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 more than 70 additional files on my home page Machining and Metalworking at Home http://www.janellestudio.com/metal/ 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 - 2010 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 Koøenský 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 ------- 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. -------