This file includes turning tips for brass on a metal lathe, as well as some milling machine tips. While brass is fairly easy to turn, there are some differences compared to any prior experience with steel or aluminium. 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 - 2008 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. ========================================================================== Date: Wed, 07 Mar 2001 12:02:39 -0000 From: brewerpaulx~xxaol.com Subject: Brass turning questions Hi-- couple of newbie questions here. Been using my 6" for wood turning ( pens) but now I need to use it for some brass turning. 1) What type (material) tools should I use? 2) How fast approx. should the lathe be turning? 3) Been told I need cutting oil, especially for cutting off-- what exactly is cutting oil? Can I use the same stuff I use to lube the lathe? Thanks. ------- Date: Wed, 07 Mar 2001 07:01:17 -0600 From: "Skip Evans" Subject: Re: Brass turning questions 1. High speed Steel will work. I buy carbide tooling from Enco. It is very affordable, especially when on sale. 2.Contact clausing for an owner's manual. It will answer speed questions and most other operational questions you will have later. It is well worth the $25.00. 3. I use lubrication only when threading. Brass and aluminum turn beautifully with correct speeds. After turning steel I usually apply a little emory cloth to shine things up. ------- Date: Wed, 07 Mar 2001 11:09:15 -0500 From: David Beierl Subject: Re: Brass turning questions At 08:01 AM 3/7/2001, Skip Evans wrote: >3. I use lubrication only when threading. Brass and aluminum turn >beautifully with correct speeds. After turning steel I usually apply a >little emory cloth to shine things up. Also, there are many different types of brass -- if you're buying new you're probably getting "free machining" Alloy 360 (60 Cu, 36 Zn, 3 Pb) which turns like butter. From scrap it could be almost anything., including various bronzes. Some are soft and tend to tear, especially if the tool isn't very sharp. Others are very hard. The free-machining stuff is a bright clear golden yellow -- other colors will certainly have different characteristics. I'm working with some 2 1/4" bar now that I happen to know is Aluminum Bronze because it has a typed label stuck to the end of the bar -- turns OK but it's a completely different animal, and it rings like a bell. It's fairly pale with a faint hint of red. And I've got a bar of some other stuff that's much deeper reddish yellow than the 360 -- it's soft and stringy and tears -- no fun to turn. It isn't strictly the copper content -- the Aluminum bronze is 90% copper and it's quite hard. On the tooling, Sherline website has useful instructions on tool grinding. Tools for brass are generally like tools for steel except that they meet the work at a right angle instead of jutting up into it. Likewise if you're drilling brass, carefully stoning the cutting edge to give a zero or slight negative rake (i.e. the edge actually leans slightly away from the cut) may be useful, as well as using a drill with a shallow point and not much end clearance angle. Pilot drilling is important. A home-made spade drill can work extremely well and doesn't tend to bind in the hole. Clear your chips often. David Beierl ------- Date: Wed, 7 Mar 2001 22:07:01 -0600 From: "J Tiers" Subject: Re: Brass turning questions Last poster wrote: >>3. I use lubrication only when threading. Brass and aluminum turn >>beautifully with correct speeds. Certainly true of much brass, I never even had trouble with it on the AA lathe. (Disagree about most aluminum, but never mind). In fact, I think the AA was designed to turn brass, not steel! Brass naturally works well on my bigger machine, also. Generally any "brass-colored" brass will be easy to turn, it seems. Brass does have a tendency to pull the cutter in, hence the lack of rake on brass tools. If you have cross-slide backlash you may with some brasses have a surprise as to your cut depth. A negative rake, or running slightly below center will alleviate this, I have found. I would not bother with carbide, HSS works better and can be made sharper for brass. Jerry ------- Date: Sun, 11 Mar 2001 23:53:31 -0600 From: Jon Elson Subject: Re: Working brass tubing-help please! brewerpaulx~xxaol.com wrote: > Hi-- just ordered some .75 OD, .12 wall brass tubing to make some > fittings for wooden Irish whistles (rings, and ferrules for the > mouthpiece. I need to bore the ID out a bit, turn the OD down a bit > and contour the rings decoratively, and finally cut off the parts. > My question is, how long a piece of this tubing I reasonable chuck in > my 6" ( 3 jaw) with the tail end unsupported? Also, how much stock do > I need to put into the chuck. I figure I need about 2" for the parts > I plan to make including 1/16 waste on each cutoff,plus about 1" > wasted in the chuck-- sound do-able? There may be some tricks to reduce waste. One way, of course, is the expanding mandrel. Cut the tubing to just over the length of the actual part. Chuck very lightly in the 3-jaw, and bore the ID to desired size. Take a piece of aluminum bar and turn down the OD to just a hair (.001" or so) under the ID size. Drill a hole in it, tap it for a 10-32 thread or thereabouts, slot it 2 ways with a hacksaw or other available tool. Finally, countersink the hole to match a flat-head screw that matches the thred. Now, when you drive the screw in, it will spread the 4 'fingers' left when you slotted the turned-down end of the bar. With the tube over this mandrel, you can turn the OD, and also face both ends. When I make these, I usually turn a narrow taper in the mandrel, and make a custom screw with a matching taper that runs the length of the fingers. But, that might be taxing the skills you have at this point. > Oh yeah- the rings will be rounded in contour, so I need to cut > from right to left and left to right. Rather than changing from RH > to LH cutting tools, can I simply use a symmetrical tool such as a > threading tool for this soft metal. If you can't guess, I'm a total > newbie..... Any and all help appreciated Yes, you should be able to. The one problem is that in most turning on light lathes, you can't have too wide a face on the cutter contacting the work at one time. The wide chip produces a lot of chatter, and rough surface finish. Jon ------- Date: Mon, 12 Mar 2001 15:11:09 -0000 From: "Jim Lewis" Subject: How to drill brass OK, guys, what's the trick for drilling brass? I need a 1/2" hole thru 2" of brass and I tried every way I can think of. It binds no matter what, creating a nightmare of a job. Jim ------- Date: Mon, 12 Mar 2001 10:51:46 -0500 From: "Rich D." Subject: Re: How to drill brass Jim: Use a cutting oil. The brass is rubbing off on the drill lands and binding. Also, grind the cutting edges to zero rake. Just rub the leading edges on an oil stone (drill axis parallel to stone surface) to flatten the edge a little. This will prevent grabbing when the drill breaks thru. Be sure the drill is sharp, especially at the outer corners. Rich D. ------- Date: Mon, 12 Mar 2001 22:31:05 From: batwingsx~xxi-plus.net Subject: Re: How to drill brass At 03:11 PM 3/12/01 -0000, you wrote: >OK, guys, what's the trick for drilling brass? Negative rake. Stone the edge of the drill very lightly blunt. You would also be advised to have a good bit of spindle power for this size bit. You might do better drilling pilot hole first, but this does increase tendancy to bind unless rake is exactly right. Regards, Hoyt ------- Date: Mon, 12 Mar 2001 17:23:48 +0000 From: Tony Jeffree Subject: Re: Drilling Brass At 10:50 12/03/2001 -0500, you wrote: >Jim, grind a negative rake on your drill bit. Joe Harmon Zero rake is just fine. However, why not drill it undersize & use a boring bar to finish it? Regards, Tony ------- Date: Mon, 12 Mar 2001 09:46:30 -0800 From: "Nicholas Carter and Felice Luftschein" Subject: Re: Drilling Brass I would centerdrill, then use a 1/4" bit w/neg-zero rake to drill the hole, followed by 3/8" then 1/2" The negative rake means that you need more power and force to drill with. I have a complete set of drill bits that are all flatted on the lips to zero rake, makes it easy to do brass projects. Just retire dull bits from your regular collection to brass duty and hone the edge flat. You will go absolutely insane trying to drill holes in brass with regular bits. ------- Date: Mon, 12 Mar 2001 19:03:06 -0000 From: n2562001x~xxyahoo.com Subject: Re: How to drill brass Jim, I have drilled 1/2" and larger holes in brass much deeper than 2" with absolutely no problem with standard drill bits. In fact I have even drilled oil-lite with out a problem. I suspect the problem is with the qaulity of your drill bit. I solved almost 100 percent of my drilling problems when I switched to high end US made drills. Of course you need to drill at the proper speed with proper feed rate. Jerry Kieffer ------- Date: Mon, 12 Mar 2001 22:53:37 -0000 From: lasernerdx~xxhotmail.com Subject: Re: How to drill brass I find that drilling brass is pretty easy if you take a sharpening stone, and LIGHTLY dull the drill bit - no need to regrind. If they are sharp, they'll grab real good (had a chunk of brass in a beautiful new Bison chuck on a Harrison M250. Ran a sharp ~7/8" drill through it. Drill grabbed, chuck was still spinning - brass was not, and then the drill came out of the tailstock. Scary stuff). It's also a good idea to LIGHTLY dull your drills if you drill a lot of aluminum - most notably on the drill press. If you dull the drill it won't be as likely to grab and remove your thumb. Of course, you'll need to resharpen the drill, or use a sharp one for steel. Regards, Robin ------- Date: Mon, 12 Mar 2001 15:55:26 -0800 From: "Nicholas Carter and Felice Luftschein" Subject: Re: Re: How to drill brass I don't know about dulling drills for Al, but I do find that if you don't use lube often the drill will load up and seize in the hole from chip welding and packing - I prefer a sharp drill myself. The brass drills actually are sharp, but 90 deg. corner sharp. You are right, when one says "regrind" for brass, usually a hone across the face will work fine. ------- Date: Sat, 9 Feb 2002 10:27:48 -0800 From: "Brad Butler" Subject: Re: Re: Hand Graving Brass Get in touch with Home Shop Machinist Magazine as they were the ones that ran the article on building the T-Rest. And yes it is very necessary when using gravers on your Sherline. It is a fairly easy part to build, mine only took me about 1 day. If you can't find the magazine let me know and I will photocopy the article and send it to you if you want. Brad Butler ------- Date: Sat, 9 Feb 2002 11:52:51 EST From: WRSmith2x~xxaol.com Subject: Re: Re: Hand Graving Brass <> Hi Terry: Your friend is quite right about the wood rest not being strong enough for metal turning with a hand held graver. I am the one who designed and built the first T-rest which Sherline now offers. It greatly expands the usefulness of the lathe. For brass and other soft metals, be sure to use a beveled graver to avoid grabbing. If you wish to investigate the matter further, in my workshop I have produced a 2-hour video, Graver Making & Hand Turning for Clockmakers & Modelmakers. This will teach you things you would not live long enough to learn by yourself. For information about it, check my Web site http://horology.magnet.fsu.edu/wrsmith.htm Good luck with your hand turning efforts. TTYL W. R. (Bill) Smith, BSME, FBHI, FNAWCC, CMC, CMW, CMEW. 8049 Camberley Drive Powell, TN 37849-4218 Phone: 865-947-9671 http://horology.magnet.fsu.edu/wrsmith.htm Awarded: Metal Working Craftsman of the Year 2000 by the Joe Martin Foundation for Exceptional Craftsmanship. ------- Date: Tue, 09 Apr 2002 21:38:04 -0000 From: "frtcarsareit" Subject: Turning the finial top for a signal I am in the process of turning an HO scale finial top to a railroad signal. The top will be shaped like a Hershey's Kiss in brass. The finial height is only about 1/8th of an inch. I intend to leave a .073 shaft that I can thread using a 1-72 die. The finial will then thread onto the top of the signal mast. How can I turn the curvey shape? I was considering buying the hand-held turning tools from Micro-Mark, but these seem dangerous to use on brass. The Sherline handbook suggests having a custom cutter made, but I think that would be too expensive. I am concerned that using a small jeweler's file could become a projectile. Any ideas or suggestions where I can get a custom cutter ground, or other ideas for cutting the tops? A brand new member! Mark Vaughan ------- Date: Tue, 09 Apr 2002 15:06:37 -0700 From: Alan Marconett KM6VV Subject: Re: Turning the finial top for a signal Hi Mark: It's OK to use a file on the lathe, just use a handle, and don't stand directly in back of it! Use light strokes, and get the "feel" of the file on the work. Keep your fingers AND the FILE away from the chuck! Alan KM6VV ------- Date: Tue, 9 Apr 2002 21:28:38 -0400 From: "Carol & Jerry Jankura" Subject: RE: Turning the finial top for a signal Hi, Mark: Welcome to the group. You might want to search back several messages for a few from Daniel Munoz. He shows how he ground a standard tool bit with a dremel tool to make finials for curtain rods for a doll house. The technique for your RR parts would be exactly the same. His work is really nice, and HSS tool bits aren't very expensive. Jerry -------- Date: Tue, 9 Apr 2002 21:42:23 -0400 From: "David Simmons" Subject: Re: Turning the finial top for a signal Welcome Mark: If you have a bench grinder handy you can grind the tool yourself. Keep a cup of water near by to cool the HSS blank and your finger tips. I can't count how many times I have smoked my fingers:) Look at the standard Sherline tools for some ideas on how to shape the tool, and take your time. People keep telling me how hard it is grind your own tools, but it really is simple once you learn. Later, Dave S. ------- Date: Wed, 10 Apr 2002 02:16:32 -0000 From: "les_grenz" Subject: Re: Turning the finial top for a signal Hi Mark: Here is where hand gravers shine! I would suggest looking up W.R. Smiths web site. You should be able find a link to it on the Sherline website. He has an downloadable article on making and using hand gravers. They work great for decorative turning such as your finials. Regards, Les http://www.lesgrenz.homestead.com/Leshomepage.html ------- Date: Wed, 10 Apr 2002 00:00:30 -0400 From: "Daniel Munoz" Subject: RE: Turning the finial top for a signal Hi Mark, You will find some examples about grinding bits here on my site: http://www.nutsnbits.com/pole_curtains.htm Jerry nice comments about my work said that it could be similar to what you want to do (I myself have no idea what a finial top looks like ;) !) The shaped brass parts on the page are 1/4" diameter. For cutting a 1/8 diameter part and avoid deflexion, my recent experiences show me that you should start from a larger bar, maybe 3/16" or better 1/4". That way there will be much more metal that support the base of the part until it is finally cut to size. See also the page where I describe the gun's ammo http://www.nutsnbits.com/tank_guns.htm , the smallest is about 1/8" diameter and I did finish the nose with a file. I use a lot the files. The muzzle brakes where shaped like that, starting from a rough cone. The really danger in using a file is to hit by mistake the chuck. That is **REALLY** dangerous !!! You could break your fingers or worse ! Try to handle the file as far as possible from the chuck, and you should be safe enough. Or better, grip your metal bar on a collet, that way you will be able to file very close without much danger. Also, avoid to have yours hands stuck under the rotating piece. I did that once, and that hurt !! Fortunately, there's no need to rotate at high speed while using a file, so the motor will hopefully stop before serious damage occurs. If you file on the back side of the part, the file behind the piece, then the tendency will be to push up your hands and the file instead of pulling them down. It will be much safer. I also had good results with fine bands of hard aluminium oxide sand paper. it eat metal quickly, and it is much less dangerous than a file. But also less precise, of course. Hope that could help you. Show us your results :-) Daniel ------- Date: Wed, 10 Apr 2002 08:12:52 -0400 From: "Bill Rutiser" Subject: RE: Turning the finial top for a signal When filing in a lathe, think carefully about where the file will go if it snags on something. In particular, do not hold a file so that the tang is in your palm or against the heel of your hand. A snag here would lead to a very ugly injury. I usually hold the handle end from the side with my left hand, and the other end with my right hand. My arms and elbows are over the bed and tailstock. I try to keep my face out of the likely "plane of flying pieces". Bill Rutiser Gaithersburg, MD, US ------- Date: Wed, 10 Apr 2002 10:08:33 -0500 From: Ron Roske Subject: Re: Turning the finial top for a signal Have been following this thread with interest as I am interested in turning small items from time to time. The subject of using small tools around spinning chunks of metal has always bothered me. One thing that I haven't tried is to use the steady rest to keep the area that one is working on away from the chuck. Is there any reason that this wouldn't work? Another thing that I've given some consideration to is rigging up some type of shield that could be lowered between the right face of the jaws and the area that I'm working on. Does anyone know if that technique has been tried with any success? RonR ------- Date: Wed, 10 Apr 2002 12:01:37 -0400 From: "Daniel Munoz" Subject: RE: Turning the finial top for a signal >One thing that I haven't tried is to use the steady rest to keep the >area that one is working on away from the chuck. >Is there any reason that this wouldn't work? Ron: My opinion I that could work in some cases, but not for very small items. The problem is that when you turn a small item, you need to be close to the chuck because the item is so small. If it is both small *and* away from the chuck, there's chance that the metal will bend. And supporting it with a live center is not always possible, especially in forming thinks with a round top with a file. >Another thing that I've given some consideration to is rigging up some >type of shield that could be lowered between the right face of the jaws >and the area that I'm working on. >Does anyone know if that technique has been tried with any success? I was considering to make a shield with a Plexiglas plate, thin enough to keep the space needed between the piece and the chuck as small as possible. It would also be convenient for normal lathe operation, because when you turn at high speed a small item very close to the chuck, surely turning the wheel of the wrong direction will be a disaster. I was afraid about that even more than using files, because I keep the speed slow with a file, but while lathe cutting very small items you need to go at high speed, especially using carbide bits. Daniel ------- Date: Wed, 10 Apr 2002 13:00:36 EDT From: wanlikerx~xxaol.com Subject: File in a lathe >How can I turn the curvey shape? Try to find a file with a curved surface, half round or a chain saw file, properly applied with a gentle touch and you can make the shape of your choice. A flat file will be hard to control without getting ridges and gouges on it. You can finish the contour with sandpaper. bill ------- Date: Wed, 10 Apr 2002 21:43:22 -0700 From: "Marcus & Eva" Subject: Re: Turning the finial top for a signal Hi Ron: Both of the solutions you describe will work very well, and are not difficult to implement. The most common way, however, is to use collets rather than 3 jaw chucks for freehand turning, and by implication for filing as well. Another good solution that was alluded to earlier in this thread, was to use big enough diameter bar stock that you can stick it out far enough from the chuck to minimize the risk. My personal favorite is to make a form tool, so I can get my desired shape repeatably under mechanical control. I am well set up to do this; probably the biggest contributor for this type of task is the use of a dental turbine to quickly shape my form- cutters under good control. Others will have other solutions; for example I know that Bill Smith (the clockmaker) is so good with gravers that he'll have his shape cut before I've ground my formtool, but I'll bet I can make 20 of them quicker than he can once I'm set up. So... different strokes for different folks. Your solutions are good ones. Cheers Marcus ------- Date: Thu, 11 Apr 2002 20:29:38 -0400 From: ron ginger Subject: Re:Turning the finial top for a signal I assume you are going to do more than one of these parts. Most model RR's Ive seen have dozens of signals. This rules out any of the hand methods because you will have great trouble getting them to all look alike, and it will take a long time to make each one. A form tool, ground to the shape of the part is the obvious answer, and someone has already posted a link and some great photos of several such form tools. My suggestion is slightly different- instead of grinding the form tool from a 1/4" sq blank I made up a tool holder like the standard carbide insert holders. I make the form tools form thin metal- about 1/16" has worked well. Get the hardening tools steel in the flat ground stock form. If the form tool will have round sections make them by drilling a hole of the proper size in the blank, then cut off one half of the blank to leave the cutting edge. This works just like a form tool, but is easier to file/grind to shape because its only 1/16" thick, and one strip of the ground flat stock a foot or so long will make many dozen form cutters. After its filed to shape it takes just a second to heat it red and dump it in water/oil as appropriate to the stock you used. I dont bother to temper them, full hard is fine since they are well supported by the holder. ron ginger ------- Date: Tue, 19 Nov 2002 17:10:53 -0000 From: "bursulescu" Subject: lathe tools [taigtools] Hi gang: New guy to your group. I've had my Taig lathe for one year now. I love it! Just one question though. I'm turning mostly brass (1" rod) and I've worn out my round nose tool. It's beyond repair as far as grinding goes. I checked around and the only replacement tool I could find was Lee Valley. They sell these in sets of six which I don't need. (I already have the full set). I found a web site that sells carbide inserts for the Taig (Plastools.com out of Bellingham, Washington). He assured me these would be perfect for brass. I can't seem to get a good finish with these. Lots of tool chatter and it looks like I'm cutting threads on the brass. I've tried different speeds, feed, etc. with no luck. The old, dull HSS still cuts better than the new carbide. Am I doing something wrong or am I out $105 because they're not meant for brass? Help! P.S. I live in Canada so obtaining separate tools from Taig is somewhat of a hassle. ------- Date: Tue, 19 Nov 2002 10:48:59 -0800 From: "Nicholas Carter and Felice Luftschein" Subject: Re: lathe tools I can always send out a single lathe tool no problem in an envelope. What I think you ought to do is invest in a bench grinder and learn how to sharpen tools. Brass wants zero rake, a flat top to the tool, so it won't dig in. Did you shim the plastools tool so the tip is on center? Is it too high? You also should run pretty fast. See our web pages http://www.cartertools.com/nfhome.html ------- Date: Tue, 19 Nov 2002 14:02:23 -0500 From: Daniel Munoz Subject: Re: lathe tools >site that sells carbide inserts for the Taig (Plastools.com out of >Bellingham, Washington). He assured me these would be perfect for >brass. I can't seem to get a good finish with these. Lots of tool I have very good results with carbide brazed bits on a Sherline, but Taig is equivalent in size and power I believe. I never used carbide **inserts**, but I know the trick with carbide is to run at high speed, and don't be afraid to cut using (relative) large feed. I have a very good finish with my carbide brazed bits, using them on steel, aluminium, brass, and even acrylic rods. On brass it's near mirror finish. BTW, as you live in Canada try KBC Tools www.kbctools.com and ask for their huge catalog, it's free. You'll find there various carbide inserts, maybe yours are not so good after all. Also, maybe give a try to carbide brazed bits. For me, their ref. 1-425A-104 and 1-425B-104 (AL and AR turning and facing to square) cover almost all my needs, even if I couldn't resist to buy one of each type at 3 $ a piece. And using brass only it will never wear. I abuse mine since a year and it still cuts just like the first day :-) In fact, I only go back to HSS when I need some specific grinded shape. Cheers ------- Date: Tue, 19 Nov 2002 19:53:00 +0000 From: Tony Jeffree Subject: Re: lathe tools At 17:10 19/11/2002 +0000, you wrote: >I'm turning mostly brass (1" rod) and I've worn out my round nose tool. >It's beyond repair as far as grinding goes. No HSS tool is beyond repair as far as grinding goes until you've ground it so much that there is no shank left. If you have ground that much off your round nose tool in 1 year, then you must've worked your way through several tons of brass stock! If what you are really saying is that you haven't got the hand grinding skills, or a suitable bench grinder, to do the job, that is a very different matter! Spending time mastering tool grinding is well worthwhile. >I found a web site that sells carbide inserts for the Taig >(Plastools.com out of Bellingham, Washington). >I can't seem to get a good finish with these. Lots of tool >chatter and it looks like I'm cutting threads on the brass. I suspect part of the problem (having looked at their website) is that these are double sided inserts (six cutting edges from a triangular insert) & the tip is angled slightly downwards to give the necessary clearance angle (i.e., these are "negative rake" inserts). These take rather more force to cut correctly than "positive rake" inserts like the CCMT series (see below), which may help explain why you are having problems. >I've tried different speeds, feed, etc. with no luck. The old, dull HSS >still cuts better than the new carbide. Am I doing something wrong I use replaceable carbide tipped tools for brass - mostly because I am too lazy to grind HSS tools - and have had no problems at all. The inserts I generally use are Sandvik Cormorant CCMT 06 02 (tip radius of 0.2mm); these work great on brass & give a good finish. 'Fraid I can't point you at a Canadian supplier. Some important things to improve the finish: - The cutting edge of the insert must be at centre height; - You have to feed the tool across/along the work slowly and/or use a high spindle speed; - Use a very light final pass. Regards, Tony ------- Date: Tue, 19 Nov 2002 19:26:09 -0500 (EST) From: Paul Anderson Subject: Re: lathe tools On Tue, 19 Nov 2002, bursulescu wrote: > P.S. I live in Canada so obtaining separate tools from Taig is > somewhat of a hassle. First thing, you can head down to your local branch of Acklands Grainger, walk up to the counter, and ask for a couple of 1/4" high speed steel toolbits. If they don't have them in stock, they can order them. It sounds like you are running WAY too slow, carbide wants to go fast, fast, fast. I suspect you are off centre height - does it take a lot of pressure before the tool will start to cut? You can check the height of the tool by the tailstock. Also check the insert. With carbide insert tooling, especially the cheap tools, make sure that the insert is being held firmly in the holder. If you can wiggle it, it's too loose! Paul Anderson ------- Date: Tue, 19 Nov 2002 17:29:55 -0600 From: "Don Feinberg" Subject: Re: lathe tools Also -- Enco has a lot of appropriate "brazed" carbide tools (www.use-enco.com) They have had, for the last 6 months, sets of (imported) tools like: 6 of AL 6 of AR 4 of BL 4 of BR plus a few Cs and Ds -- total of about 20 tools for $30. They're sold in 1/4", 5/16", 3/8", and 1/2". Don Feinberg ------- Date: Wed, 20 Nov 2002 14:59:31 -0000 From: "bursulescu" Subject: lathe tools Thanks for all your quick responses regarding carbide inserts on brass. I did a quick test last night and found the tool to be at the correct height. One thing I didn't check before was the gib. There was slight play on the cross slide. After the adjustment I fiddled with the speeds. I found number four (one being the slowest) to be the optimum speed. I think I was being too shy with the depth of cut. The problem is now solved. Carbide likes to go deep. The results were remarkable. Thanks again. I'll be back. P.S. I live in Vancouver, British Columbia. ------- NOTE TO FILE: This thread was put in the Turning Brass text file because brass sometimes presents unique problems. There is a great deal more information about the parting off process in the Parting Off text file. ------- Date: Fri, 11 Apr 2003 12:01:48 -0000 From: "silverwaterh" Subject: parting off brass with a cut-off tool Question about parting off with cut-off tool a 30 mm (~1 3/16") dia brass rod. I'm a beginner machinist. just received my Sherline equipment a month ago. I am very satisfied. I need two fly wheels each 5 mm (~5/16") thick. The cut-off tool chattered and dead stopped the chuck three times by the time I got to 5 mm (3/16") depth. The cutoff tool is new and sharp. The two "stops" I didn't use oil, since I read in some books brass should be cut dry, then I did use cutting oil; there was no difference. The parting cut-off tool was 19 mm (3/4") from the chuck and only extending 2 mm past the half point of diameter. I stopped parting off, of course, so as not to damage my new Sherline.(I didn't). I used a hacksaw to finish the job then refaced that side. I'm sure I made a number of beginner's mistake. Please, I would like some advice from you experienced machinist. Thank you for your time. Howard Silverwater ------- Date: Fri, 11 Apr 2003 07:28:34 -0500 From: "Nance, Tom" Subject: RE: parting off brass with a cut-off tool Hi Howard: Just go slow and use lots of fluid. Slow means both feed and rpm. On a piece that big, I would run between 80 and 120 rpm. As for the feed rate, keep both hands on the wheel and try for a very steady, very slow feed. When you start and stop the feed, a little ledge is created on the face of the work where the last chip broke off. Then when you start to cut again that ledge is going to slam into the top of the tool and may seize the lathe. On the other hand, if while feeding you hear the machine begin to labor, back off a bit and let it come up to speed again and then feed back into the slot being cognizant that you are going to encounter a bump. Very slowly work thru the bump and then continue on. If you notice that the machine is *always* laboring, check your setup. You may have the tool at a slight angle (not perpendicular to the work) or it may be below the center line of the spindle. It takes a bit of practice to get it down, but don't worry you'll catch on very quickly. That's the fun of machining. I get a kick out of all these guys who've never turned a thing in their lives and buy a CNC machine to start their new hobby. A CNC machine is great, don't get me wrong, but it will only do exactly what it is told to do. You can't tell the programs what material you are cutting and it figure out the best way to go about doing it. Hands on experience is the only teacher of feed rates, milling types (up or down), clamping techniques, and proper movement sequences. Oh well. Have fun and learn as much as you can. Tom Nance Corpus Christi, TX ------- Date: Fri, 11 Apr 2003 12:14:10 -0400 From: "Carol & Jerry Jankura" Subject: RE: parting off brass with a cut-off tool Hi, Howard: I'm also kind of new to machining, so don't take everything I say as gospel. But, I'd probably face off one side of the rod, then take it off of the machine and cut it a little over sized on a band saw (or even a hack saw), remount the piece with the 'cut' end out, and face it off to the 5mm dimension. Then, I'd drill the center. Jerry ------- Date: Fri, 11 Apr 2003 09:24:31 -0700 From: "Dave Hylands" Subject: RE: parting off brass with a cut-off tool I ran into a couple of interesting parting problems that I showed here: http://www.davehylands.com/Machinist/Projects/Inkle-Loom-Screws/Sm all/12-Weird-Parting.html Since that URL is almost certainly going to get broken up, you can also click on this link: http://tinyurl.com/9bed Look at that picture and the 5 following. The finish on the finished washer is what I got from the parting operation. I didn't use any lubrication, and the stock was about 3/4" in diameter. Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Fri, 11 Apr 2003 13:40:18 -0400 From: "Kevin Martin" Subject: RE: parting off brass with a cut-off tool I've had a similar problem--somehow the work moves lengthwise in the chuck while doing a cutoff. In addition to the tip of the tool cutting inward, one entire side of the tool is cutting as well as the work spirals into it. The caption on your photo says the part is getting "sucked out of the chuck" but the shape of the stock left in the chuck (which has a bump on its end) would indicate that the work was getting pushed *into* the chuck, not *out* of it, would it not? Or am I musunderstanding how the bump formed? I usually find that if I back out the tool and restart (repositioning it to match the new work position), it runs straight the second time (one corner takes off the "bump" left from the first pass, and once I reach the depth where I abandoned the first pass, everything goes OK from there. One cut surface is clean, the other has a round platform in the middle. The fact that the second pass works would tend to indicate this is a self-feeding problem--once the side of the tool starts cutting, it "pulls" the work into itself. This would further imply that the problem can be started off with a microscopic deviation from squareness of the tool. Kevin Martin ------- Date: Fri, 11 Apr 2003 11:17:29 -0700 From: "Dave Hylands" Subject: RE: parting off brass with a cut-off tool Hi Kevin: What would happen, is I would start to part and the parting blade would get pushed away from the chuck. If I pulled the parting blade back out and allowed it to straighten, that's where you could tell the part was being pulled out of the chuck. What made me realize what was happening is that after doing 3 or 4 of these parting operations, I could see a gap between the base of the piece and the face of the chuck. When I put the round piece of brass in, I had it butted up against the face. This was further confirmed when I put the tailstock against the piece, all parting problems disappeared. If the work was being pushed into the chuck, then the tailstock wouldn't have helped. I don't understand why the shape of the piece turned out the way it did, except that the blade was being bent. I also repositioned the parting tool (by moving the cross-slide) several times as well. I haven't parted anything since that particular work, so I haven't had much time to play with things further. Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Fri, 11 Apr 2003 18:57:43 -0000 From: "kimvellore" Subject: Re: parting off brass with a cut-off tool I have had the same problem, I start cutting using the cut off tool halfway through when I pull back the blade and try to continue again I see the blade moves right (away from the jaw) so I move the blade a little back and continue. I later realized that this happens if the blade is slightly angled. Kim ------- Date: Fri, 11 Apr 2003 12:31:02 -0700 From: "Wm. Dubin" Subject: Re: Re: parting off brass with a cut-off tool I solved 95% of my cut-off toll problems by using a thicker cut-off blade. On my 6" lathe, I'll use as blade as thick as 1/8". I also use carbide tipped blades, and if the part is over 1" thick, I use cutting oil. Make sure the tip is just below the center line, and use a SLOW speed. Wm. ------- Date: Fri, 11 Apr 2003 23:13:56 EDT From: catboat15x~xxaol.com Subject: Re: Re: parting off brass with a cut-off tool > Make sure the tip is just below the > center line, and use a SLOW speed. One of the tricks in using cut off tools is to feed faster than you think you should. Make sure the blade is sharp and for brass no rake at all. If you are too bashful about feeding you will get chatter, hang ups etc. Keep the feed going by using two hands and don't pause while cutting. You can usually tell from the sound and the appearance of the chips if you are doing it correctly. ------- Date: Fri, 11 Apr 2003 23:16:45 -0700 From: Keith Green Subject: Re: parting off brass with a cut-off tool Dave, You will run into that problem when the chuck cannot hold the part tight enough. Shouldn't happen with a 4-jaw but will often happen with a 3-jaw. On a large machine, I often have the work pull out on me when using a steady. This is caused by not having the steady on center with the spindle. I expect the same phenomenon causes both problems. The chuck cannot keep the piece from wobbling and when it wobbles, the workpiece either "works" in or out of the chuck. In in your case, out in mine. When you put the tailstock in, it stops the wobble. ------- Date: Sat, 12 Apr 2003 12:34:37 -0000 From: "Bill McKillip" Subject: Re: parting off brass with a cut-off tool In sherlinex~xxyahoogroups.com, "silverwaterh" wrote: > Question about parting off with cut-off tool a 30 mm (~1 3/16") dia > brass rod. I'm a beginner machinist. just received my Sherline > equipment a month ago. I am very satisfied. Howard Silverwater Hi Howard: I had a great deal of difficulty too with parting off when I first got my Sherline. The biggest difficulty is speed - in two ways. First you have to use a bold feed in on the cross-slide and a very slow rotation. Unfortunately, you have to practice the cross-feed and develop a touch, because it is really surprising how much you have to feed in. I was too lazy one time to put the motor back on after threading, and tried parting off just by hand turning the lathe with the threading handle. To my surprise, the parting off went very smoothly at this very low rpm and I was able to feel how much feed in was required. If you have the threading kit, you might want to try this to see how it feels. Your part, at over 1 inch, is getting pretty big for the minimum speed of the lathe. At that diameter, the surface speed is fairly high, so you have to have lots of lubrication and a steady feed. The manual says to always use lubrication with the parting tool and I take that as gospel. When you have the feed right, the metal comes off in a smooth, flat, continuous chip that looks like Christmas tinsel. The sound is quite distinct too, a nice and smooth peeling sound. If you get any squeaking or ticking or grinding, pull out and re-attack. Getting the tool exactly perpendicular to the work is extremely important, but not too difficult. Line up the left edge of the tool with the faced-off end of the work so that there is a tiny gap. Feed it back and forth until you can see that it keeps exactly the same gap. Practice makes perfect,too. I sacrificed a couple of inches of steel, aluminum and brass in a practice session. It was well worth it, I don't hesitate to part off now. Safey - I disagree with using the tail stock when parting off. The parting tool pushes across the work quite strongly. With the part supported at both ends, the narrow parting slot can pinch the tool leading to disaster. If the work needs to be supported, use the steady rest between the headstock and the place you are parting off. Bill ------- Date: Thu, 3 Jul 2003 23:56:35 EDT From: HUNLEY31x~xxaol.com Subject: Steady rest question Well, I'm getting ready to use my steady rest for the first time. Question is Can I use the brass 'fingers' against a brass casting or do I have to make a steel ring and mount it on the casting for the steady rest to run on. I'm boring a hole out and think the work will be under a lot of stress. Any pointers will be appreciated. Thanks, Larry ------- Date: Fri, 4 Jul 2003 00:02:25 -0400 From: "Rigrac" Subject: Re: Steady rest question If non-marring of surface is of importance then you should mount a ring to casting. If casting is rough (not at finished size then you can run steady on it and then remove marks when taking finish cut on O.D. Ron ------- Date: Fri, 4 Jul 2003 13:28:04 -0400 From: "mertbaker" Subject: Re: Steady rest question The lunette will leave a polished ring around the work. Use lube. Mert ------- Date: Mon, 15 Sep 2003 19:25:20 -0000 From: "Tom Munroe" Subject: Tool Chatter [TAIGTOOLS GROUP] My name is Tom Munroe. I just joined your nice group here and it's real great being able to read all the wonderful tips on using my Taig lathe. I've had it for many years but never really got to use it untill recently.I've been laid up with arthritis in my legs and have been off the job for a year so far, maybe permenantly :-( Well enough of the bio, my problem is I have just discovered the abilities of my standard Taig with brass work. I've been making some simple knobs and such for the lathe itself and keep getting into tool chatter. I'm as I said rather new at this and would love to know how to stop this annoying problem. I don't have much money anymore to buy fancy tools or much of anything for that matter but I'm sure you all can give me some advice. I'm eager to learn but can't afford to buy any special books so here I am at your mercy . Thanks for any help or directions. Glad to be a part of the group and maybe I can give some advice in my special areas of interest, amateur astronomy, wooden model ship making, wood pen making (a new hobby for me as well). Thanks Tom Munroe ------- Date: Mon, 15 Sep 2003 15:36:56 -0400 From: Stan Stocker Subject: Re: Tool Chatter Hi Tom, Most or all of your tools probably have 7 or more degrees of top rake. Use a tool with zero top rake for brass. Things will smooth right out! Easy to grind from 1/4 inch blanks, just do front and side clearance as usual, for the tip radius as you with, and leave the top of tool alone. Cheers, Stan ------- Date: Mon, 15 Sep 2003 10:01:15 -1000 (HST) From: Tom Benedict Subject: Re: Tool Chatter Lemme second what Stan said. Brass seriously likes to be presented with a cutting edge with no top rake at all. I've cut with 5 degree rake cutters, but the flat ones really make a better surface. Some other thoughts on chatter: Hone your lathe tools. Tools fresh off a grinder will work on a bigger, beefier lathe, but the Taig really needs razor sharp tooling in order to shine. A good "at the bench" test for a lathe tool: Try to scrape the top of your fingernail with the cutting edge of the tool. If it just skips across or digs a furrow, it's in need of sharpening. If it makes a nice cut with shavings, it's good to go. Support the work. If you have more than about two diameters worth of work sticking out of the chuck jaws, it may be prone to flexture. For knobs this probably won't be a problem. They're pretty stout. But if you're turning shafts and such, support the outboard end of the material with a tailstock. Even with tailstock support, really really thin work will still tend to flex. This is what follower rests are for (though I don't have one.) If you still get chatter, even with sharp tools and good tool geometry, and a well supported workpiece, look at your speeds and feeds. It may sound a little counterintuitive, but if you get chatter decrease spindle speed or increase feed rate. Both of these serve to take a heavier cut and make a heavier chip. Just had a thought... If you're getting chatter and suspect it might be flexture in the workpiece, there's a way to find out: Take a cut along the length of the workpiece. At different distances from the headstock, you'll get different kinds of chatter. The sound will be different, and the resulting pattern on the material will be different. If you get that kind of chatter, nine times out of ten it's flexture. Tom ------- Date: Mon, 15 Sep 2003 10:33:48 -1000 (HST) From: Tom Benedict Subject: Re: Tool chatter On Mon, 15 Sep 2003, Tom Munroe wrote: > That would be fine if I knew what you mean by top rake.I guess > I didn't make it very clear but I know very little so far about metal > turning or the tools it requires.I have good sharpening equipment I > use for my woodtools but just don't know all the terms yet.Could you > help out with a bit more of a discription as to what you > recommend.Sorry for being so green :-)Thanks. Hey, no apologies for learning. It's got to start somewhere. As for top rake...I don't remember if this one mentions it specifically by name, but here's a good link for hand-grinding tools: http://www.sherline.com/grinding.htm Another one is in the Files area on this group, a file called: Stantoolgrinding.txt It's a guide to tool grinding from Stan Stocker, and is also an excellent reference. This deals heavily with tip radius, something that bit me repeatedly when I first started using my Taig. Other grinding guides mention it, but don't really go into the why. I like this guide. Take a look at those two. If they don't answer all your questions (nothing ever answers ALL the questions), let me know. Tom P.S. Just had a thought. You mention wood tools... If you've got a wood lathe, think of a brass cutting tool as being similar to a scraper. The tool is held so the top of the tool is roughly perpendicular to the side of the work. That's zero top rake. ------- Date: Mon, 15 Sep 2003 10:49:08 -1000 (HST) From: Tom Benedict Subject: Re: Tool chatter Another thought: If you're looking for information on machining in general, and in using your Taig in particular, definitely drop by Nick Carter's web site: http://www.cartertools.com Nick's got lots of good info on his site, as well as a VERY comprehensive list of links. He updates it frequently, so there's almost always something new to look at. Tom ------- Date: Mon, 15 Sep 2003 16:59:48 -0400 From: Stan Stocker Subject: Re: Tool chatter Hi Tom, Nothing to be sorry about, we all started out in this knowing diddly! Here's the short answer: For brass, just grind the front and side of the tool to around 5 degrees, leave the top of the cutter alone, and finish up by honing to a good finish - mirror finish is nice, very smooth is likely good enough. Round the tip of the tool a bit, maybe using a 1/16 inch drill bit as a guide for a nice starting point on the radius to aim for. Here's a bit more than you may want, but will hopefully get you off on a start: Probably the best place to start is on the Sherline site, the description of grinding lathe tools is the best getting started guide I know of. It does have several errors or omissions, particularly the mention of water dunking. HSS blanks should not be quenched from red heat, although simply cooling off a tool that's getting uncomfortably warm is fine. http://www.sherline.com/grinding.htm On to terms: BTW - I'm assuming a plain old toolpost here, with no tricks of wiley old shop rats applied. There are lots of tricks around, but we'll stick to plain vanilla for the time being. I'm going to stay really simple on angles, a good metalworking book will talk about chip loads, cold welding, chip forming and breaking, lots more than you are probably ready for. Clearance angle: Just as a knife of chisel won't cut when laid flat on the surface, a lathe tool can't cut unless the cutting edge can get into the work. As we can't tilt the lathe cutter as we can a knife, we grind the side and front of the tool so the top edge contacts the work only, giving the same effect as tilting a knife blade into the work. By grinding the front and side surfaces of the cutter so they are relieved by 5 to 7 degrees, the cutting edge is well supported so it doesn't chip, but the tool can cut rather than rub. Rake: The angle of the top suface of the tool with respect to the lathe centerline/ point of tool contact. This is sort of an ad-hoc description, for the Taig you can simply consider this to be how many degrees is the top surface of the tool ground away from the cutting edge. Steel likes around 7 degrees, aluminum likes 12 or more degrees, and brass likes zero. Basically, does the material chip, chisel, or slice better :-) The rake plus the clearance angle equates to how acute the angle that forms the cutting edge is. Steep rake slices, up to the point that the edge becomes too delicate to hold up under use. They also tend to dig into materials that like to self feed, such as your brass. Dig, catch, flex, break loose, repeat. Chatter city... If you look at Figure 10B on the Sherline site, The view labelled "side" shows the front clearance nicely and somewhat shows the top rake, the "front" view shows the side clearance nicely. Why Sherline didn't fill out the information with the standard terms for lathe tools is beyond me, why "hook" is used in place of top rake is a mystery :-) Smaller lathes can't get away with the same tools as larger ones, might as well learn to grind cutters now. Always hone the surfaces after grinding. You can use a small hobby style stationary belt sander instead of a grinder, just use care. You want to always be grinding in a way that you are removing material in a direction perpendicular to the cutting edge. Cheers, Stan ------- Date: Sun, 14 Dec 2003 22:17:17 -0000 From: "montanaaardvark" Subject: Milling Brass - First Time I'm trying my hand at what's supposed to be "free machining" brass for the first time. I'm trying to square up a 4" square piece of 1/2" thick stock, and I find that no matter how fast I feed it I get tool chatter. Well, that's not exactly true. I'm using TurboCNC to drive my CNC 5000 mill, and it goes a few inches per minute. That said, unless I step in tiny steps, like 50 mils, I get chatter. The motor speed has no effect. I've been taking fairly light cuts, 5 to 10 thousandths (across the 1/2 face). Climb milling seems to work better than conventional milling. The cutter is a 3/8 end mill in the Sherline end mill holder. Do you need to machine this brass at 1/4" inch per minute? Less? Thanks, Bob ------- Date: Fri, 31 Mar 2006 16:35:09 -0000 From: "countrybj2006" Subject: What is the proper tool to get a smooth cut? [atlas_craftsman] When turning a cannon barrel with brass, what is the best tool to use to get a smooth cut? Pointed, round, ect.? Also what is the proper way to mount the tool? At an angle ? straight into the work? I do use 320 grit emery-clouth to buff the barrel but would like to get a better finish from the cutting tool. ------- Date: Fri, 31 Mar 2006 18:33:20 -0500 From: "Joe R" Subject: Re: What is the proper tool to get a smooth cut? I've found that a round tipped HSS tool stright in works best for me. However I've never done a lot in brass. Just now there are 3 lathes in my basement and I have tried brazed carbide tools in my SouthBend "heavy 10" on steel and found a round tipped HSS blank I ground myself works better. Joe Romas ------- Date: Fri, 31 Mar 2006 22:48:00 EST From: n8as1x~xxaol.com Subject: Re: What is the proper tool to get a smooth cut? a large radius round point works well .zero to slight neg.rake .....also a pointed tool w/ a flat on the end at least double the feed rate ... make ur finish cuts .015 or LESS ! ......005 works well for me w/ a sharp tool on steel a shear grind bit gives the best finish for me followed by a abt a 1/32 flat on a pointed tool w/ plenty side & back rake... a shear bit is ground w/ a large radius ,maybe 2 in. on the end & the grind is made w/ the bit rotated so the round edge is applied at abt a 60 deg angle TO THE t/stock ,cuttinting to the right...there is clearance ground behind the bit & it is not critical that it be applied on center ...u have essentially a monumental negative rake angling up , left to right ,when cutting to h/stock ...once u play w/ this , it will be the grind of choice ...005 or less doc best wishes docn8as ------- NOTE TO FILE: There was an interesting conversation in the Sherline group about drilling small holes in brass, and has been put into the Drilling Tips file starting Sep 14, 2006. ------- Cutting off yellow brass [atlas_craftsman] Posted by: "countrybj2" countrybj2x~xxyahoo.com Date: Sat Apr 5, 2008 7:04 am ((PDT)) What speed should I use to cut off a 2" piece of yellow brass? I have an american style post and was using the cross slide to feed the cutoff tool into the brass. It wanted to catch and bind; was scared I would break the tool or lathe. I had the tool right at center. May have been turning too fast. ------- Re: Cutting off yellow brass Posted by: "countrybj2" countrybj2x~xxyahoo.com Date: Sat Apr 5, 2008 8:02 am ((PDT)) James Walther wrote: > What speed were you using and did you have the carriage locked? The carriage was locked and I was using the back gears to slow down the speed, but not sure what the speed was. It was slow but maybe not slow enough. ------- Re: Cutting off yellow brass Posted by: "Jay Greer" redwitch1x~xxearthlink.net Date: Sat Apr 5, 2008 8:16 am ((PDT)) One of the problems with the Atlas 618 is that it does not have enough rigidity and mass to allow high speed cut off work in brittle metals such as brass. Although I have the biggest tool blocks available and use carbide tipped cutters, I find that I must resort to the slowest back gear speeds combined with slow feed in order to do cut offs. The tool also needs to be dead nuts on center as well in order to prevent hogging. Cheers, Jay Greer ------- Re: Cutting off yellow brass Posted by: "Charles Gallo" Charliex~xxTheGallos.com Date: Sat Apr 5, 2008 8:23 am ((PDT)) Guys: You're going TOO slow - read what Teenut had to say here: http://yarchive.net/metal/parting_off.html I cutoff brass at the same speed I turn it - which is somewhat limited by the counterbore I run in one operation - the 5/8 bar is turning at around 800 rpm if I remember right - set my speeds long ago, and have not changed them. 90% of what I have been doing is this one job - if I had the space a screw machine or a chucker would be added to take this job over, and I could get back to doing hobby stuff. Setting up/breaking down this job is enough that I rarely do hobby stuff anymore. 73 de KG2V ------- Re: Cutting off yellow brass Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Sat Apr 5, 2008 8:37 am ((PDT)) Brass has that "catching" effect. You want zero top rake on the tool, but maybe you should use a hacksaw, bandsaw, or whatever you have instead of trying to part it on the lathe. A really rigid lathe could probably handle it, but the bed flex in the Atlas makes it more difficult. There are ways to adjust the lathe to minimize such effects. One thing is to make sure the carriage and compound rest is as close to under the cutting area as possible. If the cutting tip has a large overhang from the center of the compound swivel, a tilting motion can develop that greatly worsens the binding/digging effect. If this is solid round stock, that means you need over 1" of tool overhang to fully part off a 2" bar. That is a lot of overhang. Depending on the thickness of the cutoff tool, it may or may not handle it well. Another trick is to put a little notch in the top of the cutoff tool, running parallel to the length of the blade. This tends to curl the chip inward, reducing binding of the curly chips in the kerf. Brass may not make those rolled-up chips, so it may not matter on that. It definitely helps on steel and aluminum. Jon ------- Re: Cutting off yellow brass Posted by: "Ron Shaw" RS0255x~xxaol.com Date: Sat Apr 5, 2008 9:12 am ((PDT)) Atlas' Lathe Operation manual says cut yellow brass at 200 sfm (surface feet per minute). On a 2" piece that would be 400+rpm, well above anything you can get in back gear, probably more like step three (counting from the largest spindle pulley)of the countershaft/spindle belt. A rule-of-thumb formula for determining rpm is: (4 x sfm)/dia.of workpiece=rpm With yellow brass at 200 sfm this yields: (4x200)/2=400rpm As the diameter of the workpiece reduces during the cutoff procedure, you theoretically should increase rpm. At 1" diameter for example the rpm should be 800. I probably would not do this myself, and probably just keep chugging away at 400rpm. I use a .040 width cutoff blade in a KRF toolholder and had very little problem with cutoff. You DO have to make sure the cross slide is snugged down well, as if it tilts even a little bit the blade will twist and start cutting off-kilter, resulting in a dished cutoff face. RonS. ------- Re: Cutting off yellow brass Posted by: "azbruno" azbrunox~xxyahoo.com Date: Sat Apr 5, 2008 2:53 pm ((PDT)) Hey, someone else with a KRF tool holder... I really like mine! Anyway, don't forget to also snug down the compound as well as the cross slide. On my 618, I use one of the four gib screws for a lock and if I'm not actually using the compound, I'll tighten it right up. You wouldn't believe how a compound can work it's way out a thou or two, and you may never see it. ------- Re: Cutting off yellow brass Posted by: "n8as1x~xxaol.com" Date: Sat Apr 5, 2008 7:42 pm ((PDT)) first off, use a high speed tool, (sharper ,requires less force..) & put some NEGATIVE rake on it ......plain turning w/ positive rake will induce digin, never mind cutting off...also turn the rocker REST upside down & shim up to proper ht.... the flat base is way more ridgid...it is possible w/ multiple holders to use a flat bottom rather than a radius & adjust the center ht. by moving bit in /out after a proper size lantern base is made.(flat),since it is held at an angle... ..then all u do is switch holders & u r there....same can be done w/ multiple openside blocks bolted down w/ a t nut /base. best wishes docn8as ------- Re: Cutting off yellow brass Posted by: "LouD31M066x~xxaol.com" Date: Sun Apr 6, 2008 10:17 am ((PDT)) When you have everything dialed in right...brass cuts like butter....in fact the first time I tried it I had too much overhang and it popped right out of the chuck like a stick of butter. Louis ------- Re: Cutting off yellow brass Posted by: "countrybj2" countrybj2x~xxyahoo.com Date: Sat Apr 5, 2008 9:33 am ((PDT)) I think I may have my cut off tool mounted to far from the stock that I am cutting, thus causing twist in the tool and then hogging. Will try to move closer to my work and see if that helps. Thanks everyone for good info. ------- Re: Cutting off yellow brass Posted by: "catboat15x~xxaol.com" Date: Sun Apr 6, 2008 7:37 pm ((PDT)) Brass requires a negative rake, if you try turning with a tool shaped as you would for steel the positive rake in the tool would dig in and pull the tool deeper into the cut. Then too, the word "brass" covers a whole lot of sins. There is leaded brass screw machine stock which is made to be machined on automatic screw machines and machines very well on our lathes. Then still technically brass are alloys that are difficult to machine and the chips are sticky and build up on the tool's cutting edge, want to chatter and are generally a pain. Then among all the operations we expect our lathes to do is parting off, probably one of the most difficult to perform. One trick I use often is to feed in the parting tool about the thickness of the tool, retract and cut alongside the first cut to create a wider groove so the chip cannot clog the cut. Keep going step wise in this manner. Don't let anyone on this list know, but at times I grab a hack saw and part off a chunk of work where the finish and exact length are not important. John Meacham from the high deserts of Calif 12 inch Atlas lathe, mini mill, HF band saw and a rusty file. -------