simply chuck them up, indicate them true, face them to the right thickness, bore them to the right ID (.750 if I recall), and broach two keyways using a chinese tool. My first keyways were just filed in! Sounds much harder than it is. Gears are 16 pitch, 14.5 degree pressure angle. Cheers! John Oh. And by the way, the steel gears are cheap! No gear I've bought and modified was over $12! ------- Atlas Pick-A-Gear photos [atlas_craftsman] Posted by: "db45acp" db45acpx~xxyahoo.com Date: Tue Mar 29, 2011 2:10 pm ((PDT)) I finally got around to taking some photos of my Pick-A-Gear Rack. I have uploaded them to my album entitled "DB45ACP Stuff" in the Photos section. http://groups.yahoo.com/group/atlas_craftsman/photos/al bum/1447494289/pic/list Descriptions and rough dimensions as well. Dan ------- Re: Atlas Pick-A-Gear photos Posted by: "mertnedp" pdentremx~xxforterie.com Date: Tue Mar 29, 2011 2:15 pm ((PDT)) That is slick! Takes less space than the pegboard that I use. How is it for lifting the gear out of the rack? Do they catch on the teeth? ------- Re: Atlas Pick-A-Gear photos Posted by: "Dan Buchanan" db45acpx~xxyahoo.com Date: Tue Mar 29, 2011 3:12 pm ((PDT)) They actually go in and out pretty easily. It's not like something that is used daily or constantly, it is just an indexed holder for the gears so it shouldn't see a lot of use. I think it was well conceived and was a practical solution for this accessory. Easy to see, select and holds all the gears. It could probably be easily reproduced on a mill using flat sheet stock on a sub-plate. Cut the slots with a 1/2" endmill to appropriate lengths then bend and form the arc shape around a cylinder with a vise I love the graphics of that era. That would be an excellent final touch to add with a simple silkscreen template. Dan ------- Re: Atlas Pick-A-Gear photos Posted by: "mertnedp" pdentremx~xxforterie.com Date: Tue Mar 29, 2011 6:24 pm ((PDT)) I would likely use ABS pipe and mill out the slots. Project Number 1100000 on the list! ------- Making gears info [barstockengines] Posted by: "bear" rnjtalbottx~xxgmail.com Date: Fri Apr 1, 2011 3:14 am ((PDT)) I found this web site which had easy to follow instructions. I made the hob (the straight cutting one at 14.5 degrees) and made two gears that turned out really well. Check out: http://jzcomputer.com/SpurGears Ron ------- Gear blank arbor? [sherline] Posted by: "Martin Anderson" martin.andersonx~xxgmail.com Date: Thu Mar 31, 2011 12:14 pm ((PDT)) Does anyone know of good sources for info on work-holding for gear blanks, preferably in a manner suited to use with the rotary table? I'm not exactly a wizard at work-holding, having done pretty much everything with a mill vise until now. I have some chuck+arbor-type ideas in mind, but I figured I should check before disappearing too far down the rabbit hole. Martin A. ------- Re: Gear blank arbor? Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Thu Mar 31, 2011 2:39 pm ((PDT)) Martin: See my files and photos, both under D.C.Clark, for some examples. I can help you out if you give me some more info: Gear specs -- diameter, pitch, number of teeth, bore diameter, thickness, section, spokes? Will you be making more than one (blanks can be stacked). Material? Involute or cycloidal form? Using a commercial cutter, or grinding your own? Can also suggest answers to the above if you tell me what it's for. There's a small universe of difference between making a plastic gear for a light duty, low speed application, and making a case hardened steel gear for a high speed, high powered transmission. David Clark in Southern Maryland, USA ------- Re: Gear blank arbor? Posted by: "Steve Wan" stewanx~xxgmail.com Date: Thu Mar 31, 2011 7:19 pm ((PDT)) Hi Martin: Do visit David Clark's photo section on gear cutting and Pavel Korensky who made a helical gear for his wife's fruit blender in brass when the plastic gear worn out. As for work holding, I made a simple aluminium rectangle pillar stand and bore a hole to hold a screw thread with same pitch as the Sherline 3 jaw chuck. As for indexing I may use a digital meter one end or an index plate of required drilled holes. If the blank is too long I can fasten the support using Sherline tailstock on the mill table. I'm cutting my gear with a single lip cutter which I made using a cutter- grinder I made (photo: Steve's workshop-Singapore) Or you can buy work holdings from Sherline to save all the trouble making! Hope this helps, Steve-S'pore ------- Re: Gear blank arbor? Posted by: "Martin Anderson" martin.andersonx~xxgmail.com Date: Fri Apr 1, 2011 7:18 am ((PDT)) Mr. Clark: I'm building the entire gear train for a small device, so I haven't entirely sorted out the mechanical requirements (I don't have to mesh with an existing system), but I presently expect them to be 32-pitch, 20deg pressure angle, 3/16" face width, 3/16" bore, 12 to 96 teeth (basically, 3" would be the largest). Don't particularly care if there's a hub projection, so I'll probably have one for simplicity of shaft-attachment, maybe 5/16" projection or so. Very low speeds, on the order of 5-10 revolutions/minute. Materials will be primarily 6061 and maybe one or two nylon/delrin (to give a failure point, although at those RPMs I won't really need one). If it all works out nicely, future versions may be of more visually-interesting metals (eg: brass). As for cutters, I'll probably be eBay'ing some involute cutters and likely cutting the gears one at a time (maybe stacking 2 back-to-back, but with the hubs I'd probably not stack further than that). I'd considered grinding a single-point HSS bit, but I'm fairly terrible at grinding (well, and my grinder is dying) so that'd be more of a future endeavor. Steve-S'pore: which Sherline pieces are you referring to? I'm considering something along the lines of what you described, but frankly if I can buy it I'd rather do that (instead of potentially mucking up the work-holding, leading me to mucking up the gear, leading to me trying to figure out what exactly went wrong and slowly going mad.....) Thanks to both of you for your replies! Martin A. ------- Re: Gear blank arbor? Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Fri Apr 1, 2011 2:09 pm ((PDT)) Hi Martin. Quick response, more to come: Good choice of size and type. I've probably done more 32 pitch gears than any other on my Sherlines. Have a full set of 32P cutters from McMaster. Well worth the investment considering the number of gears I've produced. It's a nice workable size for small mechanisms, and well suited to making on Sherline sized machine tools. Here's a motion train for an electric clock I'll finish one of these years: http://tinyurl.com/3fprhkh It contains several of the gears you mention. The wheels are of 1/8" sheet and the pinions from bar, all alloy 360 brass. I turn the hubs separately and press fit them into the finished wheels. Much easier, enables stacking, saves material. I would not make any gear of aluminum unless you can have it hard anodized after machining. Bare aluminum on aluminum has about the highest coefficient of friction of any combination of two metals. Even the best made involute gear set will have some sliding friction. Alloy 360 brass is the "unit candle" of machinabilty. But for easy cutting while getting some practice I'd suggest ABS plastic. Delrin can be stringy and tends to tear. All of the gears and other mechanical components of my Fulton engine model are ABS. See: http://tinyurl.com/3obglop Those gears are 12 pitch. I have a box full of various arbors I've made over the years. I'll sort them out, take some photos, and follow up with some suggestions on how they're made in the next day or so. DC ------- Re: Gear blank arbor? Posted by: "R.L. Wurdack" dickwx~xxnwlink.com Date: Fri Apr 1, 2011 3:00 pm ((PDT)) David: As cutters are a somewhat expensive investment, I have considered what pitches to jump in on. I have thought about 24, 30 and now you've added 32 to the list. 24 is the pitch Sherline uses for the threadcutting attachment, 30 is speced in a clock design I may build if I live forever. Were there other things that drove you to arrive at 32? I am a firm believer, nay, a true fan of ABS. It is a great material for a lot of applications. Cheap, available, easy to machine, durable, gluable, and ad and ad. Has anyone plated or flashed metal onto ABS? It makes great electronic enclosures unless you need a Faraday shield. D. ------- Re: Gear blank arbor? Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Fri Apr 1, 2011 6:34 pm ((PDT)) Hi Dick: It's kind of a "chicken or egg" question. I'm not really sure that I remember which came first -- did I choose that pitch because of a particular project, or design the project to the pitch. I think it may have come about in connection with this clock design: http://tinyurl.com/3d9t6vy I was thinking about clock gearing and made a solver spreadsheet in Excel to calculate different gear combinations for motion works. With all variables unconstrained there are, of course, a couple million solutions. So I began adding constraints: all gears the same pitch, no gear of less then 12 teeth (about the practical minimum for an involute form), none greater than 4.5 inch diameter (about the practical maximum for a Sherline lathe) as many as possible the same tooth count to facilitate manufacture. This narrowed it down to a dozen or so, one of which called for the minute and hour wheels to each have 144 teeth -- 4.5 inch diameter at 32 pitch. It occured to me that with such big wheels, one could tell the time by reading the position of the wheels without the need for conventional hands. So I made the wheels out of clear Lexan with inlaid brass strips instead of hands. Made a pretty spiffy looking desk clock, I think. Best, DC ------- Re: Gear blank arbor? Posted by: "R.L. Wurdack" dickwx~xxnwlink.com Date: Sat Apr 2, 2011 7:05 am ((PDT)) 32 it is. Love the clock. D. ------- Re: Gear blank arbor? Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sat Apr 2, 2011 2:28 pm ((PDT)) Hello Martin and all, I've posted a pdf on the subject in my folder. Look in: Files > D.C.Clark > Gear Cutting or link: http://tinyurl.com/3jygcy8 DC ------- Re: Gear blank arbor? Posted by: "Martin Anderson" martin.andersonx~xxgmail.com Date: Mon Apr 4, 2011 10:24 am ((PDT)) Well, normally I thank people off-list to avoid cluttering things up, but in this case I thought perhaps it would be best to be more public (also, I figured if I kept the subject line unchanged this will at least stay in-thread). Thank you everyone for the recent gear discussions! ...but particular thanks to Mr. Clark, whose contributions have been extremely valuable in several ways. Thanks again, Martin A. ------- Atlas Gear Repair ??? [atlas_craftsman] Posted by: "none" garybauer46x~xxyahoo.com Date: Thu Apr 14, 2011 9:31 pm ((PDT)) Hey Guys, Is there a method for repairing the Atlas zamak gears that have missing teeth? If they were iron gears I'd simply braze-fill and remachine the needed teeth. Can these zamak gears be brazed with that fancy "aluminum" braze rod of mostly zinc alloy? The filler is a rather low temp process as I recall. Thanks, Gary ------- Re: Atlas Gear Repair ??? Posted by: "Cindy & Wayne Burner" burners4x~xxcomcast.net Date: Fri Apr 15, 2011 3:36 am ((PDT)) Gary, I have repaired these by drilling a hole, insert a small brass pin, and build up JB Weld around the area enough to to cover tooth size. After hardening, the material can be hand filed to a perfectly shaped replacement tooth. Similar to what a dentist would do when putting a cap on a tooth, just a lot cheaper :>) The repair is close to the right color too. This repair is quiet when running, and has not broken since the repair was done 10 years plus ago. Wayne(rice)Burner 10" x 54" Atlas with QCGB Used for repair of classic motorcycles, and my 1965 JD400 TLB ------- Re: Atlas Gear Repair ??? Posted by: "Bruce Freeman" freemab222x~xxgmail.com Date: Fri Apr 15, 2011 5:52 am ((PDT)) Wayne: That's exactly the sort of repair I was thinking about, but I've never done it, only seen something like it. A friend of mine has a slip roller (for bending sheet metal) with enormous gears -- 2" wide, with teeth maybe 1/2" thick. Someone fixed some broken teeth by drllling three holes (for each tooth), screwing in bolts, and filing the bolts to match the gear contours. THAT gear has the mass. I take it you used a single brass pin so that you would have only the one hole in the gear face? Roughly what diameter pin did you use? I'm also thinking that you could make a partial "mold" in wax, using a good part of the gear as the pattern. Then you could situate the part with your brass pin in it within that mold and "cast" the JB Weld around that -- to minimize the work of filing. Bruce NJ ------- Re: Atlas Gear Repair ??? Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Fri Apr 15, 2011 9:12 am ((PDT)) havent heard of anyone successfully doing it .... ..if you have a torch & indexing/milling /or shaping capabilities, just cut a new gear...not that much more trouble ..... just started on gear sets for two different lathes tonight using 1/4 in tool bit ground to fit a gear used as a gage, as a fly cutter...9 in. barnes 4 1/2, & prentice bros 15 in....takes me abt one min /tooth on horiz mill after blank prep /mounting between centers. fwiw: plenty gears usually on ebay ... circa $10-15. best wishes docna8s ------- Re: Atlas Gear Repair ??? Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Fri Apr 15, 2011 9:32 am ((PDT)) > If they were iron gears I'd simply braze-fill and remachine > the needed teeth. I have done that and it works well. > Can these zamak gears be brazed with that fancy "aluminum" braze rod Those fancy aluminum brazing rods are almost identical to Zamac. Flows like water. It would be possible to clean the gear fully, make a mold out of steel (clamp steel on sides, and weld using the rods. You will make a mess and probably melt 5-6 teeth. Fill up let cool slow (usually fan the torch farther and farther away), them re-cut the messed up teeth. Scott G. Henion Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 ------- Re: Atlas Gear Repair ??? Posted by: "Rexarino" rexarinox~xxgmail.com Date: Fri Apr 15, 2011 10:47 am ((PDT)) Somewhere in cyberland there was a website where a fellow took thin metal, slightly stronger than aluminum foil, and formed it by squeezing it between two meshed gears with appropriate clearance. He used that tooth form and a pin, as Wayne suggested, to cast a new tooth. I would use Devcon aluminum putty (the professional stuff in the Holy Cow $$$ priced pint cans), but JB Weld should work. Coat the form with wax, Carnubua (sp?) wax, or Vaseline so the Devcon/JB weld doesn't stick to it. The times I tried to braze zinc alloy castings with the fancy rod, the base casting melted away faster than I could repair it. I've still got part of a stick of the stuff from the 60's; it works on aluminum, but I've had horrible results on zinc alloys. Rex ------- Re: Atlas Gear Repair ??? Posted by: "none" garybauer46x~xxyahoo.com Date: Fri Apr 15, 2011 2:24 pm ((PDT)) Thanks for the input fellows. Neat idea to mold repairs in-place. I wonder if this approach could also work for restoring trashed threading split nuts? Gary ------- Re: Atlas Gear Repair ??? Posted by: "Bruce Freeman" freemab222x~xxgmail.com Date: Fri Apr 15, 2011 4:22 pm ((PDT)) Why not? But the lead screw might be the better "mold" for that. It would be like pouring babbit. Bruce NJ ------- Re: Atlas Gear Repair ??? Posted by: "James Irwin" jirwin1x~xxaustin.rr.com Date: Fri Apr 15, 2011 4:31 pm ((PDT)) Methinks the longitudinal keyway might be a problem. Jim I ------- Re: Atlas Gear Repair ??? Posted by: "Bruce Freeman" freemab222x~xxgmail.com Date: Fri Apr 15, 2011 9:35 pm ((PDT)) Why? These are half-nuts. Pour them half at a time and the problem is simpler! Keep the keyway up while pouring. ------- Re: Atlas Gear Repair ??? Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Sat Apr 16, 2011 10:41 am ((PDT)) The threads have to align so both halves will close on the thread at the same time. Making a little aligning fixture out of sheet metal would keep the halves aligned. I think if you had both halves laying flat (to the sides) and the keyway straight up with a piece of square stock laying in the key, it would work pretty well. Jon ------- Re: Atlas Gear Repair ??? Posted by: "Rexarino" rexarinox~xxgmail.com Date: Sat Apr 16, 2011 1:21 am ((PDT)) Remember to offset the second one half a thread width. ------- Re: Atlas Gear Repair ??? Posted by: "Rexarino" rexarinox~xxgmail.com Date: Fri Apr 15, 2011 8:45 pm ((PDT)) I should mention a bit more procedure that will help with a high quality cast. Mix thoroughly, but carefully; by that, I mean attempt to not entrain air in the two part mix. I use a slow moving toothpick held vertically on small amounts, a slow vertical stir seems a little better at not mixing in air. If you have a vacuum pump, you can get rid of entrained air by vacuuming to around 26 inches of vacuum, IIRC. Note that the mix will expand to many times its size in a vacuum until all the air has popped out, so use a container 10 times the size of the mix. It's tricky getting the stuff in the mold to fill from the bottom up, and not capture bubbles while pouring into a small cavity. A syringe helps, as does vibrating the mold. I've resorted to pouring the epoxy down a rod to get it into a small space; sometimes that works. Rex ------- Re: Atlas Gear Repair ??? Posted by: "toro1554x~xxbellsouth.net" toro1554x~xxbellsouth.net Date: Sun Apr 17, 2011 8:05 am ((PDT)) If you have an electrical scriber, put the cup full of epoxy on top of it. Press it down on a piece of steel and turn it on. The vibration will make the bubbles rise to the top and dissapear. Fred ------- Re: Atlas Gear Repair ??? Posted by: "Keith Mc" actix~xxPROVIDE.NET Date: Sun Apr 17, 2011 5:58 pm ((PDT)) An alternative is to fab up a "DIY air powered ball vibrator" like a lot of the Epoxy-Granite people use. It's essentially a box you clamp to the frame you wish to shake. It has a circular ball bearing race inside of it for a single, massive ball bearing inside. Air spins the single ball in the race, causing a LOT of vibration. (There are NO shaft bearings to wear out, when compared to an offset weight attached to a motor shaft. :-) Google "Air Powered Ball Vibrator" to see a few commercial versions of it. Many guys have made their own, by cutting a large diameter blind hole in a middle of the face of a big block of metal, to act as the ball race. Drill/tap an 1/8" or 1/4" NPT hole for an air fitting pointed along the tangent of the inner perimeter, to let air spin a big ball bearing dropped inside. Cover the hole by bolting on a flat plate that has an air escape hole drilled in its center. Drill four mounting bolt holes around the perimeter (that don't intersect the ball race pocket :-), to allow you to bolt the block to whatever you'd like to shake. You can scale this to any size you'd like for the amount of shaking you desire. The depth of the hole should just be SLIGHTLY larger than the ball's diameter. (Use a BIG steel ball bearing. The ball's mass and the race diameter both highly affect the shaking power and shake frequency, respectively.) Now add a little compressed air with a regulator to control flow, and it quickly shakes the bejesus out of whatever it's clamped to. Advantages: The shaking device lasts nearly forever. (If the race is hardened, then there's practically nothing really to wear out. But why bother, for the occasional use?) The vibration method also causes a temporary "reduction of viscosity" effect, which quickly allows the bubbles to rise and escape, without needing the extra volume a "vacuum pull" method requires. Keith Mc. ------- Re: Atlas Gear Repair ??? Posted by: "jo barden" jobarden422x~xxmsn.com Date: Sat Apr 16, 2011 11:29 am ((PDT)) When I was repairing my half nuts I brazed up the threads and got a new ACME tap from Tracy tools in Devon who are very good by the way and just clamped the half nuts together and retaped. OK I now have a ACME tap 3/4" if I remember correctly but may come in useful sometime? I am a terrible tool hoarder anyway. Jon G6UWK ------- Re: Atlas Gear Repair ??? Posted by: "James Irwin" jirwin1x~xxaustin.rr.com Date: Sat Apr 16, 2011 12:02 pm ((PDT)) I suspect a good reclaim rework of a worn pair of half-nuts could be done by cleaning the old halves and leadscrew completely, waxing the leadscrew (as mold release), then closing the nuts onto the screw around some steel filled epoxy like JB Weld or Acraglass gel with steel filler to apply new material to fill in the gaps. Might not last too long, but could be a quick way to get back into making chips while awaiting new parts. Jim I ------- Gear Cutters [atlas_craftsman] Posted by: "anthrhodesx~xxaol.com" Date: Fri Apr 15, 2011 9:29 pm ((PDT)) I'm interested in acquiring several B&S-style gear cutters. 24 DP, 14-1/2 degree pressure angle Cutter #7, for 14 thru 16 teeth Cutter #6, for 17 thru 20 teeth Cutter #8, for 12 and 13 teeth Prefer smallest cutter OD and smallest bore for cutter arbor. I know that at one time these were available at substantially smaller than 1-3/4" and 7/8" respectively. Need to cut near to a shoulder. Might also be interested in 16 DP, 14-1/2 degree, same tooth counts. Must be DP, must be 14-1/2 degree pressure angle, to match existing gears with which they must be able to mesh. Alternative option is hobs, again smallest diameter and same specs listed above. Even interested in gear shaper cutters ala Fellows gear shaper (can be generic, Fellows not required). Anybody have any they're willing to let go of? Any leads to used or new sources? Of course there are budgetary considerations but if you have any info please send it. Anthony Berkeley, Calif. ------- Re: Gear Cutters Posted by: "Bruce Freeman" freemab222x~xxgmail.com Date: Fri Apr 15, 2011 9:37 pm ((PDT)) For what it's worth, these videos are interesting: http://www.youtube.com/user/Hobbynut [There are several videos in this series, so use links at youtube to find all of them made by Hobbynut.] ------- NOTE TO FILE: I checked out the video Bruce suggested and found it was just one of many videos made by Hobbynut on youtube (Shorty Leatherwood) with web address: Shortyleatherwoodx~xxyahoo.com and home site: www.leatherwoodplayground.com To save you a bit of time, I have posted the links here (in order) of a series Shorty made about making gears on a Sherline lathe and mill. Don't be put off by the "CNC" in the title. Every gear can be done on manual machines but will just take a bit more time. And you can do this on any make of metal lathe and mill (or lathe with milling attachment). These videos are an excellent teaching aid. And lots of tips and tricks along the way that will help you on other machining projests. Sherline CNC Gear Cutting Part 1 http://www.youtube.com/watch?v=MItgd-faHFw&feature=related Sherline CNC Gear Cutting Part 2 http://www.youtube.com/watch?v=vQGAK06JLQg&feature=related Sherline CNC Gear Cutting Part 3 http://www.youtube.com/watch?v=rBMRJ_K14IA&NR=1 Sherline CNC Gear Cutting Part 4 http://www.youtube.com/watch?v=7ETcZLJrWXE&feature=related Sherline CNC Gear Cutting Part 5 http://www.youtube.com/watch?v=62ymeJ0l9VM&feature=related And here is his excellent series on making homemade hobs. These things were always a bit of a mystery to me as I have never seen one in person, and book explanations were less than clear. Now they make sense. Thanks! Home made Gear cutting Hobs on my Sherline (part 1) http://www.youtube.com/watch?v=nMS2un-kbg0 Home made Gear cutting Hobs part2 http://www.youtube.com/watch?v=ykSOOXww0U0 Using W1 water hardening drill rod for the hob. Home made Gear cutting Hobs part3 http://www.youtube.com/watch?v=UqnqswBl6HA Home made Gear cutting Hobs part4 http://www.youtube.com/watch?v=8UBxNPbg0ls Home made gear cutting hobs part 5 http://www.youtube.com/watch?v=9bfJ_ARfP4I Home made gear cutting hobs part 6 http://www.youtube.com/watch?v=NebcXM-nZk4 Home made gear cutting hobs Conclusion http://www.youtube.com/watch?v=WCUO-JkdxAo And a quick update for this last hob series. Hob vid Correction http://www.youtube.com/watch?v=nFrc90Nzmio&feature=related ------- Re: Gear Cutters Posted by: "William Abernathy" williamx~xxinch.com Date: Fri Apr 15, 2011 11:07 pm ((PDT)) MSC carries these cutters, but they are not cheap. William Abernathy Berkeley, CA http://yourwritereditor.com ------- Re: Gear Cutters Posted by: "toolmaker48" toolmaker48x~xxyahoo.com Date: Fri Apr 15, 2011 11:26 pm ((PDT)) Hi. Your best bet is Ash Gear and Supply. They're probably the biggest in the U.S. They sell new and used. They have a web site. Robert ------- Re: Gear Cutters Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Sat Apr 16, 2011 6:36 pm ((PDT)) Art ...FWIW are you familiar w/ john stevenson's posts on making 4 toothed cylindrical gear cutters using double drill rod buttons spaced/angled for various tooth numbers, used as form tools.....then offset in the chuck to back off, so repeated sharpening can be done as long as grinding is radial ...? original post was for 20 deg, but i copied subsequent one for 14 1/2 ...dont know if they are still available on line, but i may be able to dig out my copies & slo mail a copy of them if this is a viable option for you ..... ..WTtool, Victor machinery exchange, Travers, are circa $35 /cutter new options ....Polish & China 14 pitch cutters ... i have ordered in the past from them and they have been satisfactory ...i may be making a # 3 cutter from stevenson's drawngs if my fly cutters dont hold up for the 10 or so gears i need to cut in that range... FWIW ...previous experience in cutting & using lathe change gears cut w/ higher numbered cutters than spec, viz :.24 T cut w/ 17-20 cutter, (stud gear),has shown absolutely zero problems in my usage, probably due to the adjustable nature of the banjo ....realize this is anathema to "precision " machining, & may offend some sensibilities, but the proof is there., & only 8 cutters for all involute tooth gear shapes is already an approximation. ( 1/2 # cutters are available for REALLY picky people) ...truth is, the brits have cut full sets w/ a #3 cutter & ground them in, large against small, w/ grinding paste / increasingly closer centers.... but that IS a bit much !!! my fly cutters from lathe tool bits have worked satisfactorily on brazed tooth repairs & brass gears made for thread indexing attachments ...will see how they hold up for multiple cast iron gears best wishes docn8as ------- Re: Quick Change gear box. [atlas_craftsman] Posted by: "anthrhodesx~xxaol.com" Date: Mon Jan 2, 2012 8:54 pm ((PST)) In a message dated Mon Jan 2, 2012 10:36 am (PST), Paul writes: > Book One of "MetalWorking" Has a home built QC. gearbox in it. Village Press is the publisher/seller. The book is 251 pages of projects, tools, aids and just good info. < [NOTE TO FILE: As of this date Book One is out of print. You might want to think about acquiring the later books before they too sell out.] Paul and all, There are at least two articles on home-built gearboxes which were published in either Home Shop Machinist or Projects in Metal (more recently named Machinists Workshop), possibly one article in each. These are both specifically for the Atlas 6" lathe but could be redesigned to suit the Atlas 10" or 12" lathes, possibly even the 9" lathe. The earlier of the articles was by Eugene Toscano who had written an earlier shorter version of the article which was published in Popular Machining (?). It's a good article starting out with a very good description of how a Quick Change Gearbox functions, including all the math calculations of how you cut different threads from one leadscrew. This design is more similar in principle to a South Bend gearbox than to Atlas' version. Nothing wrong with that. (PS If anybody can supply scans of the Popular Machining article I would appreciate receiving them, I had them at one time but lost them in a computer crash.) The second gearbox was written by Pettit (I think). It has a chain drive as part of the end gearing. I don't remember the details of this one although I've always thought that the chain drive created issues which would reduce the possibility to re-gear the end train for non-standard threads not included in the setup as designed. I have previously stated that the best article in my opinion for a home-built QCGB is the one by George Yadon, published in the July through December 1991 issues of Modeltec, again for the Atlas 6", and again could be re-engineered to suit any of the larger Atlas lathes. There is one more QCGB build article to suit the Atlas lathe, this time for the 10". This is a 4 page article in the October 1946 issue of Mechanix Illustrated, pages 108 through 111. A bit unconventional in that the 5-position range divider section is placed above the 8-position pitch section which carries the cone of gears which are all Atlas change gears co-opted for the purpose. I think this one would also be difficult to re-gear for alternative threads but, for fitting to the Atlas 10" lathe, it's the correct size to begin with. For the 12" lathe you might need to make small changes in the elements which take the drive from the 5-position section to the 8-position section but that should be pretty straight forward. Several designs for gearboxes to suit the Myford lathes are not suitable, in my opinion. There is also an article on line for a QC gearbox for the Asian 7-inch lathes, a pretty minimal effort. Anybody who has the James Early files should be able to find it in there. And there is an article on the Sherline site on a similar unit for that lathe, same objections. I don't know of any build articles other than the ones I've mentioned above, if anybody can refer me to such I'd be interested. Anthony Berkeley, Calif. ------- Lathe gear making [Metal_Shapers] Posted by: "Kris" klcastlex~xxgt.rr.com Date: Thu Aug 16, 2012 5:06 pm ((PDT)) Probably a stupid question but here goes anyway. I have a Harrison M250 I want to make gears for to change my threading capabilities. I also have an Ellis dividing head to help do the job. Can a shaper do this job or would a horizontal shaper be needed? I have a combo vertical/horizongtal Rockwell mill that does not have the outside arbor support option. Thanks for any input, KLC ------- Re: Lathe gear making Posted by: "JR Williams" jrwillmsx~xxhal-pc.org Date: Thu Aug 16, 2012 5:20 pm ((PDT)) You do not need an outside support for the arbor. I have made gears by manually grinding a single high speed tool bit to the tooth form and taking my time with the mill and dividing head. Another option is to buy a correct cutter. The shaper will work if you have a suitable indexing system, small dividing head or index head, that will mount on the shaper. ------- Re: Lathe gear making Posted by: "Bob Paulsen" bobx~xxphotoeyeview.com Date: Thu Aug 16, 2012 9:05 pm ((PDT)) Kris, You can cut the gears on your shaper. One of the challenges will be to mount the Ellis dividing head on the shaper box. I have a 10" Lewis and I needed to add a bolt-on plate to the shaper box to have enough room for my Ellis dividing head. It is easy to lose rigidity doing this. You don't need a horizontal mill to cut your gears. You can use a fly cutter in the vertical head and cut the gear on the side assuming the gear diameter isn't so large that it doesn't permit this. The cutter bit in the fly cutter would be ground to the gear tooth profile just as it would be for the shaper. After all this, I prefer to cut the gears on my mill. I start by using a ball nose end mill that matches the root of the gear teeth and follow with a profiled cutter. There is then less material to remove with the cutter bit and makes the cutter bit a little easier to grind. Bob ------- Re: Lathe gear making Posted by: "alan lapp" alanbataarx~xxyahoo.com Date: Thu Aug 16, 2012 11:03 pm ((PDT)) If you can cut a thread on a lathe, can cut slots on a mill, and can heat-treat tool steel, you can produce your own gear hob which you will use in the mill. The helical hob is always driven, and the gear blank is held in a fixture that allows it to turn freely. The hob can be used to cut gears of any diameter of the same pressure angle and pitch. You still need your dividing head to "gash" the gear blank, but once it is gashed, the helix of the hob will engage and drive the gear. It's a pretty straightforward process. The math of figuring out the blank diameter to suit the number of teeth is about the hardest bit. The Little Machine Shop used to carry a video by José Rodriguez that will walk you through the process. Here's the first hit I found: http://www.cartertools.com/vcr.html a ------- Re: Custom Gear [taigtools] Posted by: "Chuck Rice" Chuckx~xxWildRice.com Date: Sat Oct 13, 2012 8:36 pm ((PDT)) On 10/13/2012 11:19 PM, Patrick wrote: > Does anyone know where I can get a custom gear made? I am trying to repair a 1930s Model M-80 Hobart Mixer ("dough machine") for a friend. The small main drive gear failed, and my friend found someone to make the gear, but it failed after about 5 months. The replacement gear was made from aluminum, and I just don't think that was a good choice. The original (or at least most previous) gear was made from a fiber reinforced plastic of some sort, possibly nylon or phenolic. I have been advised by three experienced machinists that the new gear should be steel. It is possible to get the gear from Hobart, but they job it out to a custom shop and that shop will only make the gear set, which includes the small drive gear and the large matching gear (about 12" or so in diameter) AND they will only sell 2 sets at a time. The cost is around $1800. I am wondering if anyone on this list knows of a good custom gear cutter that would make just the one small gear. Thanks for any help! < Some of the members of the Home Metal Shop Club in Houston, TX sometimes do small job like this. Visit the web site at: http://www.homemetalshopclub.org There are also some great metalworking articles and videos in their archives. Chuck ------- Re: Custom Gear Posted by: "Stan Stocker" skstockerx~xxcomcast.net Date: Sun Oct 14, 2012 7:01 am ((PDT)) Hi Patrick, While any general machine shop could make the gear for you, they may not want to. A hobby guy with a good shop is probably a good bet as well, just has to be someone who actually has made gears rather than just read and talked about it a lot :-) Of greater concern is that fact that a new gear failed in only five months. Was the gear just "worn out", did it strip teeth, how did it fail? Aluminum isn't often the best material for gears, but there may be damage to one or more teeth on the larger gear too, causing failure. Could also be some bearing issues causing the teeth to get out of line. Making a part that fails stronger can sometimes be a good idea, sometimes it just makes a more expensive part fail instead. The original 1930's material you describe sounds very much like "Micarta", a fiber/linen/fiberglass/whatever was called for filled phenolic resin material. The material is still available, I have some sheets and squares here that I keep handy when restoring vintage electrical clocks. Depending upon the material used for the 12 inch gear and the lubrication available steel could be a good choice, or it could be lousy. I'd rather break a fiber / aluminum small gear than rip the teeth off a 12 inch specialized gear in a jam any day. If you have the patience, you could make a new micarta gear yourself using just a fine blade in a coping saw. Scribe the outline from the remains of the original gear, aligning as needed to get a good tooth profile. Fine sand to finish. Not elegant, but an affordable alternative. If there is a set screw securing the gear, it's probably got an insert in the gear. You can use a helicoil to get the thread strength you need. Micarta can put some nasty (health dangerous, not just irksome) dust in the air, I use a shop vac with a HEPA filter and run the exhaust hose out a window when I have to machine it. You may find this thread an interesting read, it wanders around a bit but discusses micarta and other non metallic gearing fabrication and sources/applications. http://www.eng-tips.com/viewthread.cfm?qid=227641 Norplex makes micarta gears and such today, drawings and specs are online. Take care, Stan Stocker ------- Re: Custom Gear Posted by: "Ron Thompson" ronx~xxourcadguy.com Date: Sun Oct 14, 2012 7:38 am ((PDT)) I see no mention of a photo or gear type. Spur gears aren't too difficult, but other types can be a bear. Ron Thompson On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA Think, Draw, Print. 3D printers ROCK! http://www.plansandprojects.com/My%20Machines/PrusaMendel2012-1/ http://www.plansandprojects.com My hobby pages are here: http://www.plansandprojects.com/My%20Machines/ Visit the castinghobby FAQ: http://castinghobbyfaq.bareboogerhost.com/ ------- Re: Custom Gear Posted by: "Gaston Gagnon" gaston.gagnonx~xxvideotron.ca Date: Sun Oct 14, 2012 8:23 am ((PDT)) Hi guys In case you did not know of this little great program made by Art Fenerty [ The Mach3 guy :o) ] can be helpful to design gears. www.gearotic.com ------- Re: Custom Gear Posted by: "Ron Thompson" ronx~xxourcadguy.com Date: Sun Oct 14, 2012 11:22 am ((PDT)) On 10/14/2012 1:57 PM, george wrote: > how about casting the gear in brass, bronze or other material. Most cast gears aren't very accurate. You could cast the blank and then cut the bore and teeth. Ron Thompson ------- Re: Custom Gear Posted by: "DavidH" dsh1001x~xxgmail.com Date: Sun Oct 14, 2012 1:10 pm ((PDT)) If you want to be sure it is made right then try "Lawler Gear" in Lee's Summit, MO. http://www.lawlergear.com I don't know if he has a minimum order price and either way it will probably not be cheap, but it will be done right. If you are in the area, you should ask for a look at his shop as well. He has some beautifully restored antique machines that are more than display pieces. They are used to make gears (of course). There was a fiber gear in there for a reason, so you should probably replace it with the same material or at least a bronze gear as suggested earlier. My guess is that the point of a fiber gear was to eliminate as much grease as possible since it is a food service machine but it may also require a shock resistant material due to the gear arrangement. I, personally, would not use steel but the other side of that coin is that even if the new steel gear eats the old 12" gear, then the whole gear set could be ordered. ------- Re: Custom Gear Posted by: "chuck_rh_mi" cgstuartx~xxgmail.com Date: Mon Oct 15, 2012 5:50 am ((PDT)) Another potential source is KA-Wood Gear, if Michigan is closer than Missouri. We've used them for work stuff, but I know they also do custom and they are very good to work with. I doubt it would be exceptionally cheap, but if they already have a hob that can be used, they would be quite competitive. Their web site is http://www.kawoodgear.com/index.html. Good luck! ------- Re: Custom Gear Posted by: "Ken" kvaughanx~xxacsalaska.net Date: Tue Oct 16, 2012 6:36 am ((PDT)) Some years back I repaired several mixers made by Hobart. They all had a gear that failed -- the same gear -- because it was designed to be the failure point when the abuse to the mixer needed to end for a while. I suspect the failing gear has some relationship to either a need to closely exanine the mating gears for burrs and such OR talk to the operators about the abuse levels they are pushing that old timer to handle. You can fix the gear and move the failure point. ------- Re: Custom Gear Posted by: "gareth evans" headstone_255x~xxyahoo.co.uk Date: Tue Oct 16, 2012 7:59 am ((PDT)) Over here in Britland, there are a number of individuals who would make such gears for the asking, but I understand that in Yankland that you tend to buy all your bits rather than make them from first principles. (Currently putting together a gear hobber using a Taig headstock, not the rest of the lathe, as the workpiece spindle -- using stepper motor onto 80-tooth change gear.) ------- Re: Craftsman 10121400 Gears [atlas618lathe] Posted by: "glenntober" glenntx~xxpalmnet.net Date: Wed Oct 17, 2012 11:01 am ((PDT)) "alvinjonhson72" wrote: > That's interesting. How would steel gears get along with (mesh) the > older original alloy gears. Would the steel eat up the zemac gears? IMHO, dimensionally compatible gears do not "eat each other up". Atlas thread gears should always be positioned with 'paper thin' clearances between gears since tight meshing serves no purpose when screw cutting in one direction. Under undue stress, the weaker gear might fail first. If something like a big metal chip gets ingested, then the softer gear may take all the damage but I do not see any real issues with either of these cases. Bronze or brass would, however, be a better choice if you are making the gear yourself. ------- Re: New file uploaded to atlas_craftsman [atlas_craftsman] Posted by: "anthrhodesx~xxaol.com" Date: Sat Dec 22, 2012 6:10 pm ((PST)) Having accessed this metric chart it should be pointed out that it is for early lathes which did NOT have a reversing mechanism in the gear train. All trains start with a 32 on the spindle and at least some of the gear trains use a 96 tooth gear. Actually it's good to have this chart available, both for those who have lathes with the above mentioned characteristics and for people who are interested in the entire concept of gear trains and how you set up trains to result in particular multiplication or reduction ratios. Anthony Berkeley, Calif. ------- Re: New file uploaded to atlas_craftsman Posted by: "wa5cabx~xxcs.com" Date: Sat Dec 22, 2012 11:05 pm ((PST)) Notice: The early 12" Metric gear chart was cleaned up, size reduced 95% and relocated into: Files >Tables, Charts &Formulas Robert D. Moderator ------- NOTE TO FILE: There is an article in the Solder text file here about repairing some gear teeth. The article starts Jan 5, 2013 and is called Re: Backgears - repairable? no oil nipple? [myfordlathes] In case you are wondering, the generic term soldering does include high temperature silver soldering, which also has been referred to as brazing. High temperature brazing using silver or bronze or alloy filler is more like soldering than welding. In metal repairs, the method is chosen to suit the materials involved and the strength required. ------- Re: seized gear bushing [atlas_craftsman] Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Fri Jan 18, 2013 5:18 pm ((PST)) On 1/18/2013 8:11 PM, rjsbinders wrote: > HI has any found a safe way of removing the bushes that have become > seized inside the change gears, without breaking the fragile gears. > Richard Put a socket larger than the ears on the bushes in a vice. Place gear over it. Use a socket just smaller then the gear inside diameter and tap it through with a soft hammer (block of wood works). I usually just open the vice just wider than the bushing and set the gear on it rather than find the correct socket; mine are usually not real tight, just more than you can do by hand. Scott G. Henion Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 ------- Rotating fixture to produce helical gears [Metal_Shapers] Posted by: "john" John.Burridgex~xxfsmail.net Date: Wed Feb 20, 2013 2:28 am ((PST)) Hi to all, Has anyone seen a rotating fixture from the past so that you can manufacture helical gears on a shaper or planer. I cam across an old book which had this jig/fixture of about 1920 and it showed examples of finished gears which look good. Regards John Burridge ------- Re: Rotating fixture to produce helical gears Posted by: "Richard Wilson" richardpwilson61x~xxyahoo.co.uk Date: Wed Feb 20, 2013 6:13 am ((PST)) John, I'm fascinated. Does this book have any diagrams of the fixture? Richard ------- Re: Rotating fixture to produce helical gears Posted by: "samuel" visicoachx~xxcomcast.net Date: Wed Feb 20, 2013 6:14 am ((PST)) That's kind of hard to find and if so it's big bucks so I made my own. ------- Re: Rotating fixture to produce helical gears Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Wed Feb 20, 2013 9:02 am ((PST)) Gould & Eberhardt in the 20's had a fixture in their ads, also in Cope's book on shapers.......never seen the real thing .....utilized an incline, & an arm attached to the work slides up the incline as the shaper ram comes forward taking a cut, the gear which is on centers rotates. wud not take much to construct one if index centers are available ....same idea was used on planers for SLO helices & can be done on a mill also... the incline is fixed & the table moves w/ the gear ( shaft )rotating, as the arm attached to the gear ( shaft ) rides up the incline while the cut is made......slow twists for rifling guides were made this way in the bygones. best wishes doc ------- Re: Rotating fixture to produce helical gears Posted by: "alan lapp" alanbataarx~xxyahoo.com Date: Wed Feb 20, 2013 12:05 pm ((PST)) I normally associate helical gear cutting with bigger horizontal mills. The smaller mills didn't have an accessory output (think PTO shaft) for the dividing head. The accessory output has a change gear arrangement to set the angle of the helix, much like a lathe uses change gears to select thread pitches (which is also, technically, an angle of a helix). a ------- Re: Rotating fixture to produce helical gears Posted by: "john" John.Burridgex~xxfsmail.net Date: Sat Mar 2, 2013 5:10 am ((PST)) Hi to all interested in cutting bevel gears on a shaper or planer. Sorry I haven't added the link to machining bevel gear on a shaper or planer but have been busy getting out a racing car for the coming season. The links are:-American Machinist May 9 1885. http://www.google.com/patents?id=n6diAAAAEBAJ&printsec=abstract&zo om=4#v=onepage&q&f=false http://www.google.com/patents/about?id=n6diAAAAEBAJ&dq=294844 I'm sure a fixture could be made to cut bevel gears as it has been done before. Regards John Burridge ------- Re: Rotating fixture to produce helical gears Posted by: "oldstudentmsgt" wmrmeyersx~xxsbcglobal.net Date: Sun Mar 3, 2013 8:17 am ((PST)) Try this link: http://books.google.com/books?id=qBBWAAAAMAAJ&dq=helical%20gear&pg=R A9-PA24#v=onepage&q=helical%20gear&f=false It's an ICS book on Shaper & slotter, milling, and gear cutting, with pictures of a helical gear cutting fixture. Start at page 24, Helical Gears. HTH! Bill in OKC ------- Re: Needing gear info confirmation. [atlas_craftsman] Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Fri Mar 1, 2013 12:12 pm ((PST)) Thu, Feb 28, 2013, zman0690 wrote: > The 101.28990 Craftsman 12x36 I recently acquired is going to need several new gears due to wear which has caused the teeth to become mushroomed, pointed and have excessive clearance. I need to confirm that the DP is 16 and the PA is 14.5 for all the gears on this lathe. I have read contradictory information regarding this. Can someone please confirm so I can go ahead and invest in the involute cutters needed. Thanks! Josh < 16 pitch & 14 1/2 PA .....travers had the chepest gear cutters when last i bought, around $35 ea...you will need 5 cutters to PROPERLY cover 20 -64 T gears ...expensive ....used gears used to be abt $10 ea...i may have a few around & maybe a new one or two ....they are ususally on ebay ...properly maintained zamak gears have been on my 12x36 for 40 yrs & are just fine ...same for my 6x18 last 50 years. you can also grind a fly cutter from a lathe tool bit using a gear tooth as a gage /template ...have done that a few times. you can also make your own 4 tooth carbon steel gear cutter if you are really hard headed...relieving by offsetting in a 4 jaw. ALSO browning & others have 16 pitch gears available commercially ...you may have to bush or keyway cut .....smaller gears used to be abt a dollar a tooth ....cast iron or steel. unless you just WANT to make gears (& that's fine), .... over the years i have cut abt a dozen for obsolete 14 pitch,, several gears for thread dials, & i have the blanks now prepared for another 30 or so .16 P.... bringing antique lathes back to life. best wishes doc ------- Pick O Matic change gears. [atlas_craftsman] Posted by: "dlclark66" danx~xxdcdetec.com Date: Tue May 14, 2013 6:21 am ((PDT)) I finally got around to cutting some threads with my Atlas Pick O Matic and took inventory of my change gears. I was missing three gears one of which is the one I needed for the threads I wanted to cut. Looking on EBay I couldn't find the right gear so I used my 3D printer attachment for my CNC table and printed one out of Taulman 645 nylon. I wasn't sure if it would hold up cutting threads but it worked perfectly and didn't show any signs of wear and tear after cutting the threads. If anyone else is having trouble finding missing gears and has a 3D printer available it's worth a try. Dan ------- Re: Pick O Matic change gears. Posted by: "dlclark66" danx~xxdcdetec.com Date: Tue May 14, 2013 10:08 am ((PDT)) I found a great article on drawing involute gears with Google Sketchup. I've already been drawing gears with this method and it works well for me. I was going to post a how to here but this is much better than I could possibly write. http://capolight.wordpress.com/2011/01/22/drawing-gears-in-sketchup/ There is a plug in for exporting SKP files to STL. The install files and instructions can be downloaded here. https://github.com/SketchUp/sketchup-stl/blob/master/README.md Once you have both plugins installed draw the gear needed and use the STL export to create a file suitable for 3D printing or export to another CAD program or your CAM program. Here's a link to the video of the gear being printed along with photos of the finished part. http://youtu.be/F7PF0dRgZS8 ------- Re: Pick O Matic change gears. Posted by: anthrhodesx~xxaol.com Date: Tue May 14, 2013 9:12 pm ((PDT)) Dan, Is the drawing program limited to conventional gears or can it draw profile shifted gears? I nave at least 2 projects in which I want gears that are over or undersize. As an example I want a 16 tooth 24 DP 14.5 PA change gear for an Atlas 6" lathe cut to the pitch diameter for a 20 tooth gear. Will the program draw such a gear and produce a file which can be used for printing such a gear? While it's not my preferred end process it might, at least, produce a gear to proof the concept and for trial purposes in a gear train on the lathe. Anthony Berkeley, Calif. ------- Modifying a gear -- or should I? [Metal_Shapers] Posted by: "Miket_NYC" mctaglierix~xxgmail.com Date: Sat Jul 27, 2013 6:19 am ((PDT)) I mentioned previously that the South Bend shaper I just bought has a gear missing -- the small one on the shaft from the motor that drives a huge bull gear. Apparently the little gear is 16 tooth, and the seller has found a 16-tooth gear that he's sending it to me. But the one he's sending isn't THE 16-tooth gear. It's a different gear he found in his (very full) garage of machine tools for sale. He says it's the right tooth size, but it's also 1/2" wide, although the bull gear it will drive is 3/4" wide. In addition, the gear he's sending has teeth along its whole length, but the original gear had a section on one side without teeth, and that was where the gear was pinned to the shaft. So I'm not sure whether I should use the gear the seller is sending, or try to find/make something better. If I use it, I'll have to fasten a piece of metal rod beside it where the pin will go, and I was planning to silver-solder that in place, which I think (hope?) will be strong enough. But even if I do that right and align the gear perfectly, it will still be only 2/3 as wide as the gear it mates with, so it will be the weak point in the system and may also cause uneven wear on the bull gear. South Bend designed this shaper for the small shop/advanced-amateur market, but they presumably made it as strong as that they thought they needed to do, and if they thought they could get away with making it weaker they could have done that. So making one single part 2/3 as strong as the rest of the machine seems like asking for trouble. The alternative would be to look online for a gear 3/4" wide. So far, I haven't found one among the stock gears of the various firms -- just 1/2" gears for about $25. It's possible I could have a custom gear made, but I don't want to imagine what that would cost. Or I could make a gear myself, but that's something I haven't done yet, and I'm not too keen about doing something for the first time when I'm making a critical part for a machine. Of course, there's always option #3 -- put the shaper together with the gear I've got, but keep looking for something better. But I have so many projects going at once that I'd rather get a job done right so I won't have to think about it again. So what should I do? Comments would be appreciated. Mike Taglieri ------- Re: Modifying a gear -- or should I? Posted by: "Kenny" ksergeantx~xxmac.com Date: Sat Jul 27, 2013 8:58 am ((PDT)) Mike, You might consider stacking two of the 1/2" thick stock gears. Drill and pin them together, turn the teeth off half of one gear and drill the turned section for the cross pin that secures it to the shaft. The pins will serve to align the gears as well as hold them together if properly designed and assembled. When complete you will have an assembly that physically matches the original SB gear dimensionally. Strength could match, or exceed, that of the original gear, depending on materials and heat treatment of the gears, and, proper material, heat treatment, sufficient number and size of pins. Press fit or tightly stake the assembly pins, to further limit rotation between the gears. Properly done, there would be minimal shearing forces on the pins holding the two gears together. Ken ------- Re: Modifying a gear -- or should I? Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sun Jul 28, 2013 6:48 am ((PDT)) Mike, If you have a rotary table with index plates you may be able to make your own. I've done it many times. If you want to do it on the cheap you can do it with a fly cutter and HSS tool. Assuming you have the gear the dealer is sending you to guide the form you can grind a form tool using a 10X loupe and strong light to ensure that your form is correct. Not everyone can grind tools with the necessary relief by hand, I think it's like singing or painting, an art perhaps. Anyway, I've ground the HSS many times holding the tool up to a light with the loupe and original gear to check the form tool for correctness. It's been said that a strong light can reveal much less than a ten thousandths of an inch of irregularity, and I believe it. After that it's just a matter of correct feeds and feeds in the mill. It's noisy, sounds all wrong, but if done carefully in stages with an earlier tool in a roughing pass you can end up with a gear to be proud of, and that will wear well. All the above supposes a spur gear, which I believe my SB7 has. I'd never try that with a helical gear like the Ammco has, that's way too much work when gear companies do such a great job relatively cheaply. Me, I'd give a call to a gear company, life's too short to waste doing that. (Grin) Plus, as soon as you go through that you'll find the gear. I assume you patiently watch ebay, and if you know the DP and tooth count (Which you do) you can see if two gears come up on ebay and silver solder them together, then turn and face as needed for your B boss and pin hole. Thanks, Glen ------- Re: Modifying a gear -- or should I? Posted by: "Rex Burkheimer" burkheimerx~xxgmail.com Date: Tue Jul 30, 2013 8:00 am ((PDT)) The gear companies make a gear "stick" that would work for you. The last one I saw was about the size you need, and maybe 6" long. You just turn that boss on the end and then part it off at your 3/4" gear width. I'd give it a little more time to get the right gear and fix it right. Rex B - DFW ------- Atlas 10" change gears [atlas_craftsman] Posted by: "dlclark66" danx~xxdcdetec.com Date: Wed Sep 18, 2013 6:58 am ((PDT)) I was missing a few change gears for my Atlas 10" Pic O Matic lathe so I decided to try to draw them out and print them with my 3D printer. I used Taulman3D.com 618 nylon for the material since it is kind of self lubricating and stronger than PLA for a gear application. It turned out so well that I created STL files for all of the change gears and printed them. I've placed these STL files on Thingiverse for anyone who might want to print their own gears. The Pic O Matic uses most of the standard 10" Atlas gears so there may be one there that you need. I hope someone finds them useful. You can find them here http://www.thingiverse.com/thing:143893 ------- Re: Atlas 10" change gears Posted by: anthrhodesx~xxaol.com Date: Thu Sep 19, 2013 7:43 pm ((PDT)) dlclark66 (???), downloaded the files out of curiosity. I don't have a 3D-printer nor a larger Atlas lathe so they aren't of any use to me but I'm curious about several things. You appear to have a 20 without keyways but no 20 with keyways. You have 24 tooth 20 PA, for what? You have another 24, what PA and with or without keyways? You have two 46s and two 48s, the significance of which I haven't sorted out. You have no 54. You do have 32, 36, 40, 44, 50, 52, 56, 60, and 64. There are other gears which would be useful, 21, 63, 37, and 47 are useful for inch-metric conversion, as is 34 combined with 36. 38 is useful for 19 TPI. Depending on how difficult it is to generate the files, it might be useful to include all numbers from 20 through 72 (80, 100, and 127 might be a stretch). How did you generate these files? Are they true involutes or circular approximations? How difficult would it be to do the same for 24 DP gears as used for the Atlas 6" lathe? Can you do gears with altered pitch diameters? I'm CCing a copy of this message directly to you, I'd be interested in some discussion off group. Anthony Berkeley, Calif. ------- Re: Atlas 10" change gears Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Fri Sep 20, 2013 7:27 pm ((PDT)) > You have two 46s 46 T is the "stndrd" gear for 11-1/2 tpi pipe thrds on many older loose change lathes ...used for IIRC 11/2 in & other pipe thrds....although i cut a 23 gear to use w/ compounding since i did not have a 4in disc of cast iron ......why two ? dunno .... best wishes doc ------- rookie gear cutting? [sherline] Posted by: ron_tenthoreyx~xxyahoo.ca Date: Thu Mar 6, 2014 8:41 am ((PST)) Want to cut gears! Bought cutters on Ebay. Understand the principles of setup from watching youtube vids, but if I cut a 1" gear and use 10deg as stops do I use 5 deg on a 2" gear to mesh properly? Math was not my best subject in school! Should have paid more attention to the trig prof. What if I want a 2:1 ratio to speed up the rotation? Really all I need is rotary stop points for each tooth> Thanks ------- Re: rookie gear cutting? Posted by: procterx~xxihug.co.nz kwstse Date: Thu Mar 6, 2014 10:47 am ((PST)) Hi, gear cutting is complicated, largely because it's been done for hundreds of years before there were rotary tables so people had to use more complicated methods. You're almost there except that the diameters you need to work with are the metal disc diameter minus half the height of the tooth twice. If for example you start with a 1" disk and cut teeth 0.1" deep then the effective diameter will be 1" - 0.05" - 0.05" = 0.90". Therefore your 2:1 gear needs to be 1.80" effective diameter or 1.8" + 0.05" + 0.05" = 1.90" diameter. Axle spacing becomes 0.9" + 1.8" / 2 = 1.35". If you were intending 1.5" spacing then you need to increase all dimensions proportionately. Greg.Procter, Hukerenui, New Zealand. ------- Re: rookie gear cutting? Posted by: "Hamilton Elliott" hamiltonx~xxmicroflex.ie Date: Thu Mar 6, 2014 11:08 am ((PST)) Hi ??, I would suggest that you have a look at www.gearotic.com as it will give you a lot of the math bits in a visual form. It has been written by the guy who wrote MACH3 and makes complicated quite simple. It's aimed at outputting to CNC but ignore the output and use it to do the calculations for you. Regards, Hamilton ------- Re: rookie gear cutting? Posted by: "Ken Condal" kencondalx~xxyahoo.com Date: Thu Mar 6, 2014 6:09 pm ((PST)) I agree with Hamilton. Gearotic does all the math for you and it’s easy to work with. You asked about a 2:1 gear ratio. If one gear has twice as many teeth as its mate, you have a 2:1 ratio. The smaller gear must turn twice to complete one turn of the larger gear. Ken ------- Loose Gear Storage [atlas618lathe] Posted by: "Gary Bauer" garybauer46x~xxyahoo.com Date: Mon Mar 10, 2014 1:37 pm ((PDT)) Hello Guys, A simple storage for your 618 loose gears can be a plastic 40 oz peanut butter jar. The empty jar is mounted inverted to a 4" square piece of wood by the lid. That base also features a 1/2" wood dowel through the center and out through the jar bottom (now top). The container resembles a bell jar. The wood dowel had to be sanded down to 1/2" as it was way out of spec from china (big surprise!). I painted the wood base and the dowel to preserve them in the shop environment. For larger gears of the 10 - 12" lathes I used a larger plastic peanut butter jar. Gary in AZ ------- Gear tooth cutting on a shaper [Metal_Shapers] Posted by: rocky_beechx~xxyahoo.com Date: Tue Apr 1, 2014 4:44 am ((PDT)) Gents, I would like to try my hand at cutting gear teeth on my 7" shaper. The gear will probably be about 3" in diameter with a 1/2" bore. I am wondering if anyone has any photos, descriptions or advice on holding the gear. I do have an Enco dividing head. Thanks in advance. Russell ------- Re: Gear tooth cutting on a shaper Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Apr 1, 2014 5:35 pm ((PDT)) ..FWIW ..to use a dividing head..& cut each tooth to depth. depending on pitch you may need to take several hundred cuts ..that is really the hard way .......several yrs ago i cut many 14 pitch gears on a small horizontal mill w/ ONE CUT PER TOOTH. ...w/ a single point tool & a rigid holder, i can take a .100 thou cut on my atlas ...w/a form tool like a gear cutter or a fly cutter ??????? maybe 10 thou ??? maybe 5 ???.. that's maybe 14 -28 cuts for a 14 pitch gear for one tooth ...you MAY be able to mount the idviding head on the table & have room, if not you can mount it on a slab & attach that to the tabel OR a 7 inch angle plate can be added to the end of the table (enco has free shpg & no minimum the next 3 days). i ordered one several years ago & never bolted it up ...i wud cut the keyway first & bolt the blank on a SHORT thick mandrel w/ a key. there is info around the net on using wires to rotate the blank incrementally as the ram moves (no dividing head), actually forming the teeth w/ either a fly cutter or a rack gear cutter (used for any number of teeth), but i have not done so ..i do know that one fellow, a retired doctor from the north west did make a gear this way successfully ....the method i think originated w/ the Brits model eingineering mag ...i may have copied the info years ago, but digging it out wud be a chore....if i still have it. hopefully some one has ready access to the info. best wishes doc PS ..i am pretty "muley ", but cutting a tooth individually one at a time on a shaper wud be the VERY LAST POSSIBILITY. ------- Re: Gear tooth cutting on a shaper Posted by: jhovelx~xxgmx.net joe_hovel Date: Wed Apr 2, 2014 3:37 pm ((PDT)) That is exactly what I did to repair the gear drive of a home-made electric quad for my grandson. Have a look here: http://www.woodworkforums.com/showthread.php?t=121056&p=1673648#po st1673648 Not sure if you can see the photos without being logged in, but I think so. The hardest part was grinding the gear GAP shaped cutter because the gear is helical. But I got close enough to end up with a very quiet gear train and little backlash. The quad is still in pretty wild regular use by Ned who is now 4 :) I cut each tooth to full depth by setting the table so the end of the tool adjustment was the final depth of cut and then just slowly would the tool down to the stop for each tooth gap. Because I had built an electronic divider for my rotary table, setting the position for each cut was not really tedious despite the 65 teeth. I'd certainly do it again without a second thought. Cheers, Joe ------- [gears for Atlas 618 6 inch lathe] stripped nylon gears [atlas618lathe] Posted by: rosslathex~xxyahoo.com Date: Mon Apr 28, 2014 10:14 pm ((PDT)) Lady Chatterley is now a stripper -- took off some teeth from the nylon tumbler gears of my 221200/3950 mk2 --I note in the parts book that the 20 and 24T gears are the same number that comes with the drive for the feed gear in the basic version without the extra change gears -- the drive gears are keywayed and the tumbler gears are nylon with no keyway. Any reason not to just use the zemac drive gears in place of the nylon? Any good source of the gears other than clausing? Anyone know of any for sale? Does this imply a diagnosis or is this a common occurrence? I was doing a 1 1/8 by 8 tpi external thread for an oliver spindle adapter -- Is this too big a dia even with light cuts in aluminum? Jim ------- Re: stripped nylon gears Posted by: ksierensx~xxmsn.com Date: Tue Apr 29, 2014 4:50 am ((PDT)) My Craftsman 101.21200 MK2 has zymac tumbler gears, I have heard of others with nylon gears and other than making the gear train quieter, I wondered why they were used. As for 1 1/8 being too big, I just finished boring out a 2 3/4" diameter steel bore, so I would say no, that is not too big ;) Kurt ------- Re: stripped nylon gears Posted by: migueldeservantesysaavedrax~xxyahoo.com Date: Tue Apr 29, 2014 5:43 am ((PDT)) Well I have to say that long before I have this lathe I have been collecting gears "That I actually happened to find out to fit perfectly in pitch and size for this lathe" they are "1/8 SCALE TRANSMISSION GEARS FOR RC OFF ROAD BUGGY" the kind that is gas, or Nitro powered! Also, to my total surprise, the gears that are used on the 2 mini lathes from harbor freight fit the needs of the atlas/craftsman lathes. Nevertheless the ones designed for the 1/8 ifmar racing are still gears and do a pretty god job and the possibilities of stripping them is very low! They are designed to be used on very stressful and abrasive environments and most of the really high end cars are the ones made of hardened steel. Like Serpent, Mugen, kyosho, etc! I have so many gears that I have been collecting for so many years, basically my goal was to build an automatic tranny for the ones that I use to race on NY, near the White stone bridge. So there, you have two different sources of gears that must likely will allow you to finish that project. ------- Re: stripped nylon gears Posted by: anthrhodesx~xxaol.com Date: Tue Apr 29, 2014 9:55 am ((PDT)) Jim, I suppose there's a minor drawback to having the keyways but I don't think it's a real issue. And zamac is what was used on all the early models of the 6" lathe. You can debate whether the nylon gears are just too weak or if they serve as a safety feature. Sources: Members of the group, referrals from members of the group, ebay for new or used. Boston and Browning used to be good sources but they don't seem to be interested in small gears. Same lack of interest for MSC and McMaster-Carr. 8 TPI is on the standard change gear chart so, presumably, Atlas thought that the lathe could do the job. It fits into the common practice of twice as coarse as the leadscrew pitch. They even list 7.5 TPI in the odd threads chart. Anthony Berkeley, Calif. ------- Re: stripped nylon gears Posted by: anthrhodesx~xxaol.com Date: Wed Apr 30, 2014 9:01 am ((PDT)) Miguel, The mini lathe gears are 1.0 module 20 PA, which is equal to 25.4 DP. The correct gears for the Atlas (or Craftsman) 6: lathes are 24 DP 14-1/2 PA. So the mini lathe gears are small by more than 5% and the wrong pressure angle. The small size and wrong pressure angle are not a drawback as long as you never mesh them with the standard gears. This means you should never mesh the metric gears with the 32 or 16 on the tumbler reverse, otherwise no problem. And as they often come in tooth counts which aren't readily available these days in 24 DP they can provide excellent opportunities for superior gear trains. Notably, gears with 25, 30, 35, 38, 45, 50, 55, and 60 teeth are readily available, also maybe 65, 70, 75, and 80 teeth. I hadn't thought much about this. I'll have to look into this myself, as long as the bore and keyways can be made to work on the Atlas 6". Anthony Berkeley, Calif. ------- Speaking of gears [sherline] Posted by: davidryx~xxosorail.com david_rygmyr Date: Fri Jul 11, 2014 9:32 am ((PDT)) Speaking of gears, I should mention our company because we make gears from scratch. Most of what we make is relatively small; our company services the model railroad industry and so we're definitely not as well known as say SDP-SI. That said, some do find us and we make gears for a few optics companies (telescopes and microscopes) and for some robotics programs at some universities. We're on the Sherline list because we own and use several Sherline mills and lathes, primarily for one-off work. Their small size is ideal for a lot of this, and as you can imagine most of what we do is collet work. Back to gears, your first step into our world might seem a bit odd because our gears are presented more as what's needed for XYZ company's 123 locomotive, versus a strict drill-down by numbers like you see on SDP-SI. However, everything we do ultimately boils down to a specific MOD or DP, tooth count, and then SG, WG, or RWG. Our process starts with a machine called a hobber and a stick of material (typically Celcon or brass) that we turn down to just over desired OD on a lathe and then put in the hobber. Then, and I'm simplifying here to try and keep this short, the hobber makes "a stick of licorice" to whatever DP/MOD SG/WG/RWG and tooth count we're going for. We have a library of these sticks, and then when we get a work order we take these sticks over to a turret lathe (Myford) where we make the bore, face, cut any shoulder needed, etc. We run batches of 50-100 gears at a time because ours is a niche market and we service everything from N scale to G scale. To wrap this up, we too can make gears; we have a whole line of 72DP gears. We also have polished steel worms, although those are mostly MOD because of the nature of model railroads (although we do carry 72DP.) Here's a link to part 4 of our catalog; scroll down to page 4-20 to jump over the model railroad-y lists and get into the more "regular" gear stuff: http://www.nwsl.com/uploads/chap4a_web_04-2014.pdf One other thin to mention is that some just buy hobbed sticks from us and then turn around and cut their own gears to whatever bore and face they need for their particular project. We used to offer custom work for individual gears but in this "recovering" economy that's hard to do. Here's one more link that might be useful; our gear request form. Just leave the model railroad-related fields blank and fill in what you can, mentioning in the comments that you're just looking for a particular gear. We often have a gear already in production (for a model RR) that might suit your needs: http://www.nwsl.com/Gear_Request_FORM.html Sorry for the long email but gears do come up on this list from time to time, and we might be an option for you if need be. Dave Rygmyr NorthWest Short Line (www.nwsl.com) ------- Cutting a stepped gear on the lathe [myfordlathes] Posted by: garthnx~xxpbt.co.za garthn444 Date: Sun Aug 10, 2014 12:37 pm ((PDT)) I am attempting to cut a new back gear out of aluminium. I've figured out how I can cut the teeth on the larger diameter - but how do I cut the smaller diameter with the minimal clearance available? Are these normally broached or cast, or done by some other method? ------- Re: Cutting a stepped gear on the lathe Posted by: garthnx~xxpbt.co.za garthn444 Date: Sun Aug 10, 2014 1:16 pm ((PDT)) My problem is that if I put a 1/8" depth cutter into a holder, the gap between the main diameter and the teeth on the small diameter (looking at the gear from the side) needs to be 1/8" + half of the holder diameter. If the holder diameter was 1/2", that makes the gap 3/8". The gap on an original gear is only 1/8". Making the holder run eccentric won't work. ------- Re: Cutting a stepped gear on the lathe Posted by: "Kevin" tadpolex~xxbtinternet.com klokenz Date: Sun Aug 10, 2014 1:45 pm ((PDT)) I'd be thinking about making the two gears separately, and joining them up once the teeth were finished. Of course, if you had a shaper.... There are industrial processes which involve a reciprocating cutter of one type or another, which don't have the clearance problems that you mention with a rotary cutter. Good luck, do keep us posted with how you get on. Kevin ------- Re: Cutting a stepped gear on the lathe Posted by: garthnx~xxpbt.co.za garthn444 Date: Sun Aug 10, 2014 2:01 pm ((PDT)) Yes, I thought too about two separate gears, screwed together. I don't really see why that wouldn't work. I've also been wondering about making the cutter somehow move in a non-circular motion, can't figure that out. What do you mean by a shaper? I'll post either way. I managed to cast an aluminium gear blank, after several attempts at casting, the quality seems to be there. Very little porosity is visible (I used a Mikrosal tablet, it is supposed to degas, clean and improve the density all in one go). Very cheap. Also good quality aluminium (from quality parts including a high performance Toyota piston). I didn't try to work out how to cut the teeth before casting ;) I was really trying to get the casting working first, if I revert to two gears, the blank will just be recast Garth ------- Re: Cutting a stepped gear on the lathe Posted by: "john baird" alexandra.leavingx~xxyahoo.co.uk Date: Sun Aug 10, 2014 2:49 pm ((PDT)) Mount the cutter in the toolpost, mount the gear on the spindle (non rotating), drive the carriage back and forth with the hand wheel, Advance the cutter with the cross slide. Regards jb ------- Re: Cutting a stepped gear on the lathe Posted by: "Paul Kennedy" clankennedy2004x~xxyahoo.co.uk Date: Sun Aug 10, 2014 3:04 pm ((PDT)) :/ Umm I know aluminum has its uses but a gear? especially a back-gear, I'm not sure but I'm imagining a very short life-cycle on this but then I suppose maybe it's just practice? As for how to cut the teeth I'd imagine some sort of shaper or like you said broach was used for the small pulley where a gear cutter couldn't go all the way due to the larger bull gear. I wouldn't risk dissimilar metals like this on my lathe. I'm thinking the aluminum will wear and create contamination to the rest of your gear train and if a tooth snaps off it could end up stripping teeth of the cast gears. Worst case. Aluminum is soft but .... ------- Re: Cutting a stepped gear on the lathe Posted by: garthnx~xxpbt.co.za garthn444 Date: Mon Aug 11, 2014 1:38 am ((PDT)) Didn't think of cutting the teeth simply using the leadscrew to move the cutter - seems a whole lot simpler than a fly cutter, gear spindle holder, vise etc etc. I have CNC control on lead and cross, will make it a doddle. Any advice on how to shape the cutter? It of course has to match the required profile when viewed end on, but shouldn't dig into the gear? Kind of scrape thin layers away? ------- Re: Cutting a stepped gear on the lathe Posted by: garthnx~xxpbt.co.za garthn444 Date: Mon Aug 11, 2014 1:43 am ((PDT)) The aluminium is very good quality and very hard. This guy says he has had no problems with meshing alu and steel. Cut a lathe change gear: http://users.picknowl.com.au/~gloaming_agnet/cq9325rev7-n1.html ------- Re: Cutting a stepped gear on the lathe Posted by: "Paul Kennedy" clankennedy2004x~xxyahoo.co.uk Date: Mon Aug 11, 2014 4:31 am ((PDT)) Damn You Garth Damn you too hell :D Do you know what you have done ! You've only gone and convinced me this is a viable method to producing gears. I've still got my reservations but now want to give it a go myself. DAMN. Like I don't have enough to do already. :D Ohh god, another item on my project / to do list :( Where will it end. ------- Re: Cutting a stepped gear on the lathe Posted by: "Richard Wilson" richardpwilson61x~xxyahoo.co.uk Date: Mon Aug 11, 2014 4:51 am ((PDT)) It's going to take you a long, long time to cut them like that. Richard ------- Re: Cutting a stepped gear on the lathe Posted by: garthnx~xxpbt.co.za garthn444 Date: Mon Aug 11, 2014 4:54 am ((PDT)) Heh. I know the feeling too well, this is something that has been on my list for months. I am going to try with a tool holder (like a boring bar) mounted at right angles to the bed. Then a cutter bit, flat end when looked at from above, shaped as per the gap between teeth when looked at from the headstock. Clearance ground on the side that faces the bottom of the tooth gap. Hardened and sharpened. The gear will be cut on the side closest to the operator - the height of the cutter is centreline. Hang on, I can just mount the cutter directly in the toolpost, no need for a holder! Then I will experiment with cutting depth per pass. If I can cut .1mm per pass, I need 30 passes. For 21/56 teeth, that is not much fun done by hand, total of 2310 traverses.... With CNC/steppers, it should be great fun and much quicker. This is the reason I need the backgears working, cutting threads by hand is the same issue. I will have to use my my spindle handle and clamp it somehow, shouldn't be hard to figure out a solution. Off to buy some HSS. ------- Re: Cutting a stepped gear on the lathe Posted by: peterroachx~xxbtinternet.com x3cnc Date: Mon Aug 11, 2014 7:34 am ((PDT)) Shaper, Use a slotting head or as suggested a fixed tool on the carriage. My two penny worth, would not use Aluminium, or make the small one steel on a long core/shaft and cast the aluminium blank on to the other end? Other options would be to change the orientation and mill the tooth forms with a small cutter. ------- Re: Cutting a stepped gear on the lathe Posted by: "Kevin" tadpolex~xxbtinternet.com klokenz Date: Mon Aug 11, 2014 2:05 pm ((PDT)) On 10/08/2014, garthnx~xxpbt.co.za [myfordlathes] wrote: > Yes, I thought too about two separate gears, screwed together. I don't > really see why that wouldn't work. I've also been wondering about making > the cutter somehow move in a non-circular motion, can't figure that out. > What do you mean by a shaper? A shaper (or shaping machine) does more or less what "JB" describes in the next post, mounting the cutter in the toolpost and moving it back and forth. Once popular in industry, until vertical milling machines came along. It's the old story, you can do most jobs in the lathe, eventually, but it goes faster on a dedicated machine. All you have to worry about now is how to get the correct profile on the cutter. Or use the rotary cutter and make two wheels. There's no advantage that I can see in having the two gears on one piece of metal. Especially if you already have the cutters. Kevin ------- Re: Cutting a stepped gear on the lathe Posted by: burgoynedanielx~xxyahoo.ca Date: Tue Aug 12, 2014 2:53 am ((PDT)) Change gears used for a leadscrew setup require a fraction of the torque compared to a bull gear. I would not use alu. If you said brass or bronze, okay but still a difficult process. What you are attempting is tricky at best and a recipe for frustration at worst. Don't want to sound pessimistic if you are keen to make things, but this project might not be the easiest for a first time experience in cutting gears. My advice is to source a bull gear, new or old, and then be done with it and then you can enjoy the Myford you have repaired. For shapers, see Atlas or South Bend shaper pages on lathes.co.uk Daniel ------- Re: Cutting a stepped gear on the lathe Posted by: peterroachx~xxbtinternet.com x3cnc Date: Tue Aug 12, 2014 3:20 am ((PDT)) Your aluminum, (aluminum alloy?) may be hard, but probably only half as hard as steel. Two issues: 1. I would suspect the back gears have to deal with higher torque and hence loading than a humble change gear. It will be the shock, dynamic loading that is the issue rather than the running load. 2. The characteristics you are interested in are not hardness but ability to deal with shear stress. Young's, Shear and bulk modulus of Aluminium is only about one third of that of steel! Brass has similar properties to Aluminium from a modulus perspective but the ability to surface work harden. If you have used old pistons then you may well have a good Alloy. Few people damage back gears (?), so if you can control the loading (design rules in your CNC machining strategies) you may reduce the back gear loading and Aluminium Alloy may suffice. Slotting/shaping the gear: Gears should have a rolling contact so IF cut correctly (and some lubrication, etc.) there should be minimum wear. Would suggest a rack form cutter would be the simplest form to cut and would allow a multi-tooth cutter which would small cuts whilst removing material from several teeth gaps. Imagine a flat gauge plate version of Model Engineering Pages: http://homepage.ntlworld.com/peter_harrison/workshop/gearcutting/me thod.htm ------- Re: Cutting a stepped gear on the lathe Posted by: peterroachx~xxbtinternet.com x3cnc Date: Thu Aug 14, 2014 2:15 am ((PDT)) Footnote. I acquired a foundry for a retired colleague, with a better metallurgy knowledge, and have been busy collecting Aluminium scrap. I had identified pistons as a potential source. However he has declined them, as they are high Silicon Aluminium, "hypereutectic." It is a nonferrous, metal-matrix composite with a primary silicon content of at least 11.8 percent. "A HSS cutting tool has little value when machining high-silicon aluminum. It dulls within seconds of contacting the material. And carbide, even coated carbide, reacts as if it had come into contact with a grinding wheel." SO I assume whilst HARD, you have used a material below the hypereutectic point, else please explain what/how you machined the larger gear please. Peter ------- Re: Cutting a stepped gear on the lathe Posted by: "Kevin" tadpolex~xxbtinternet.com klokenz Date: Thu Aug 14, 2014 3:23 pm ((PDT)) > I had identified pistons as a potential source. However he has > declined them, as they are high Silicon Aluminium, Some are, some aren't. Kevin ------- Re: Cutting a stepped gear on the lathe Posted by: "Paul Kennedy" clankennedy2004x~xxyahoo.co.uk Date: Thu Aug 14, 2014 3:02 am ((PDT)) I also would also be interested in how this issue is overcome as obviously a piston has to be bored out for the gudgeon pin and the recesses cut for the Rings. Having never done one myself I simply assumed it was relatively straight forward. I've cut Aircraft Grade aluminum for 747 bulkheads and A380 wing struts and supports and it cuts like butter! Are pistons that different? Maybe the aircraft stuff is softer to allow more flex! ------- Re: Cutting a stepped gear on the lathe Posted by: "Phil" pipx~xxhvtesla.com philiptuck Date: Thu Aug 14, 2014 3:22 am ((PDT)) I was wondering the same, so looking on YouTube I found this: https://www.youtube.com/watch?v=fKdnZbkHwLM The chap is using a front-mounted cut-off tool to machine and enlarge an oil ring groove. Shavings are coming off the same as usual, and it seems to machine without any drama - odd. Regards Phil Tuck www.hvtesla.com ------- Re: Cutting a stepped gear on the lathe Posted by: garthnx~xxpbt.co.za garthn444 Date: Thu Aug 14, 2014 3:45 am ((PDT)) Hi Peter. I used a piston - and also a machined cover that looked high quality. Probably about 50% was from each. So no idea of the real content. It machined fine with a HSS cutter - although it did seem harder than "normal" aluminium, which cuts like butter. This felt a bit more like turning free cutting steel. Regards Garth ------- Re: Cutting a stepped gear on the lathe Posted by: "john baird" alexandra.leavingx~xxyahoo.co.uk Date: Thu Aug 14, 2014 10:57 am ((PDT)) I wonder if pistons made of this material, were used in fail safe applications, like ships' engines, or aero engines, say like the Merlin V12 or (insert your engine type). Doubleboost has a recent video, where he lowers the crown of a motor cycle piston to reduce the compression, (I would have raised the barrel or fitted a shorter con rod) and that seems to machine, without any drama. As an apprentice, we used to machine the skirts off truck pistons, to make ash trays, they were used in all the pubs, (none of those poncy glass ones that break easily). Now you don't see ash trays, even the pubs are disappearing fast. For our overseas readers a "pub" is a public house, where alcohol is served, frequented by men wearing overalls and caps, and playing dominoes, darts and 3 card brag. Regards jb ------- Re: Cutting a stepped gear on the lathe Posted by: garthnx~xxpbt.co.za garthn444 Date: Wed Sep 3, 2014 12:25 pm ((PDT)) Well, it worked - to a degree. But I don't think I will be doing this again, because it took over 100 passes to cut one tooth gap (the cutter was sharp, it was probably not shaped well). I have stepper motors on the lathe - even so, it took almost 10 minutes to cut a single gap. Taking a deeper cut stalled a fairly decent motor. I'm using the gear, its not very quiet and somewhere along the way I messed up the bore a bit (I forced a steel sleeve into it). But hey, I have the backgears working again. And turned a very nice looking test thread under complete CNC control. ------- 3 Jaw chuck broken-what can I do [atlas_craftsman] Posted by: dbq49erx~xxyahoo.com dbq49er Date: Mon Aug 18, 2014 10:04 am ((PDT)) I found a broken tooth on the chuck key gear. The chuck stopped turning and I could not get the part out of the chuck. When I got the chuck apart, I found the tooth embedded in the ring that drives the chuck jaws. The only ID on the chuck was the numbers "6613-1". It is a 6" dia. What are my options? Should I braze or mig weld in a tooth? I could then file or grind in a tooth profile. I do not have a v/h mill so hand work will have to do. Are parts available? Cost to have one make? Find a chuck on ebay? Can any one help? Thanks for any response. ------- Re: 3 Jaw chuck broken-what can I do Posted by: "Charles" xlch58x~xxswbell.net Date: Mon Aug 18, 2014 10:25 am ((PDT)) Weld and file it. I have three milling machines, a shaper and a drawer full of random gear hobs and gear cutters and I would still just weld it and file it to shape. Very low speed gear, perfection not required. Braze should do just as well, but once you braze it, welding is no longer an option. Charles ------- Re: 3 Jaw chuck broken-what can I do Posted by: "Lance Eggleston" gbofx~xxverizon.net crashbone256 Date: Mon Aug 18, 2014 7:45 pm ((PDT)) Another option is 1- flatten the broken surface 2- drill and tap several holes for small steel screws 3- insert screws with Loctite 4- file heads of screws to shape 5- if you want fancy, fill the form with epoxy and shape lance ------- Re: 3 Jaw chuck broken-what can I do Posted by: "Bruce ." freemab222x~xxgmail.com bakmthiscl Date: Mon Aug 18, 2014 8:59 pm ((PDT)) Without examining gear and tooth, I could not advise you with any certainty. However, brazing can be remarkably strong and might be the simplest means of repairing the gear. I'm assuming the gear is steel. Check the fit of tooth to gear. If it's good and can be cleaned free of dirt, grease, and oxidation, then brazing might work well. Support the gear with broken tooth up on, say, a soft firebrick, flux, place tooth on gear, heat with torch as rapidly as possible till the brazing wire melts, and don't use too much wire. For brazing, the whole gear will have to be brought up to brazing temperature. Bruce NJ ------- Re: 3 Jaw chuck broken-what can I do Posted by: wa5cabx~xxcs.com wa5cab Date: Mon Aug 18, 2014 11:14 am ((PDT)) dbq, The model number of the 6" 3-jaw chuck sold by Atlas was 6613. 6613-1 is probably the part number of whatever body piece you found the number on. The part number of the pinion is 6612-53 (6612 5" and 6613 6" use the same pinion). First thing that I would do would be to call Clausing and see whether they still have one in stock. If not, ask them for the drawing. ------- Re: 3 Jaw chuck broken-what can I do Posted by: dbq49erx~xxyahoo.com Date: Tue Aug 19, 2014 11:04 am ((PDT)) Jerry/jtiers:That's what forums like this is all about. Somebody/Many have parts sitting around. Thanks for the name. Some people say that the square drive could be gotten from a 1/4" socket and cut your own gear and weld them together. Another said that make it with the 1/4" square sticking out when you make the gear. Interesting answers from people who have mills, cutters and dividing heads. If only I had such things, let alone the skill. I was so lucky to find the lathe at a price ($200). Having spent 600 additional this occurred. It's like all my other tools, they don't make that part any more. Hell, try to find a good tool any more and the company sells out to anyone and they don't support it. Thanks for responding and are you sure you can't find the pinion -- just kidding. Larry ------- quick change gears [atlas_craftsman] Posted by: tooldocx~xxcheqnet.net davidhallsten Date: Tue Oct 14, 2014 11:47 am ((PDT)) I did a stupid thing this weekend, allowing my power cross feed to try to take out the drill bit that was in the way as i was cross feeding. I heard the "snap snap" and knew i had a problem. I took off the quick change assembly and carefully inspected all the little gears in there and found the one pretty easily, it was the one with two teeth that were not connected to the gear itself. I found a replacement on evil bay and ordered it, however in searching the web, i could not find the other gears that i should probably replace due to excessive wear. My question is, who has them at prices a person can actually afford? I checked sears parts direct and they still have them listed but the prices are more than extreme. I knew they would be but someone is making them for sears. Or could i actually make my own if i knew the specs? That would be fun to try. The ones i would like to replace are:101-546 compound gear, 101-40a, and a pair of 101-48a. Of course i don't need these but it would make me feel like i contributed something to this old lathe if i could get them. Thanks in advance, davidh, the old guy. ------- Re: quick change gears Posted by: wa5cabx~xxcs.com wa5cab Date: Tue Oct 14, 2014 12:37 pm ((PDT)) Call Clausing, 800-323-0972. Ask for old Atlas parts. They aren't cheap, as their prices reflect 21st, not mid-20th, century costs. But they may be cheaper than Sears. As far as making them, you could, although such work is best done on a horizontal mill. But up-front tooling and accessories won't be cheap. An inbetween option is to buy near equivalent gears from Boston and modify them. Two of your part numbers are incomplete. Should be 9-101-40A and 9-101-48A. I think that the third one must be 10-1546. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Re: quick change gears Posted by: "David Hair" thehairsx~xxoptilink.us dhlh1984 Date: Tue Oct 14, 2014 1:28 pm ((PDT)) Evening davidh, Don't you love the trouble you can get into with the crossfeed. I know the feeling when you hear the "snap snap". I'm going the route of making my own gears. I figure buying the involute cutters are a one time thing and I should be able to repair any gear I may need in the future. If you watch you can find the cutters you need used. Having to wait to get my auto feed may make me a little more careful in the future. Wish you well on finding the gears reasonable. Someone else told me about buying replacements from Boston Gear and turning the whole I need and parting them down to size. This looks cheaper than buying new, but I need a gear with a built in key. I would have to cut a keyway in the gear and silver solder in a piece of key. If I'm going to have to go that far I figured I might as well make the whole gear. David Hair ------- Re: quick change gears Posted by: thehairsx~xxoptilink.us dhlh1984 Date: Wed Oct 15, 2014 10:17 am ((PDT)) I forgot about the info needed to cut a gear. Don't just go out and buy the involute gear cutters. Several reasons why. 1. you need to get a good base of knowledge about cutting gears. Get a machinist handbook and read everything about gears. You should be able to find one at your library. Very good reading. 2. If you want to be able to cut any gear from like 6 to 134 or rack you will need 8 different cutters for each DP. 3. If you are like me you will need to make mandrels for the involute gear cutters. All I have at present will use a 1" mandrel. 4 You are going to need some way to index your gear blank and you will also need the handbook to know what size to turn the gear blank to. 5. I am going to use my bench mill to cut my gears. If you are going to use your lathe you are going to need some type of milling adapter. Watch some of the youtubes on making DIY involute gears. David Hair Dalton, GA ------- Re: quick change gears Posted by: "Gregg Eshelman" g_alan_ex~xxYAHOO.COM Date: Wed Oct 15, 2014 11:14 pm ((PDT)) On 10/15/2014 7:21 AM, tooldocx~xxcheqnet.net [atlas_craftsman] wrote: > what is the specs on the teeth ? ie, what cutters are needed ? > and from whom ? You can straight hob involute gears. Cut a multi tooth hob with straight sides on its teeth, same as a 135 tooth to rack gear cutter. Mount the hob to a vertical mill and the gear blank to an indexer at right angles. Align one hob tooth with the centerline of the indexer axis then take a cut. Rotate the gear one tooth and cut again. As the gear is rotated, the upper and lower teeth on the hob create the involute profile. There are videos on youtube showing how this works. This can also be done on a lathe if you make an attachment for indexing the gear. One way to ensure you cut the correct number of teeth is to use any other gear with the same number of teeth as the indexing plate, with something to push into the teeth to hold it. I recently saw exactly that sort of indexer which used die cast Atlas change gears. ------- Re: quick change gears Posted by: wa5cabx~xxcs.com wa5cab Date: Wed Oct 15, 2014 11:53 pm ((PDT)) The horizontal indexer sold by Atlas for their horizontal mill uses 6" change gears for indexing. I think that of the three commonly available machine tools for hobbyists, the horizontal mill is the best choice for making straight tooth spur gears. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Re: quick change gears Posted by: tooldocx~xxcheqnet.net davidhallsten Date: Thu Oct 16, 2014 8:17 am ((PDT)) i think i can cut the gears if i knew the cutter / profile / form, or tooth form. the machinery and set up stuff is here along with the time. mill, rotary table with index, i suppose i could try to cut my own cutter based on the existing good gears, but i think that would be above my pay grade. now if they were herringbone gears, i probably would concede to purchasing them. :) back to the orig. question. . . help ? -------- Re: quick change gears Posted by: "David Hair" thehairsx~xxoptilink.us dhlh1984 Date: Thu Oct 16, 2014 4:12 pm ((PDT)) If you are planning on grinding a single point tool you can use another gear with near the same number of teeth that will mesh with the bad gear as a pattern for grinding. The left gears in my 12x36 lathe QCGB seem to all be 16 DP so any change gear with near the same number of teeth should work. The gears on the right side are 20DP so you would need to use a gear on that side of the QCGB with a close number of teeth to make your single point tool. I went the route of buying a gear tooth gauge set. I bought a Fowler set #52-470-140 that was made in Japan. Boston Gear also makes a very good USA made gauge set. I then bought the involute gear cutters I needed for the correct number of teeth per gear. Go to this link in the home machinist forum and check the conversation on cutting involute gears. http://www.chaski.org/homemachinist/viewtopic.php?f=4&t=88834 Also check out " DIY involute gear cutting " in Youtube. You will find several videos on the subject using both mills and lathes. They say a picture is worth a thousand words so a video must be worth volumes. This site has all kinds of information on gears. http://www.gizmology.net/gears.htm David Hair Dalton, GA ------- [atlas618lathe] Does any one knows what is the pitch for the gears on the 618? Posted by: migueldeservantesysaavedrax~xxyahoo.com Date: Thu Feb 12, 2015 5:34 pm ((PST)) Someone made a comment that if one have a dividing table or indexer it was possible to make the gears for this lathe, so does anyone know off the top of their head what the pitch is! I have been looking for a long time for the gear making dies that are sold on Ebay and was wondering, and since I'm one of the one's that is interested in making a "Quickomatic quick gear change for this lathe, I was hoping to know if someone has that information. ------- Re: Does any one knows what is the pitch for the gears on the 618? Posted by: n1ltvx~xxyahoo.com n1ltv Date: Thu Feb 12, 2015 6:26 pm ((PST)) Mark, The pitch for the 618 lathe gears is 24, with 14.5 degree pressure angle. Hank ------- [How to repair a gear's missing tooth.] Re: 21/56T back gear cluster [myfordlathes] Posted by: "Richard Wilson" richardpwilson61x~xxyahoo.co.uk Date: Tue Jun 9, 2015 2:24 am ((PDT)) For the one with only one tooth missing, can I suggest this trick, which I have used successfully on 16DP changewheels with the odd tooth missing. Unfortunately, it has to start with the removal of the gear from the lathe. Hold in the vice, and file down any remaining stub of the broken tooth, then cut a slot, the thickness of a tooth, about 3/8" deep at the position of the missing tooth. Slot can be milled in, if you've got the equipment, though I used a hacksaw with 2 blades in it followed by a warding file to do mine. Cut a small piece of sheet steel of the same thickness as a tooth and locset it into the slot (which should be a good fit to start with). Then when that's gone off, file the steel to match the width and height of the adjacent teeth, finish by profiling the new tooth, again with the warding file, to match the existing ones. Super precision isn't needed, do it 'by eye' then check if the meshing gear rolls nicely past the new one. I can do one of these repairs in not much longer than it's taken me to write this, and I haven't had one fail yet. ------- [Thread is actually about gear sources for Myfords, and others.] Just to introduce myself. [myfordlathes] Posted by: bick1x~xxverizon.net bick1027 Date: Mon Oct 5, 2015 3:27 pm ((PDT)) Hi all, A new member here so thought I'd say "Hello". I'm Bob from Delaware in the U.S., I'm an oldster of 81 years and have a Myford Super 7 with imperial gearbox which I bought new in the early '80's. I'm a hobby machinist (?), self taught from books (L. Sparey's "The Amateurs Lathe convinced me I wanted a Myford), other machinists and now the internet. I'm slowly learning to navigate this group so if I make some errors please forgive! I arrived here after 'googling' "Metric threads on a Myford lathe". I found a file in the Files section which gives some information but I'd like to know where I can obtain the proper 33, 34, 35 tooth gears to enable me to cut metric threads (years ago I looked into buying the Myford metric set but it was cheaper to buy a Chinese lathe just to cut metric threads). Anyway, thanks for reading and I hope to be able to contribute. Bob ------- Re: Just to introduce myself. Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7 Date: Mon Oct 5, 2015 3:50 pm ((PDT)) Welcome to the group! I’ve gotten my special gears from several sources. The eBay seller “myford-stuff” often has gears. He currently lists a 35T at http://www.ebay.co.uk/itm/Original-Nottingham-Myford-ML7-ML10-Su per-7-Lathe-Teeth-Tooth-Change-Gear-Gears-/181161546675 I have gotten some gears from Lathe Spares http://www.lathespares.co.uk Home and Workshop Machinery http://www.homeandworkshop.co.uk/ are easy to deal with and often have them. There is always RDG who bought Myford http://www.myford.co.uk They currently have several gears including the 33T, 34T and 35T. ------- Re: Just to introduce myself. Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Mon Oct 5, 2015 3:58 pm ((PDT)) Hi Bob, Welcome to the group. You can get the gears you want from RDG Tools in the UK rdgtools.co.uk at 10 UK pounds each. Regards, Alan ------- Re: Just to introduce myself. Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7 Date: Tue Oct 6, 2015 9:53 am ((PDT)) I am in Canada and I believe that you are in the US so ordering stuff from the UK is different from a UK based purchaser. The good news is that UK prices are usually quoted including VAT so a foreign purchaser will save 20% on the quoted price since the Value Added Tax does not apply. I have placed several orders with RDG with varying degrees of satisfaction. Note that they started life selling poorly manufactured copies of genuine Myford accessories. In my experience RDG sometimes ships poorly packaged cr*p without proper customs documentation. This leads to damaged goods, additional costs to the receiver and it not being worth it to ship the item back at your expense. ------- Re: Just to introduce myself. Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Tue Oct 6, 2015 10:17 am ((PDT)) You are right, Ken. RDG has an indifferent reputation for both quality and service. I mentioned them only because they have the gears that Bob needed. The only alternative I could find from a quick trawl of the web was people selling odd individual gears second hand. Certainly I would not steer anyone in the direction of RDG if they can find what they want elsewhere. Regards, Alan ------- Re: Just to introduce myself. Posted by: "Peter Moore" zzpeter3x~xxyahoo.co.uk zzpeter3 Date: Tue Oct 6, 2015 10:35 am ((PDT)) Try Bede tools; they sell second hand parts, are very helpful, and Barry will send parts all over the world. Bede Tools and Machinery New and Used Quality Tooling and Light Machinery Bought and Sold, Supplying the Model Engineer and Light Engineering Industy. View on www.bedetools.com Hope this helps Peter ------- Internal Gear [sherline] Posted by: jlkiefferx~xxcharter.net n2562001 Date: Mon Nov 9, 2015 9:40 am ((PST)) Now that disputes have settled down again, Why not stir the pot a little as they say. A while back, someone requested information on cutting internal teeth in a gear that was 3/8"- 1/2" in diameter. At the time, I was very busy and did not have the information needed to support my disputed personal suggestion. I now do, but have not reread the posts and will go from memory. Thread consensus was that internal gear teeth are manufactured by broaching. In general this is correct. In addition as I recall, the again consensus was that the OP purchase or make a broach to cut these internal teeth. If I had personally been requesting the information, this suggestion would not have been useful. First, I do not think those suggesting this realized how small a 3/8"-1/2" hole really is in relation to cutting teeth. Nor that tooth size will depend on what is practical for the smallest internal pinion that in this case will likely be under .125" in diameter. One quickly finds that broaches in the sizes required (150-200 DP) are of course not available unless by very very expensive special order. And then only Maybe. Nor did anyone suggest a practical home shop method of making a broach. Especially how to accurately grind various teeth profiles that are only .010"- .012" in height. My personal suggested option was to place the gear blank at a 30 degree angle and pass a standard gear cutter through the ring per photos under my name. The suggested readily available cutter was a .14 module cycloidal cutter by PP Thornton (compatible to approx. 180 DP). Comments as I recall ranged from, It's not supposed to be done that way, They don`t make cutters for that, You can`t do it that way etc etc. To understand my suggestions you would need to understand my personality. It is such, that if a common procedure will not resolve a problem, I could really care less how its ever been done or who has done what. At this point I am looking for a practical solution that is mechanically sound and can be performed in a timely fashion. Again regardless of who or how it has ever been done. If the solution can be demonstrated as sound and may be of interest, it is included in public demonstrations as in this case. While I knew that the suggestion produced sound results from cutting both larger and smaller internal teeth, I had not cut teeth under the exact recommended scenario until now. In a recent public demo, I decided to check results from the exact recommendation. The hole was mid range at .430" with 82 teeth in the outer ring. Not all teeth were cut in the outer ring due to demo time, but enough to check results. The pinion is about .110" diameter with 20 teeth. Again the cutter was a .14 module cutter designed for 20 teeth to rack. Photo`s of the result can be seen under my name in the photo section. All teeth are fully formed despite my poor photography. Flow of power is very smooth with absolutely no detectable backlash at full depth. An added advantage is that The tooth angle increases tooth length increasing strength. Since these examples are very small, I will put them in my travel kit for anyone to inspect and play with at the many shows I attend. Jerry Kieffer ------- Re: Internal Gear Posted by: "Douglas Vogt" dbvogtx~xxyahoo.com dbvogt Date: Mon Nov 9, 2015 10:13 am ((PST)) Nice photos, certainly not "poor." For interested clockmakers, Bill Smith's manual on a "How to Make a Strutt Epicyclic Train Clock" shows how he made the ring gear by passing a .8M cutter through it. There were some comments several years ago about the shape of internal teeth cut with a Thornton cutter and the related problems but apparently no one informed the clock that it wouldn't work. ------- Re: Internal Gear Posted by: "Gerald Feldman" gfeldman2904x~xxpacbell.net rsojerry Date: Mon Nov 9, 2015 10:48 am ((PST)) Doug, Those individuals are called naysayers, and they are all too common. I cannot count the number of times I’ve been told, “But, that won’t work.”, only to find that whatever was done worked just fine. Those individuals do serve a valuable purpose though, and that is to make us to test hypotheses, and thereby advance science. Jerry F. ------- Re: Internal Gear Posted by: "procter" procterx~xxihug.co.nz kwstse Date: Mon Nov 9, 2015 10:25 am ((PST)) It's a matter of load applied to the gears. Clock loads are relatively light and/or low speed. My efforts with internally toothed gears has been for model railway locomotives where the motor shaft speed being reduced is 0-10,000 rpm. Mechanical load is relatively high, several kilograms of rolling stock being towed behind the locomotive. I don't want to have to remake the gear every week or every year. Consequently, I can't claim any success to date. Faulhaber of Switzerland makes beautiful little gearboxes . Greg.P. Hukerenui, New Zealand ------- Re: Internal Gear Posted by: jlkiefferx~xxcharter.net n2562001 Date: Mon Nov 9, 2015 1:12 pm ((PST)) Greg. As mentioned, I have used various tooth profiles including involute without issue. As long as the teeth are fully formed and fill the tooth space`s without excessive backlash at full depth, other issues should be explored. These will include alloys, alloy selection, hardening and tempering. Unfortunately, the average home shop machinist will typically have problems finding and utilizing special alloys used in critical areas of manufacture. The very precise and expensive hardening and tempering equipment are also not typically found in a home shop setting. However unorthodox creativity can many times overcome issues. Jerry Kieffer ------- Re: Internal Gear Posted by: jlkiefferx~xxcharter.net n2562001 Date: Mon Nov 9, 2015 12:50 pm ((PST)) Someone has pointed out a discrepancy in the photo of the pinion mentioned. After measurement, it actually has 33 teeth and is .175" in diameter. It seems like what I recall and actually did were two different things. It should also be noted, that I have used various tooth profile cutters including involute with the same result. The only reason PP Thornton was suggested in the case was because the small diameter of the cutter would pass though the OD. The reason that this works as well as it does, is because of the small tooth required in internal gears based on the smallest pinion. Because of the very small teeth profile, what the cutter sees is virtually a flat surface similar to a rack. Reduced tooth size from the ark is so minuscule it has virtually no effect on anything under normal applications. While it works superbly for one off home shop applications where gear width limitations are within requirements, it is not a good fit for production since broaching machines are more versatile. Jerry Kieffer ------- Re: Atlas H36 change gears question [atlas_craftsman] Posted by: "Gregg Eshelman" g_alan_ex~xxYAHOO.COM g_alan_e Date: Fri Jan 15, 2016 9:07 pm ((PST)) On 1/15/2016 2:20 PM, fuddie_duddiex~xxyahoo.com [atlas_craftsman] wrote: > I just got an Atlas H36 lathe without the change gears. I do have the > lead screw. Once I got it home, it occurred to me that the seller was > probably trying to partially part out the lathe. I did manage to get the > lead screw off him, but he was going to have to look for the change > gears as they were misplaced. > My question is, can I just get a set of Atlas change gears off ebay, are > they all the same across all Atlas lathes? Does anybody know? If all else fails, some people have successfully 3D printed change gears for Atlas lathes using Nylon. The files are on Thingiverse. NOTE TO FILE: This message is just one out of many in this discussion, with members detailing which gears fit what other Atlas lathes. ------- ------------------------------------------------------------------ This is just one of some 80 files about machining and metalworking and useful workshop subjects that can be read at: http://www.janellestudio.com/metal/index.html ------------------------------------------------------------------