Lots of user tips for parting off successfully. Parting off metal objects (being turned on a metal lathe) looks like it should be easy, but the conversations here try to answer many problems that are typically encountered by new machinists. Find other ideas and tips in the file here called "Cut or Saw Metal". 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. =========================================================================== Date: Sat, 31 Mar 2001 01:15:34 EST From: LADDERBARx~xxaol.com Subject: PARTING TROUBLE I'm having a problem parting off on my 12 late model atlas. The parts are less than satisfactory and if I I use an insert tool it will brake. Here's a run down I have a phase 2 quick change tool post, the tool bit was aligned with the chuck (square) with minimal tool sticking out. The tool was aligned with a center in the chuck on center, then about .025 above. The saddle has about .002 clearance from the bed and every thing else seems tight. When parting I lock the saddle down and hand feed the carriage. I've slowed the rpm's, used cutting fluid tried soaking the part with WD 40 but I'm still having problems. I hope what I've written makes sense any help in this matter would really be appreciated (and save me some money). Happy Chip Making Mike ------- Date: Sat, 31 Mar 2001 04:41:18 -0500 From: "Dr. Robert Harms" Subject: Re: PARTING TROUBLE The standard parting tool size that fits the Phase II defualt parting tool holder is too small and light weight for any type of work beyond the thinnest aluminum. I bought an Armstrong cut off tool and modified it to fit in the normal tool holder. Works much better ------- Date: Sat, 31 Mar 2001 07:13:55 -0600 From: "Dana Zimmerman" Subject: RE: PARTING TROUBLE The best thing you can do for parting is turn the tool upside down. Seriously. Most lathe operations have an inherent engineering problem, in that the cutting forces tend to flex the tool and tool post down and forward into the work piece. This is especially bad for parting, which is a grabby kind of cut and tool. This strategy also reduces the very real danger in parting. The wisest machinists with the "modern" lathes that have a cross slide that is long enough, put the parting tool behind the work piece and upside down. In this arrangement, when the tool grabs, the tool post flexes away from the work, and releases the pressure on the tool rather than making it worse. It will work with the tool in front of the work, but in this case you have to turn the lathe "backward" which could unscrew the darn chuck. My father apprenticed as a machinist in the 1920's and has told me that when he started out, every machine shop had a couple of guys with eye patches in the manner of Long John Silver. The cause was usually the parting tool. When a parting tool grabs, and the tool post flexes, the tool digs in and if the lathe has the power, the tool will break in such a way that it sends a triangle of high-speed steel, at high speed, exactly at the right angle to get the machinist leaning over the lathe in the eye. Wear your safety glasses! ------- Date: Sat, 31 Mar 2001 06:20:49 -0800 From: "Larry Bailey" Subject: Re: PARTING TROUBLE I read the other replies. Good advice. In my limited experience I have found that the tool should be right on center. If the tool digs in a little, it will decrease engagement with the work instead of increase it. I also usually part with the power feed. Seems to be smoother than I can hand feed it. Good luck, Larry ------- Date: Sat, 31 Mar 2001 15:45:13 -0000 From: STYSx~xxMINDSPRING.COM Subject: Source codes & advice on cut-offs Larry, I have a document on my home computer that has source codes for Craftsman items. I found it on the internet last year. Email me at stysx~xxmindspring.com, and I'll email it to you if you still need it. Also, my machinist friend taught me that when you are using a cut-off tool, try to use one narrower than the groove you are trying to create. That way you can make multiple plunging cuts, moving your tool left or right between plunges, and not have the material grab on the sides of the tool and cause a crash. I have used his advice with my Phase II holder and with my lantern type holder without any problems in grooving cold rolled steel, bronze and aluminum. I also make it a practice not to cut all the way through with the cutoff tool when I'm making an item like a thrust washer. The last bit before it breaks through, I'll use my hack saw. Wilford always tells me to play it safe, take the time and use the saw! My friend still has both eyes, and all of his fingers (minus the end of one thumb, and he has been a machinist for close to 40 years! Hope this helps Rick Stys Apex NC Craftsman/Atlas 12X24 ------- Date: Sat, 31 Mar 2001 13:40:08 -0500 From: Jude Miller Subject: Re: PARTING TROUBLE Here's a posting by the late teenut (Robert Bastow) on the subject from rec.crafts.metalworking. Best, Jude Miller >>> Most people treat the pre-ground HSS parting blades as a finished tool, ready for use. It is NOT! No more than a ground, square, HSS tool bit is a ready to use tool. Parting tools NEED side clearance. This must be ground into the blade before use. When re-sharpening has reduced the length of useable blade below the radius of the piece to be parted off..start again! Snap or grind off the short end and regrind side clearance on a new section. Fer Chrissakes..new blades are cheap enough to buy! Lets belay all this crap about whether the blade should be at, above or below center. ANY and EVERY lathe tool should be set at dead center height..PERIOD. If you get better results by not doing so..you are doing something WRONG and need to re-examine the geometry of your tool bit. Unless you are parting off SMALL diameters, and wish to reduce or eliminate the center "Pip", the nose of the tool should be ground SQUARE to the body. Any angle to the nose will, invariably, deflect the blade to one side, during deep cuts..resulting in binding, rough finish, non-flat surfaces or breakage. More importantly, an angled cutting edge produces a chip WIDER than the slot..how the hell do you expect this to escape freely from the cut? Better, even than a square grind, is a slight radius, or as I use a broad "Vee" shape to the nose..This flows the chip in on itself, producing chips that are noticeably narrower than the cut and which clear the slot easily. If you want to add belt to suspenders, use a tiny mounted point to grind a shallow, radiused groove LENGTHWISE in the top face of the tool. Examine a carbide, inserted parting tool tip, to get an idea of the best geometry to achieve. Chatter is reduced by INCREASING feed! Power feed will give best results. Rigidity of the entire set up is next to Godliness! Lock all slides not in use. Normal cutting speeds are the rule..Reduce ONLY if your rigidity is suspect. Reduce overhang to a minimum..both in the tool setup and the workpiece. Avoid Lantern type tool posts and Armstrong tool holders like the plague. Especially the angled parting tool holders..the worst abomination ever foisted on unsuspecting machinists. If you can't afford a rigid tool post..MAKE one! Rear mounted toolposts have definite advantages..Deflection of the tool or workpiece tends to lift the cutting edge OUT of the cut, rather than forcing it deeper...this by dint of the geometry involved. Mounting the parting tool upside down, in the front tool post, and running in revers, has the same effect. This same arrangement works wonders with broad form tools too. Part off as close to the chuck as possible. If a long overhang is unavoidable, or the parted off piece is relatively long..use GENTLE pressure from the tailstock to prevent whipping and chatter. Remove this just before final breakthrough or you may get a jam up. Judicious use of a fixed steady, a wedge of wood 'twixt toolpost and job, or, (dare I say it,) a well lubed hand, (NO GLOVES PLEASE!!) will also help to reduce chatter in these circumstances. Lubrication is a MUST except on free cutting brass and MAYBE good grades of grey iron. Drip feed or flood lubrication..matters not. Just bear in mind that a happy parting tool sounds like frying bacon. The instant it starts sounding grouchy..add more lube. Happy partings. teenut <<< ------- Date: Sun, 3 Jun 2001 13:57:41 -0500 (CDT) From: dswrx~xxwebtv.net Subject: Old, but worth repeating... Hi Lathe Lovers, Yesterday, I re-learned an old lesson; When "cutting off" ALWAYS put the tool point on the EXACT lathe center! Not above, not below, or eyeball it and get it "Close enough for government work" (what ever that means). I was machining brass to make washers for my crossfeed vise. I tried cutting off the little slices and stalled the spindle on my Craftsman 6". (no i was not using the backgears). The tool dug in, tried again, same thing. I gauged the point and found it was just above (0.10 ~ 0.20") the lathe center. I set the tool point to the exact center (point of 60 degree dead center in tailstock). Now, it cut the brass like butter (or margarine... if you are on a diet)! Nothing new, but little things are overlooked by ole guys like me. 8-) Leo (of course, i used cutting oil) ------- From: sleykin... Date: Tue Aug 14, 2001 8:28 pm Subject: Re: [atlas_craftsman] cut off tool problems/taper attach. wanted. A great tip from the recently departed Teenut ... Grind the parting tool with appropriate back rake and a square tip. Then with the corner of the wheel cut a shallow "V" in the center. This tends to cause the chips to turn in on themselves, giving more chip clearance and a cleaner cut. Other than that all the same old stuff applies .. lock everything down that dosn't have to move and feed rather aggresively. If you are using the lantern toolpost consider something more ridgid. I have an AXA style QC holder on my 12" and have no trouble (most of the time) parting off anything I can cut. Good Luck Glenn ------- From: James Meyer Date: Tue Aug 14, 2001 8:45 pm Subject: Re: [atlas_craftsman] cut off tool problems/taper attach. wanted. >Hi, I just joined the list. I am a maker of custom french horns and >therefore use my 12" Craftsman lathe to cut brass bar and tubing. Does >anyone have any suggestions on cut off tooling? I get a bit of chatter >etc. The shape of the business end of the cutting tool has a lot to do with how smoothly you can cut brass and copper and alloys like that. A cutting tool that works perfectly for iron and steel is exactly the *wrong* shape for brass. Brass cuts best for me if I use a tool with no relief under the cutting edge and very little "rake". The action is more like scraping rather than cutting. Jim ------- From: catboat15x~xxa... Date: Tue Aug 14, 2001 8:49 pm Subject: Re: [atlas_craftsman] cut off tool problems/taper attach. wanted. Cutting off is one of the more difficult lathe operations. First you may be feeding too slowly, tool is not ground correctly or not exactly on center. If you are feeding too slowly the tool tends to "skip" on the work producing chatter. Tool set too low or high will leave a "pip" on the stock. For many part off operations I cut a bit in one place, then back off and move over about 1/2 or 3/4 of the cut off tool width and cut another groove. This leaves plenty of chip clearance and makes cutting easier. A slight length-wise shallow groove in the top of the tool will also help keep the chip from jamming in the cut. If you are parting brass stock try using an oil stone for just a couple of swipes as if you were dulling the edge. Cutting on brass the tool tends to be pulled into the work, hogging and making a mess of your work and in worst case your tool. John Meacham High Desert of California, Palmdale, Littlerock. ------- Date: Sun, 07 Oct 2001 11:05:45 -0400 From: Richard Parker Subject: Re: cut off tool hates me > Why am I having sooo much trouble using a cut off tool? I follow the > directions. I'm taking my time. I'm eating right. I acknowledge a > higher entity. Is there a high/low cap or limit to what size stock > you can cut off? Parting or cut-off tools are traditionally a bit of a PITA, Hank. There's many variables to consider when they don't perform properly, and experimentation is usually the best way to learn "what works with what". Rigidity and on-center (or slightly below center) application of the tool is one factor. Naturally, you wouldn't want more tool hanging out of the holder than you need. Perpendicularity to the workpiece is a must, and thickness of the tool is yet another variable. Top rake geometry (or lack thereof) is yet another - some applications prefer a chip breaker, and some like no top rake at all. Increasing/decreasing side clearance and front rake can affect performance. Spindle speed can really affect things (some materials part better at high spindles, some prefer back gear). These are a few of the things that I can think of that affect the tool's performance, and any combination of the above might be right for one job but stinko for another (excepting rigidity, tool protrusion, and perpendicularity - those are constants.) Also, cutting oil should be constantly supplied via a small brush or squeeze bottle when cutting steel or aluminum - don't let the "race" that your cutting run dry. In most materials (other than free machining plastics and such), the cross slide should be fed by hand - and the feed rate is yet another variable. Take yer time, observe the action of the tool, and apply analytical corrective action using some of these points as a guideline. Try to part your work as close to the spindle as possible (again, rigidity). It may take you a little time, but you'll do fine eventually! Best regards, Rich ------- Date: Mon, 08 Oct 2001 02:55:01 +0000 From: Jon Elson Subject: Re: cut off tool hates me HUNLEY31x~xxaol.com wrote: >Why am I having sooo much trouble using a cut off tool? I follow the >directions. I'm taking my time. I'm eating right. I acknowledge a higher >entity. Is there a high/low cap or limit to what size stock you can cut >off? Cutoff is the hardest thing to do on light lathes, and is even tricky on the big ones. Some materials will not cut well. the tool height is critically important, speed is important too. You need to keep the advance going briskly into the work. Some materials work harden if you don't keep plunging, some develop chatter. Unlike some other tasks where reducing infeed helps with the chatter, on cutoff it often helps to increase the infeed rate. Correct grinding of the tip of the cutoff tool is also part of the trick. Some have recommended puting a Vee in the top of the cutoff tool, causing the chip to fold in on itself a bit. That gives the chip clearance in the groove. Lots of cutting oil is also part of the trick, this works wonders for me. Finally, if there is any looseness or free play in the stackup of carriage, cross slide, compound and toolholder, then you will have big problems. One little-known area is the gibs on the underside of the carriage. The high infeed force can lift the back of the carriage off the ways, if there is much clearance there. This will give you fits (and broken tools). Jon ------- Date: Mon, 08 Oct 2001 12:12:33 -0500 From: Jim Irwin Subject: Re: cut off tool hates me I've been making chips out of metal for about 45 years on the same Atlas 1042. Cutoff was a real challenge for me for most of those years. Several broken tools, dug-in & ruined bars and parts. I seem to have somehow "paid my dues" and now have no troubles. Maybe some confidence goes a long way. I use the Atlas cutoff tool holder with plain, straight across ground tip. The secret seems to be to set it right on center, not below, and use a sharp tool with minimal relief angle (made with the radius of my 6in. grinding wheel). Tool is extended only as far as the radius of the part being cut off + one RCH (red cat hair ...an old machinist's measurement ;>)) and the holder extended out from the tool post as little as possible and all tightened down gorilla tight (my term). That means all sources of play reduced to good'n'tight (German machinist's nomenclature ;>)) The key then is: align the tool exactly perpindicular to centerline, lock the saddle, use good lube, start & maintain the cut aggressively, evenly, firmly. Remember that as the cut progresses, you're cutting at ever-slower FPS, so adjust speed to be on the fast side at the start. If you get digging in, check the chuck jaws and dress if necessary to be sure they are tight in the chuck body and exactly parallel (when clamped down on the work) to the lathe centerline. My cutter is now ground such that I have had no trouble parting aluminum, brass, stainless, HRS and CRS. Best regards, Jim Irwin ------- Date: Tue, 9 Oct 2001 08:49:03 EDT From: AtlasTV48x~xxaol.com Subject: Re: cut off tool hates me I agree, The hack saw works everytime for me. I made a cute holder for my die grinder that fits in my QC tool holder. A 3 inch cut off wheel does a beautiful job on anything that I've attacked with only a 1/16 kerf. It also makes a nice tool post grinder for about $89 new. I always use a rubber mat with a tight hole what fits over the tool holder and covers the ways. Remember, always practice safe grinding. Dave ------- Date: Tue, 9 Oct 2001 13:04:05 -0700 From: "Bob May" Subject: Re: cut off tool hates me I find the discussion of cutting stock off fascinating! I've owned a Unimat for many years and have done all of my work with that machine unless there was a lathe available at work (I work in electronics) to do some larger stuff. I've had the problem you have all experienced with chattering and so forth much worse than what you've experienced. Remember that the Unimat has the carriage on a pair of rods that are suspended at the ends only and the carriage surrounds the rods? That makes the whole process of doing any work an excercise in keeping those rods from singing. My process in cutting off is to take a short cut with the cutter and then moving over a half a cutter and going a bit further on that side. Then back to the first position and do some more there. You only go about .050" at a time but you get the cut done and it's a nice smooth cut when you do a final pass getting the last thou on the face of the cutoff material before the final plunge. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- From: Alan Marconett KM6VV Date: Tue Jan 15, 2002 4:25 pm Subject: Re: [sherline] Parting 2" dia. ABS plastic midroof wrote: > Hello: One of the projects I have on deck will involve parting off > some ABS plastic that's 2.0" in diameter. I'm wondering whether I'll > need to make a special cutoff tool holder and cutoff tool. From the > little I know about machining, I am thinking one should have a 0- > degree rake on the cutoff tool to prevent digging in the plastic. I > don't have my Sherline cutoff tool holder yet, but I believe it holds > the tool at a 7-degree rake. I would also think that I wouldn't be > able to get the cutoff tool at the center of the part with 1.0" of > tool sticking out of the holder. Do I need to make a special cutoff > tool and holder? Thanks. Bryan Hi Bryan, OK, I can be crude. Just cut a slight groove where you want to part it, take a hacksaw, and WITH YOUR HANDS OUTSIDE the HACKSAW FRAME, gently lower the hacksaw to the groove, and make light strokes back and forth as the spindle turns. It should be easy to cut ABS off this way. You should probably stop before the end, and finish with the spindle off. CAUTION: Please, anyone doing this, or filing, etc. BE CAREFUL! we want you to keep all your fingers! (required caution message complete). HTH Alan KM6VV ------- Date: Tue, 3 Sep 2002 20:57:51 -0700 From: "Dave Hylands" Subject: Interesting problem while parting I ran into an interesting problem while parting a piece of round brass stock. The piece was 3/4" in diameter and 4-5" long. I was using a steady rest and parting about 0.25" from the end. The steady rest was about 1.25" from the end (I had knurled about this much of the end). The very first part went very straight. The second and subsequent parts caused the brass stock to be pulled from the 3 jaw chuck (towards the tailstock). This, of course, casued the parting blade to bend and not cut straight. Retracting the parting tool, the starting slot was half of the width of the parting tool closer to the tailstock. I eventually wound up using the tailstock to prevent this from happening. Does anybody know why this would happen? Is there anything I can do about it? Or is using the tailstock the only option? If it can pull the work out of the chuck, presumably it can push it into the chuck? Any insight is appreciated. Dave Hylands Vancouver, BC, Canada http://www.davehylands.com/ ------- Date: Wed, 4 Sep 2002 07:49:34 -0500 From: "Nance, Tom" Subject: RE: Interesting problem while parting Hi Dave: You might want to check how your parting tool is ground. It should be fairly square when looking down from the top. If it has a point, it will drift to one side everytime. Tom ------- Date: Wed, 4 Sep 2002 07:54:18 -0700 From: "Marcus & Eva" Subject: Re: Interesting problem while parting Hi Dave: Here are the places I would look: 1) Make sure the parting blade is ground and set up so the cutting edge is exactly parallel to the axis of rotation. 2) Make sure the jaws of the steady are precisely in line with the cylinder you are supporting. Misalignment here will slowly crawl the part out of the chuck by working it against each successive jaw as it rotates. (To get a clear mental picture, imagine setting the steady deliberately way off and then rotating the bar in it. The chuck will start trying to act like a universal joint, and chew up the end of the bar until it can flop around.) 3) Sherline chucks won't grip with much force...their construction is pretty light, and the mechanical advantage of a Tommy bar vs a crown and pinion is low. Use the 4 jaw if you need better holding power. 4) Watch for wear of the jaws or the workpiece at the steadyrest location. Wear will act the same way as steady rest misalignment. Cheers Marcus ------- Date: Wed, 4 Sep 2002 08:01:41 -0700 From: "Marcus & Eva" Subject: Re: Interesting problem while parting Hi Tracy: Yes, this is what's commonly recommended in textbooks, but it doesn't work nearly as well on tiny machines. The rigidity of the blade is often a big problem. Sherlines don't have the poop to handle a wide, stiff blade, so often the blade will flex sideways with deeper cuts. If it snags in the side of the slot it either stalls the machine, spins the work in the chuck or snaps off the blade. These machines are actually pretty marginal for parting off...I hacksaw and face whenever I can to avoid parting on these tiny machines. Parted off faces usually look like a pig's breakfast anyway and need facing off to clean up. I'm too lazy to set up the parting tool and then flip the part for clean-up, and have to set up another tool. Cheers Marcus ------- Date: Wed, 4 Sep 2002 08:14:38 -0700 From: Wm. Dubin Subject: Re: Interesting problem while parting Dave, I have had this same problem, not just with cutting off, and not just with the Sherline, but with my 6" lathe as well. So far, the replies you've received all centered on the cut-off blade, but this is (in my estimation) not the problem, the problem is the steady rest, as this same problem happened to me while doing simple turning (using the steady). I checked with a friend in Australia, and he felt the problem is based on the steady acting as if it were a NUT, and the bar stock literally 'unscrews' from the chuck. My solution was to use the tail stock, only instead of a center (as my stock couldn't be end drilled), I put a 1/4" dia faced off steel rod in the tail stock chuck and brought it up to the work end, added grease, and went to work. I no longer use the steady rest without tail-stock support. Hope this helps. Wm. ------- Date: Wed, 4 Sep 2002 09:45:48 -0700 From: "Dave Hylands" Subject: RE: Interesting problem while parting Thanks to everyone for their input. I'll be keeping an eye on this in the future, and see if I can determine if it is in fact due to the steady rest. I first turned the brass bar (no tailstock and no steady). I was taking very light cuts (0.001 or less) because I was trying to measure the alignment of my headstock to the ways. I was able to get it within 0.0004" over 3-4" (probably not really that accurate since I doubt my skills at using the micrometer are that good yet). Once I got the headstock running well, I added the steady rest and snugged it up to the piece while it was really close to the headstock, then moved it out towards the tailstock. I used a small amount of oil on the stock where the steady rest touched it and then proceeded to knurl the end and part off pieces. The first one was really nice, and the finish was much better than I was expecting. I have some pictures, which I hope to post in a few days. The remaining ones weren't so nice. Fortunately, I added 0.010 to the cut, expecting to have to finish things off a bit nicer. The parting blade was new. I think I had used it once before to shorten the length of a threaded screw. Dave Hylands ------- Date: Wed, 4 Sep 2002 18:41:15 +0100 From: "David Simmons" Subject: Re: Interesting problem while parting I'll second that, small or big. I avoid parting tools as much as possible and just cut off the part with a hacksaw. That is after years in the trade when I worked on items far to large to even dream of using a parting tool. I prefer to make a jig for very thin parts - out of Al - that way I can face both sides. The jig is very simple - a disc with a rim around the edge and then split it about 2/3 across the Dia. That way you can still use the three jaw to hold it. Another little trick - don't try this at home kids - is to cut a vee groove a little wider then the hacksaw blade, then with the lathe spinning slowly press down evenly with the hacksaw from above - make sure the teeth are the right direction. Regards, Dave S. BTW: As a youth I was told that wearing an old tie around the shop was a great way to have an instant and handy rag. I don't think that guy liked me much:) ------- Date: Mon, 11 Nov 2002 00:40:33 -0600 From: Jon Elson Subject: Re: More about the lathe disaster kdspriggs wrote: >Here is the gruesome details about how I managed to break the >compound rest on my 10 inch Atlas. I was using a cutoff tool to cut a >3/4 inch bar. I had the lathe running at the lowest speed possible >(in back gear) and was keeping the cut well oiled. Unfortunatley I >had the compound rest extended almost all the way forward. I am sure >the tool was on the centerline as I took a lot of pains with that. I >was about 3/16 inch in to the bar when it caught and broke the the >compound rest right at the back side (or maybe you would call it the >front side anyway it was the side closest to the idiot running the >machine) of the tool post slot. WOW! Major mistake! Lucky you didn't get hurt! Anyway, the 10" Atlas compound is pretty weak to begin with, and gets noticably wobbly when entended far in either direction. The lathe manual says for heavy cuts that the compound be fully supported on the base. The wobbly condition of the compound makes it more likely that the tool will wobble and possibly dig in, too. You've got to have the stiffest support possible for cutoff tools. Jon ------- Date: Mon, 11 Nov 2002 23:27:32 EST From: AtlasTV48x~xxaol.com Subject: Lathe Disasters 
After several good scares and close calls with cut off tools, I have
reverted back to the trusty old hack saw. A cut off tool light enough
to break before the Atlas does takes more patience and time than the
hack saw but I do tend to get in a hurry.

-------

Date: Mon, 11 Nov 2002 07:17:12 -0800
From: Mark 
Subject: cutoff tools

My Dremel makes real nice toolbits from thin-kerf carbide tipped saw
blades. I roll my own for positive, zero, negative rake. A jeweler's saw
would do if you don't have a Dremel.

mark

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Date: Tue, 12 Nov 2002 05:15:16 -0800 (PST)
From: gauge-onex~xxwebtv.net
Subject: Re: Lathe Disaster

It sounds to me like the only error made here is the use of such a slow
speed - I do a large amount of parting off and have absolutely no
problems doing it... I would have parted off that piece of 3/4" steel at
about 500-600 RPM. Atlas lathes are not really rigid enough to part off
at back geared speeds.

I use a Carbide tool and a steady feed - too light causes chatter and
fine, splinter-like chips... too heavy a feed could probably break
something - I have only over-fed once... the tool dug in, stalled the
spindle and slipped the motor belt. (I was lucky I guess).

Anyway, you want to produce a fairly continuous chip. Mine usually come
out as little coils - like flat snail shells - and break themselves off
when they are about 1/4" diameter.

Make yourself a little gravity-drip oil can to take care of the cutting
oil so both hands are free to operate the feed. Lock the carriage to
the bed and tighten the compound gib screws. And of course, the tool
should be sharp, square, and perfectly on center.

Regards,
Jay Dee

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NOTE TO FILE: Also see the Sherline Lathe Quirks or Tips text file for
more parting hints in the discussion starting:
Date: Thu, 03 Apr 2003 05:13:44 -0000
From: "forbes_rl" 
Subject: Problem with steady rest slipping

A perfect illustration of how one topic completely changes focus in
the discussion to another (parting off).

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Date: Fri, 11 Apr 2003 15:07:32 -0700
From: Mark 
Subject: Question parting off Titanium

Silver soldered a broken 18 inch shank carbide pc-board drill into a hole
in a chunk of mild steel. Trimmed it down to about 40 thou thickness,
slight positive rake, squared tip for cutoff. Made a nice cut into the
side of a titanium rod, but I was amazed by the cutting tip - almost a
mm had come off the top surface, which is now rounded and somewhat
mottled. Looks like it had been ablated, not eroded by the Ti.

Is this a function of the carbide grain structure, or of my heating it to
essentially red heat for Silver soldering? Or? Any other suggestions for
grooving / cutoff of ti rod?

thanks/ mark

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Date: Fri, 11 Apr 2003 20:18:19 -0400
From: "Statman Designs, LLC" 
Subject: Re: Question parting off Titanium

All I do is titanium. Here is how I part it off, assuming a depth of cut
less than 0.250", maximum diameter for a solid bar of 0.5". I use a 1mm
full radius grooving insert. TiN coated helps if you are going to part off
50 pieces with one bit. The full radius prevents it from shattering when
it gets to the end. I also part off a lot of thick walled cylinders.

You can buy a mini grooving toolholder and insert from J&L for about $50
for the holder and $13 apiece for double sided inserts.

I can part a solid bar up to about 0.6" in diameter by snapping it off
manually after grooving to the full depth of the insert. Titanium is
fairly brittle (the 6/4 alloy) and snaps off easily enough. Then you do
a quick facing cut to clean it up.

Daniel J. Statman, Statman Designs
www.statmandesigns.com    dan.statmanx~xxrennlist.com

-------

Date: Fri, 11 Apr 2003 19:17:48 -0700
From: "Marcus & Eva" 
Subject: Re: Question parting off Titanium

HI Mark:
Carbide doesn't tolerate the stress of heating and cooling all that well.
I suspect that the corners just crumbled off the tool because of
microcracks in the carbide. I've had problems of the same sort with
brazed-on inserts ...especially homemade ones.

Clamping rather than brazing the carbide insert is the best way if you
need to preserve the physical properties of the carbide. In the case of a
round stub from a broken PCB drill, a simple setscrew is adequate.

Cheers
Marcus

-------

Date: Wed, 16 Apr 2003 07:13:50 -0000
From: "sikn1gh7" 
Subject: Re: parting off brass with a cut-off tool

Advice from my shop teacher at the Univ. of Washington --
Rules of thumb for parting:

* As slow as you can go. On our 14x40" lathes, we usually spin the part at
no faster than 200 rpm, even aluminum. We have the luxury of power feed
and we always use it, typically we feed at about 0.002" per turn but it
depends on the material. On the Sherline, I understand such slow speed can
be a problem. One thing I would love to see is a hack to put an extra
planetary gearbox (such as a power drill gearbox) into the headstock.

* Lots and lots of lube. Even for aluminum and brass which can be machined
   dry.

* Make sure your setup is *VERY* rigid. This means:
- Lock the carriage, if applicable (not on the Sherline).
- Never part more than part diameter away from chuck. Deflection will
   result in a loose setup.
- Never part diameter bigger than the height of the blade - you'll get
   deflection and chatter.
- Never, EVER part between centers.

Also: Check to make sure that the blade is running true. Remember, the
tool post can move, so before parting make sure the side of the blade is
parallel to your X axis.

That said - our most common technique for parting things off bar stock?
Horizontal bandsaw, then putting it back onto the 3 Jaw to face the other
end. Much, much faster - the bandsaw blade costs about as much as a
parting tool but it's less likely to break. :-)

Hope this helps!
Terence

-------

Date: Wed, 21 Jan 2004 14:07:42 -0000
From: "mmurray701" 
Subject: Advice on parting? [using a mill -- posted to taigtools group]

I've been trying to make a batch of round parts using my CNC mill as a
lathe. I made a toolpost and everything is working surprisingly well so
far. Facing and regular outside cuts are all working amazingly smooth.

But I cant seem to be able to part things off without chatter. I recently
bought one of those 1/16th wide parting tools on e-bay and this helped but
i'm still getting alot of vibration. I assumed it was because of my
homemade tool post, but all the vibration seems to be comming from the
headstock.

Any advice? Everything is tight. I've tried different speeds and feeds but
it doesn't seem to help. Is this all I should expect out of a Taig? How
well does the lathe part things off? I'm working with 1" aluminum by the
way. Thanks!

Mark

-------

Date: Wed, 21 Jan 2004 14:55:36 +0000
From: Steve Blackmore 
Subject: Re: Advice on parting?

Probably the toolpost rather than the headstock, it needs to be very
rigid. The more so the better. If you can try inverting the tool and
parting from the back (opposite side on the mill). Also keep the feed on,
it can be a bit of a juggling act, parting tools like a steady infeed and
probably at a higher rate than you would expect.

Steve Blackmore

-------

Date: Wed, 21 Jan 2004 15:27:55 -0000
From: "Ed Chesnut" 
Subject: Re: Advice on parting?

Cutting edge height on center?

-------

Date: Wed, 21 Jan 2004 16:25:08 +0000
From: Tony Jeffree 
Subject: Re: Advice on parting?

I suspect that this is a simple problem of stiffness - the mill's Z-axis
is almost certainly not as stiff as the lathe bed (consider - with the
lathe, you would be parting off near the headstock, therefore there is
only 3" or so of bed to flex; with your "mill that thinks it is a lathe"
setup, there is a considerable length of Z-axis to flex). Parting off
generally puts heavy loads on a lathe - I suspect you are probably just
working outside what the setup is capable of.

I have occasionally wondered whether the Z-axis column (which is basically
a piece of heavy gauge square section tube) would benefit from a concrete
filling to stiffen it, rather like the lathe bed; might improve matters.
Apart from that, if checking centre heights, using lubes (Kerosine/WD40)
etc. makes no difference, I would go for the old hacksaw-it-off-and-then-
finish-the-raggy-end-in-the-lathe technique (which I often use anyway if I
can't be bothered to fit the cutoff tool to the cross-slide).

Regards,
Tony

-------

Date: Wed, 21 Jan 2004 16:40:54 -0000
From: "mmurray701" 
Subject: Re: Advice on parting?

Thanks for the replies guys. The center height is good, Tried both water
based coolant and kerosene. I'm thinking I'm just outside my limits as
well.

The tool post probably doesn't help things. Its 1" square steel and about
2.5" high. But it really doesn't seem like the vibration is here. You can
put your hand on it and it seems solid, no vibration at all. On the other
hand, you lay your hand on the headstock and you can definitely feel it
vibrating. The column seems solid as well.

It still will part the thing off, just squeals really loud. Any reason why
I can't just let it chatter its way through? Is this going to damage
anything (other than my ears)?

I guess I could chop it off with the bandsaw after removal, but this would
slow things down considerably.

-------

Date: Wed, 21 Jan 2004 08:24:29 -1000 (HST)
From: Tom Benedict 
Subject: Re: Advice on parting?

I've been doing mill-as-lathe parts recently, too, and found an answer
for this.

Because of some constraints on the shape of the part, I've been using a
diamond point tool. It'd look like a threading tool except it's got a 15
degree included angle instead of a 60 degree included angle. The parts
I'm working on have features on the order of 0.002" wide, so there's
almost no tip radius on the tool.

When it came to parting I figured I'd plunge the tool into the work. At
that point the work is pretty thin, so no big deal, right? WRONG! I
destroyed a bunch of parts that way.

I was still looking for an answer when I had to make some parts using a
similar setup. Only this time the parts wound up being almost a quarter
inch in diameter at the point they needed parting. Plunging snapped a
couple of those tools (they're fragile as all get-out), so I looked for
another way.

If you don't mind a slightly wide parting slot, you can treat the parting
operation as a normal lathe turning operation. Plunge in a couple of
thou, take a light pass across your wide parting line. Go back, plunge in
a couple more thou, take a light cut. Eventually you whittle the thing
away to practically nothing and the part falls off. You're only ever
cutting with the very tip of the tool, so the cutting forces are minimal
at best.

On a manual lathe this would be tedious beyond tedious. In CNC it's just
more toolpath. No big deal. And the results aren't that bad. It parts off
the part just fine. The only drawback is you eat more material doing it
this way.

Tom

-------

Date: Wed, 21 Jan 2004 21:48:02 -0000
From: "mmurray701" 
Subject: Re: Advice on parting?

Tom, thanks for the tip. The point of my new parting tool is basically
square so I'll have to re-grind it but that isn't much of a problem.
I'm sure this will work.

I actually used to use this method when trying to part things on my
father's Unimat (a nightmare!), just didn't think about doing it here.

Thanks!
Mark

-------

Date: Fri, 23 Jan 2004 20:48:46 +0000
From: Clive Foster 
Subject: Parting off and back Tool Posts

Folks: Back tool posts are an effective and widely used panacea for
chatter and other parting off problems on small lathes but the magic is
more in the action of the feed screw than in the position of the tool.

With a conventional front tool post the screw is pushing the tool into
the work. Being a slender column it is obviously weak in bending and,
given half a chance, will try to run away from the load by buckling.
Obviously it can't collapse completely but it will bow and any change
in the pressure on the tool point will alter the amount of bow needed
to support the load so, unless we can keep an absolutely constant
pressure the screw will effectively be trying to" vibrate" in a transverse
mode. Such vibration will change the feed slightly which in turn will
change the load re-enforcing the effect (us techies call this positive
feed back) so it doesn't take long before you have a nice chatter going.

If you have a back tool post the cutting forces are put on by pulling
the feed screw so it is in tension. Even the thinnest piece of steel
wire takes a fair load to stretch it (tried tuning a piano recently?)
so basically even the smallest of screws wont allow the feed to change
with load variations effectively breaking the positive feedback. As
long as you have enough feed load to keep the feed nut and screw in
positive contact the tool will advance nicely through the work.

I think it would be well worth seeing if the feed screw can be
re-arranged to be held at the back, working in tension. This ought to
improve cutting capability and finish with normal tools as well as
helping the part-off process. A normal fixed bearing at the back
(angular contact ball race??) with a "Alinbal" type bearing (like a
ball rod end) at the dial end seems a good way to go.

In my view the major advantage of the back tool post is that its pretty
much a permanent fixture making it worth taking plenty of time to get
the tool alignment absolutely right so it cuts straight across without
arguing with the side of the cut.

George H Thomas describes some experiments with different parting tool
tip shapes in his book "The Model Engineers Workshop Manual". The shapes
look fiddly to produce but I can vouch his the demos were convincing.

HTH.
Clive

-------

Date: Thu, 15 Apr 2004 18:55:02 -0700
From: Don Rogers 
Subject: Re: cutoff tools

I'd like to make a couple remarks about the cutoff tools.  Setup on these
are very critical.  There is no relief along the tool. That means that the
tool has to be exactly perpendicular to the work axis. I use a 1" sq tool
bit as a square setting up cutoff blade. No amount of lubrication or tip
grinding will prevent this need.

Now, for the tip of the tool. When grinding the tool, don't grind the top
of the tool. Any grinding there will cause a wedged shape tool, with the
cutting edge at the narrow point and a scrapping edge along the sides. The
face of the tool needs to be cut at an exact 90 degrees to the top of the
tool. 89 Degrees will cause the tool to try to wander when pushed into the
work.

The cutting edge of the tool needs to be set exactly on the axis of the
work. Too high, and you run into a area of the tool where it won't cut the
last bit and jams. If it is low, then you leave a small rod in the center
and the closer to the center the cut gets, the more the cutting angles go
to hell.

Keep the blade as close to the support as possible.  Two inches of tool
projecting past the holder is not needed for a 1/2" cut. It lends to a
bent or broken blade, or one that overheats and looses hardness.

Last, parting is not a process that you can ease into, it takes brute
force. The variable speed spindle is nice in that you can increase speed
as you get nearer to the center to keep up the ft/min cutting speed to the
best results. Just remember that 1/4" rod that is sticking through the
head stock by a couple feet and was wobbling around a bit will wobble a
lot and may bend as the speed increases. If you are feeding a long rod
into the lathe, support is necessary, and not just under the rod, but
enclosing it.

Don

-------

Date: Thu, 18 Nov 2004 09:05:54 -0800
From: Don Rogers 
Subject: Re: parting off [taigtools group]

>Does anyone have suggestions as to a better setup or the best way to
>grind and sharpen the cutting tool?

On Sharpening the tool, only sharpen the end of the tool, never touch the
top or sides. Keep the cutting tip exactly square with the length of the
tool.

Absolute alignment is required for success with a parting tool. I keep a
1/2" tool bit at had to use as a mini square when aligning the tool to the
work. If you are off by just a tenth of a degree, the tool will drag on
one side, bending the tool and it just goes down hill from there. The the
tool wants to be exactly on center. Too low and you lose your cutting
angle; too high and you don't have relief and the body of the tool hits
the work.

The quick change post on the Taig has it's problem in that there is a lot
of leverage from the tool to the center post, and it is quite easy to turn
the post when applying tool pressure like needed for parting, or even just
tightening the QC clamp. The 10-32 screw just doesn't have enough pull to
lock the post and it's riser to the cross slide. I think that doing a
relief cut on both sides of the raiser would help this.  Make sure the
screw will fully tighten without bottoming in the T slot, but be fully
engaged in the nut. This takes some washer work on the top to get it just
right. You need all the holding power you can get.

One other idea comes to mind as I am writing this. A top plate for the
cross slide, from 3/8" cold rolled steel, four corner mounting, maybe an
additional two in the center, drill pattern of 5/6" NF holes and then
replace the center screw with a 5/16 stud and nut on top. You will have to
bore out the top of the blue center post to accommodate the 5/16 stud, but
there is plenty of relief on the bottom part of the center. A slight
relief on the bottom of the black body would be in order using this
approach. Really tightening down on the stud may distort the bottom of the
black body enough to loose it's grip on the plate. You would also want to
countersink the threaded holes in the CRS so you don't have a thread pull
up and cause you to lose the fit.

Don

-------

Date: Thu, 18 Nov 2004 11:10:10 -0600
From: "Bad Brad" 
Subject: RE: parting off

>I've been having trouble lately when using the parting tool.  I'm
>using the TS Engineering setup with a 1/2 blade.  The problem is that
>I am getting loud screeching sounds and chattering.

Make sure your tool hieght is correct, sounds like your tool is to high.
Run the slowest spindle speed you can and use a ton of lubricant. Also
there should be proper clearance. Don't stone the top edge of the cutting
point by hand because you will round the corners and the bit will wedge
into the cut as a result.

I sharpen my cutoff tools at a 30 deg. angle from flat just on the
outboard end only. Make sure the cutting edge is square to the edge of
the tool too.

Happy cutting!
Bad Brad        Rabid Weasel Racing Team

-------

Date: Mon, 23 May 2005 01:23:43 -0000
From: "David" 
Subject: Parting Chatter [taigtools]

I just could not part anything without severe chatter, so guess what
solved it ? A hand crank on the chuck spindle. Just turn it about 2
rpm. Better than sawing it and re-chucking and facing.

-------

Date: Tue, 14 Mar 2006 17:27:26 -0800
From: Steven Harris <79ramchargerx~xxwavecable.com>
Subject: Re: Cut Off Attachmnent [atlas_craftsman]

Michael Spivey wrote:
> Has anyone seen or have they built a cut off attachment for the back
side of the carriage on the 12 inch craftsman lathe? If so, would they
be willing to share the drawings or pictures as I would love to build
one without reinventing the wheel. <

Try this
http://www.statecollegecentral.com/metallathe/A-11.html

Steve

-------

Cheap parting /cut off tools [atlas_craftsman]
Posted by: "Ted Lotz" mototedx~xxyahoo.com
Date: Sat Nov 18, 2006 4:53 pm ((PST))

Hi there, I've had my "new" lathe for about 6 months now (1941 12"x 36"
from the original owner, he was 82 years old and bless his heart he was
crying when I loaded it up and left his driveway). Thanks for all the
useful inforamtion in this group. Haven't seen this tip before so I
thought I'd run it across you guys. Was playing around last night in the
shop and took a 7 1/2" carbide tipped circular saw blade that had a few
teeth missing to the old bandsaw, cut it into 1/2" wide strips to fit my
parting tool holder and presto, free parting tools that cut fantastic.
They seem to have a small angle on the carbide tip, but hey, one trashed
40 tooth blade will make at least 20 parting tools.

Ted,
Proud owner of a classic American made lathe.

-------

Re: Cheap parting /cut off tools
Posted by: "Ted Lotz" mototedx~xxyahoo.com
Date: Sun Nov 19, 2006 4:53 am ((PST))

> Hi Ted, I can sympathize with the former owner! It's kind of like
> closing the book on one's life when it comes time to dispose of your
> tools & toys! So far as the cut off is concerned; what a great idea.
> Now, how did you cut the blade into strips? I assume, you used your
> bandsaw. How did the blade fare? Cheers, Jay Greer

Seems that circular saw blades are made of a softer metal than it would
appear. I've just got the common 4"x6" bandsaw and it sliced up nicely,
just be sure and miss the carbide tip!

Good luck,
Ted Lotz

-------

Cut-off tool for 6" Atlas [atlas_craftsman]
Posted by: "allan.ostling" aostlingx~xxgmail.com
Date: Tue Oct 9, 2007 9:49 am ((PDT))

I've recently acquired a 6" Mk.2. The carriage is now de-shimmed, the
bed is leveled, and I'm ready to make some first chips. But I'm
stymied by the first thing I plan to do.

I have a 12" length of 4" dia solid Delrin. I want to cut off 0.5"
lengths, discs on which I will do subsequent turning and facing. I was
thinking of using a cut-off tool, making a groove perhaps an inch deep
on which I could then use a hand saw to complete the through cut.

I can just manage to grasp the end of the 4" diameter in my 3-jaw,
with the jaws reversed. The other end is supported on a live center.

I can't use a cut-off tool in a holder mounted in the tool post -- the
cross-slide travel is not great enough to initiate a cut at a 4"
diameter. I'm wondering if I can achieve my needed cut-off capacity by
using the Cut-Off Tool Block, accessory #10106. This is substituted
for the conventional tool post, and provides greater rigidity. I don't
have this, so I can't try it to see.

--------

Re: Cut-off tool for 6" Atlas
Posted by: "LouD31M066x~xxaol.com"
Date: Tue Oct 9, 2007 10:00 am ((PDT))

Since you are not going for extreme accuracy a temporary tool fabricated
from whatever comes to hand will probably get you from where you are to
where you want to be. Don't be afraid to think outside the box and it
does not have to look elegant or last longer than the last cut....although
better to build better than you need to in case you might want to make
more. I have a little experience with turning Corian that worked out just
fine. Delrin may be subject to digging in. I  would advise to get a piece
to practice on to get used to how it goes.

Louis

-------

Re: Cut-off tool for 6" Atlas
Posted by: "Paul DeLisle" ferretpdx~xxgmail.com
Date: Tue Oct 9, 2007 8:13 pm ((PDT))

As some else said, think outside the box.

Using the whole piece, cut/face the front (most complex) side of the piece
you want. Then take a fine Sharpie marker (or a pen/pencil), and mark
about 0.6" back from the edge, at several places around the piece.

Spin it up on the lathe, and connect the dots with the pen. Then, take
a hacksaw, and *carefully* start your cut.once you have a clean groove,
start sawing away.

If you're lucky-enough for the piece you want to be flat-backed, sand it
smooth on a Surface Plate, or a tabletop with sandpaper. Otherwise, chuck
the remainder up, and start cutting carefully.

Repeat until you have enough pieces, or until you're out of material!
Hope this helps!

Paul DeLisle

-------

Re: Cut-off tool for 6" Atlas
Posted by: "jmartin957x~xxaol.com"
Date: Wed Oct 10, 2007 7:58 am ((PDT))

You've got a couple of problems, because the lathe really isn't big enough
to do what you want. But people with small lathes often find ways to stuff
work in them that the lathe wasn't designed to handle. So, there may be
ways to do what you want.

The lathe will not swing a 4" piece over the cross slide. Close, but not
quite.

But - you can remove the cast piece which covers the cross slide ways, and
you'll have your 4". The cast piece also holds the cross slide feedscrew
nut, so you'll have to put some washers or something in its place.

Or - you can work off to the left of the cross slide. There are a number
of ways to do that.

A right offset cutoff toolholder, held in your lantern toolpost, may allow
you enough clearance to get the 1/2" thick pieces.

A straight cutoff toolholder might work if you turn the compound slide
parallel to the lathe axis (or even aimed back toward you a bit) and feed
it out to the left of the carriage. Be careful, though, as the compound
slide can break.

A boring bar would probably give you the clearance and feed you need.
You'd have to grind up a cutoff bit for it.

For Delrin, you could always try a handheld cutoff tool, such as a wood
turner's parting tool. For a tool rest, try a boring bar.

Lots of ways to skin a cat.

The tool block would probably work, although you might have to remove the
way cover as above.

Supporting the piece with the tailstock is a must in this case. You'll be
finishing the cuts by hand anyway.

John Martin

-------

Re: Cut-off tool for 6" Atlas
Posted by: "allan.ostling" aostlingx~xxgmail.com
Date: Wed Oct 10, 2007 5:05 pm ((PDT))

John, I can tell you have swung a 4" diameter. You are right, removing
the carriage guard cover is all that is needed to make this possible.

I took your advice, turned the compound parallel to the bed, and saw
immediately that this does the trick. I can use a cut-off tool without
interference. This was a forehead slapper, when I saw what I'd overlooked.

Allan

-------

NOTE TO FILE: Cutting off yellow brass is a thread in atlas_craftsman
starting Apr 5, 2008 and that conversation may be found here on my
site in the file called Turning Brass. [Yes that thread could have been
put into this file but the conversation includes some general turning
information applicable to turning brass, as well as comments on rigidity
of the lathe involved.]

-------

Does anybody have a real 3-jaw? [Subject actually parting off] [sherline]
Posted by: "Jim Ash" ashcanx~xxearthlink.net
Date: Mon Sep 8, 2008 6:29 am ((PDT))

Has somebody got a recommendation on a 3-jaw chuck manufactured by someone
other than Sherline that actually holds on a Sherline lathe when you want
it to?

I was parting off a whack of aluminum yesterday with a cutoff tool,
sticking maybe 2" out of the standard 3.1" Sherline chuck, just over an
inch in diameter. All good machinists know (#1) you don't use a cut-off
tool while turning between centers, so it was unsupported on that end,
and (#2) when a cutoff tool chatters, you need to lean into it a little
more, not back off, which I did.

With a cut this deep, I was using lots of oil and keeping my rpms down.
The cutoff tool was sharp, set at the right height, and square with the
chuck face. I don't have any complaints with cutoff tools like some; if
you repect the tool and what it's for (and what it ain't), it's a fine
tool for a specific need.

Twice, the cutoff tool bit and pulled the work off-center in the chuck.
The piece was obviously marred where the jaws were gripping it, but
that's not a problem for this piece. Yeah, I know the Sherline 3-jaw is
notoriously weak, but I was gambling there was a sweet spot between the
force required to get the cutoff tool to work and the force it took to
dislodge the work from the chuck. I lost that gamble. I was being lazy
because I didn't want to take the time to dial-in the work on the 4-jaw,
which is what I ended up doing anyhow.

Either I get a chuck that works, or I'll just make a personal rule that
thou shalt not part with other than the 4-jaw.

Jim Ash

-------

Re: Does anybody have a real 3-jaw?
Posted by: "DA Dossin" danatlx~xxyahoo.com
Date: Mon Sep 8, 2008 6:49 am ((PDT))

That rule about not using a tail stock center while using the cut off
is flexible. There is a difference between keeping it tight against the
work and merely providing support for the work in the center drill hole.

I have, in the past, used the live center loosely in the hole. When the
cut off blade is extended and the remaining metal is small in diameter,
I am usually down to a crawl when it comes to RPM.

I guess you could use a steady rest (PN 1074).

Every now and then, you will see someone offering, on EBay, steady rest
blades with small bearings on the ends. I have a set of those and they
seem to work very well.

Dan

-------

Re: Does anybody have a real 3-jaw?
Posted by: "Jim Ash" ashcanx~xxearthlink.net
Date: Mon Sep 8, 2008 7:33 am ((PDT))

Given the initial diameter of the part, I've used the cutoff tool fully
snug to do the bulk of the cut in the past, then backed the center away
when it's getting down there for the final drop. Unfortunately, this time
the finished part was on the end of the rod and didn't have a hole in it.
The outside diameter of the part was unfinished, so the steady rest was
out (although I guess I could have turned it first), and the diameter of
the stock precluded me from sliding it into the spindle and getting the
part closer to the chuck.

Jim

-------

Re: Does anybody have a real 3-jaw?
Posted by: "n2562001" jlkiefferx~xxcharter.net
Date: Mon Sep 8, 2008 7:36 am ((PDT))

Jim: Assuming I understand your setup, I know of NO three jaw chuck that
would hold under the same conditions.

First you were holding aluminum that is soft and hard to hold rigid
because the surface will easily deform allowing it to loosen in the jaws.
Next you are trying to hold this piece of 1.000" diameter material with
ONLY 3/8" OF JAW LENGTH. If you try to part or machine stock held in ANY
three jaw chuck extended in front of the jaws further than the gripping
length of the jaws themselves, you put yourself at a disadvantage.
Anything greater than this will require support such as a center or steady
rest.

Also you should not always believe everything that hear about procedures
as also suggested by Dan. What applies to larger machines seldom applies
to small machines the size of a Sherline. In this case the stock could
have been supported by centers or a steady rest without issues.

In regard to my first statement, your setup would be similar to the
following setup in my 13x40 lathe. In scale it would be similar to
2.000" stock held by .750" of jaw and extended 4.000" in front of the
jaws. Even in this 6" $3000.00 three jaw chuck, disaster would be almost
immediate without support.

Jerry Kieffer

-------

Re: Does anybody have a real 3-jaw?
Posted by: "DA Dossin" danatlx~xxyahoo.com
Date: Mon Sep 8, 2008 8:18 am ((PDT))

Oh no!  Jim has admitted to breaking a rule LOL.

And while we are in a confessional mood, I too have used the center tight
against the work until, I felt uncomfortable with the small remaining
diameter. Then I will back the center out a bit or support the work with
my hand but always, when down to that last 'little bitty nub', the RPMs
are at a crawl. I hate to chase parts across the room or worse, duck to
get out of the way. Plus, if you pop a part out of the lathe at low RPM
there will be less damage than if you pop it out at high RPM. 

Rules, by definition, are never meant to be broken unless there is no
other way to accomplish the task and no one is watching and understanding
the possibilities and results of your actions.

Dan

-------

Re: Does anybody have a real 3-jaw?
Posted by: "DA Dossin" danatlx~xxyahoo.com
Date: Mon Sep 8, 2008 9:02 am ((PDT))

Jim, unless the part needs to be long... bite the bullet and make the
stock shorter. We have all done that and later found a use for that
little bitty part left over.

Two bins... one for uncut stock. One for parts or 'yet to be discovered
usable items.

But Jim, NEVER believe anything I say unless JerryG "almost" agrees with
me. 

Dan

-------

Need help in Parting [sherline]
Posted by: "luna3992" arvindkx~xxoptushome.com.au
Date: Sat Feb 28, 2009 10:55 pm ((PST))

Hi all
I am venturing back into this forum after a gap of one long year. I had
earlier requested help on how to part a job properly in the chuck of the
Sherline lathe. That was the time when a great debate and trials about
the holding effectiveness of the chuck were posted. There was even a post
quoting Joe Martin on the quality of Sherline chucks.

Frankly, I was daunted by all the "guru" posts which deal with esoteric
aspects of how there is no such things as a perfect hole!! I felt that a
newbie like me did not get much help. The only help I got was from
DA Dossin who was kind enough to email offline. His advice was very good,
but did not solve my problem.

This post is getting too long so I will get to the point.

I chuck a piece say 1 inch dia., set the parting tool (at the front)
as correctly at centre height as I can, use a small engineer square to
check that the parting tool blade is at right angles to the longitudinal
axis, and use cutting oil. The piece is properly secured in the chuck,
using tommy bars to tighten.

The result is that when starting to part the workpiece, it is slowly being
pulled out of the chuck (towards the tailstock). The blade of the parting
tool (it is sharp, being brand new) is being slowly deflected towards the
tailstock. If I were to continue, the blade will snap of course. This
happens even when I try with the power off, turning the chuck by hand.
That was when I cried out for help on this forum.

I have repeated the test a number of times with same results. Oh yes, the
saddle is locked. When I see the parting blade deflect, I withdraw the
tool and the blade makes a twang as it draws clear of the workpiece.

Since I did not get much help, I went to the extent of buying a brand
new chuck. Guess what? Identical results!!

IT IS OBVIOUS TO ME THAT ONE OR MORE OF MY SETTINGS IS WRONG. WHAT IS
CAUSING THIS MASSIVE LONGITUDINAL FORCE TOWARDS THE TAILSTOCK ?

I finally finished parting the piece by supporting it by a live centre in
the tailsock. IT WAS LIKE CUTTING THRU" BUTTER!

Please HELP
Arvind

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Re: Need help in Parting
Posted by: "Andy M" trumpy81x~xxoptusnet.com.au
Date: Sat Feb 28, 2009 11:55 pm ((PST))

GDay All, luna3992,
I had the exact same problem the first time I used the standard sherline
parting tool that came with my lathe package.

If you set up the parting tool so that it cuts in front of the workpiece
(the parting tool is between you and the work piece), the angle of the
cutting edge will tend to push the material towards the tail stock as
you described.

The way I stop the same thing happening, is to regrind the blade with
little, or no angle at all, so that when you look at the top edge of the
blade it is square at the cutting end but still has the 7 or so degree
angle when you look at the side of the blade. (Hope that makes sense.)

I don't know if this method is correct or not but it works for me. I
also use a fairly slow spindle speed/feed rate when parting off with
this tool.

Regards
Andy M

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Re: Need help in Parting
Posted by: "a3sigma" dcclark111x~xxcomcast.net
Date: Sun Mar 1, 2009 3:40 am ((PST))

> The bar was maybe 2 in. within the chuck, or at least as much as the
> jaws will take, with possibly an inch sticking out and the attempt
> was to part off about 3/8 of an inch. Arvind

Hi Arvind,
Sorry for all your troubles and that you haven't gotten a resolution
here. A couple of additional thoughts:

RE the above: You began by describing a 1" diameter piece. But that
won't fit into the chuck past the fixed plate. Am I misunderstanding
something? I don't think you've said what the material is.

"Brand new" is not necessarily sharp or properly ground. Looking at
the tool from the top in position to cut; is the cutting end parallel
to the work or at a slight angle. Do you have a grinding wheel? If
not, you really must get one. Have you tried grinding the end flat,
or at the opposite angle which would tend to steer the tool in the
other direction?

I'm not really understanding your setting the tool perpendicular to
the axis with a square. The way to do this is to make the parting
tool parallel to the cut face of the work by holding it against the
face when tightening the tool holder on the cross slide.

Just read your post of a moment ago. A cut off tool may be ground
perfectly square on the end. The standard .040" thick Sherline tool
will work fine in most materials like this. A slight angle may cut
easier in harder materials. To test the hypothesis that the tip angle
is responsible for your difficulties, grind a distinct angle the other
way and see what happens.

A shot in the dark: are you certain that the cross slide is running
perpendicular to the bed? Are the gibs properly tight?

Do you mind telling us where you're located? Perhaps someone can come
and take a look.

Stick with us. There has to be a solution.

DC
David Clark in Southern Maryland, USA

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Re: Need help in Parting
Posted by: "Keith Green" ksggx~xxtelus.net
Date: Sun Mar 1, 2009 5:51 am ((PST))

One of 2 things then.
The part is coming out of the chuck because of either not enough holding
force applied by the jaws or too much tool pressure on the part (overcomes
the holding force of the jaws). The part begins to wobble (even a small
amount is bad) and will 'walk' out of the chuck. When you had the
tailstock in, it prevented both. I have read on this forum before where
guys part off most of the way down with the tailcenter in and remove it
for the last bit. Maybe this is what you'll have to do...

The fact that the material parted easily with the tailcenter in there says
to me that your tool was probably not dull or set up incorrectly. Grinding
an angle on the front of the tool, weeelll. Hmmm.

I think I would go with no angle at first. My experience with nose angle
is that most often it's on there for production-type work where you don't
want an added operation to get rid of a burr or little nub which a tool
with no angle will often leave. If the angle is ground on so the longest
point is nearer the chuck, the burr/nub will end up on the parted-off
piece and vice-versa.

I don't know about on these small machines, but on the full-size ones I
generally use, the quickest way to set the tool up is to wind it up to
the chuck and align it parallel with the chuck face. To set it on center,
pinch something flat like a ruler (lightly) between workpiece and tool
tip. Move the tool up or down until the (ruler) is perpendicular to the
lathe bed. This is all done by eye. On such a small machine you might
have to come up with other tricks; at least until your eye gets trained.

Good luck,
Keith

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Re: Need help in Parting
Posted by: "n2562001" jlkiefferx~xxcharter.net
Date: Sun Mar 1, 2009 8:03 am ((PST))

Arvind: Your settings are not wrong.

It is not practical to part off 1" diameter stock in a Sherline lathe
without tailstock support. At 1" diameter, the Stock is only held by 3/8"
of chuck jaw length. The force and torque required for parting in this
diameter cause the stock to work its way loose in the jaws and be forced
out of the chuck toward the tailstock. It will not make any difference
if it is a four jaw or three jaw chuck or what brand. You may get lucky
from time to time but most of the time you will experience what you
experienced. As you found out, tailstock support for parting in a Sherline
lathe is not an issue. This is all part of the learning curve that is only
learned by making chips.

Some additional notes for future projects.

Your stock must be machinable. For example, the chances of parting off
Home Depot steel that is full of slag is about zero to none without
tool damage.

I would suggest that you limit parting blade width to a max. of .040"
of the Sherline parting tool. The Sherline angle blade parting tool is
designed for parting in the FRONT ONLY. The horizontal blade tool is
designed for the REAR ONLY. In use you will find the rear mounted tool
to be the most efficient. Of course the tools need to be centered
to the spindle and sharp.

When parting the use of cutting fluid is a must.

Speeds should be adjusted to match the cutting loads as outlined in the
Sherline Parting tool instructions.

Jerry Kieffer

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Re: Need help in Parting
Posted by: "a3sigma" dcclark111x~xxcomcast.net
Date: Sun Mar 1, 2009 11:56 am ((PST))

> Your settings are not wrong. It is not practical to part off 1"
> diameter stock in a Sherline lathe without tailstock support.

I'll be as blunt as you always are Jerry (it's a good thing to be):

It's Deja Vu all over again. We seem to have come right back to where
we were a year ago in the discussion of holding power of Sherline chucks.
Which discussion prompted my tests and paper.
see: http://tech.groups.yahoo.com/group/sherline/files/D.C.Clark/

And I'll say again; I routinely hold work of this size and even larger
during every sort of machining operation including milling. From the
poll conducted here at that time, about 25% of members report having
problems with the holding ability of their chucks. And 75% do not.

It distresses me to have to say to Arvind and the rest of that 25%
that you're just out of luck. My tests conclusively showed an enormous
discrepancy between Sherline chucks. Some of the measurements I made
indicated a holding ability that was just ridiculously low -- so low as
to be almost useless. If I owned a chuck that performed so badly, I'd
send it back, and keep sending them back until I got one that worked.
If anyone wishes to do this, feel free to send along a copy of my report.

Better still, repeat some of the tests I performed and see for yourself.

DC

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Re: Need help in Parting
Posted by: "bushman31x~xxaol.com" bushman31x~xxaol.com
Date: Sun Mar 1, 2009 8:03 am ((PST))

Another cause could be initial feed rate. If you try to bring the parting
tool into the piece at too high of a feed rate, this could cause the tool
to deflect before it even starts to cut. I always bring it in slowly, and
when  the tool has a good bite, then I increase my feed rate as needed.

A couple of other reminders. Have the parting tool as close to the chuck
as possible (less deflection of the work piece), and your spindle RPM's
should be only half of the  normal turning speed.

Hopefully this helps some.

Ron  Wilkinson
Great Salt Lake Ship Modeling and Research Society
Nautical Research Guild   Society For Nautical Research

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Re: Need help in Parting
Posted by: "Alan Haisley" alanhyx~xxroadrunner.com
Date: Sun Mar 1, 2009 10:32 am ((PST))

Arvind: The front mounted cut-off tool must always be extended a fixed
amount, regardless of the material size being cut. Because it mounts
on an angle and the cutting tip needs to be on center to the part,
there is only one extension that will allow this.

Having read the comments here, I wonder if the blade is mismounted in the
holder with the bottom edge cocked in or out. If the blade vertical
centerline is not exactly perpendicular I would expect Bad Things to
happen.

Also, I suggest that the blade be ground square across the front for
now, rather than angled either toward or away from the chuck. As this
problem is worked out you might try a small bit of angle. My own angles
slightly so that the chuck side is just a bit longer than the other side
- but this is an accident since my preference would be to angle it just
slightly the other way.

I line up my cut off holder by using a small square against the slide
edge and lining the holder up on the blade. To my mind, this is better
on a Sherline since if the headstock is slightly turned from square
aligning on either the part or the chuck will actually set the tool on
an angle with respect to its direction of travel during a cut.

Alan

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Re: Need help in Parting
Posted by: "Alan Haisley" alanhyx~xxroadrunner.com
Date: Tue Mar 3, 2009 1:24 pm ((PST))

Arvind, I'm wondering now if perhaps you are taking just too big a depth
of cut. I'm suspicious of your comment that you are trying to turn the
piece by hand. Cutting off a piece of about .8" by hand would take
virtually forever with the Sherline since during cutoff the depth of
cut removes a ribbon somewhat thinner than aluminum foil on each turn.

I think you may have more luck if you back up, run the lathe at about
300-400 RPM, and feed just at a rate that lets you peel off a thin
foil like chip. If you overfeed the tool will indeed bite into your
work and most likely lift it in the chuck. Keep the feed firm but try
not to overpower it.

After my last message, I went to my lathe and put a 2" [50.8mm] piece of
1/2" [12.7mm] 12L14 in to try. The piece was held deeply in my 3 jaw
chuck and turned at about 300 RPM. I was able to easily cut .2" [5.08mm]
off the end, which meant that my cut off tool was about 1.5" [38.1mm]
away from the chuck.

Granted that your piece is less firmly held, you are still cutting much
nearer the chuck and at other times I have done so with larger pieces at
about the distance your pictures imply you are cutting. It seems quite
possible that you are simply overfeeding and jamming the tool in the
part, or at least causing enough upward force by your depth of cut that
the chuck simply can't hold it.

It's too bad that when Sherline put their lathe demos together that they
didn't include a couple using the cut off tool.

Alan

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Deburring OD of parted aluminum stock [taigtools]
Posted by: "John" johnsaundersx~xxpetruspartners.com
Date: Mon Mar 9, 2009 7:47 am ((PDT))

Is there a tip, trick or tool to debur the outside diameter of a piece
of aluminum stock?  After I part it off, sometimes there are burs. A
deburring tool works greated on the ID and I would like to debur/put a
very small chamfer on the OD, which is sometimes up to 2" or 3". Thoughts?

Thanks.
John
www.nyccnc.com

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Re: Deburring OD of parted aluminum stock
Posted by: "Jeff Demand" jdemandx~xxgmavt.net
Date: Mon Mar 9, 2009 8:32 am ((PDT))

A gentle touch with a file at the chamfer angle before finishing the
parting.

Use threading tool to cut the chamfers.

JeffD

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Re: Deburring OD of parted aluminum stock
Posted by: "Shad" shendersonx~xxthegeekgroup.org
Date: Mon Mar 9, 2009 8:47 am ((PDT))

Once I get about 1/16" below the surface of the part, I use a small
triangular file to *CAREFULLY!* chamfer the sharp edge and knock off the
burr raised by parting. I just apply a drop of cutting fluid to the file,
then set it in the groove so it cuts both sides at once. Takes only a
second or so, and when that's done, continue parting off. Of course I
back the parting tool out of the cut before applying the file.

Hope it helps!
Shad H.

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Re: Deburring OD of parted aluminum stock
Posted by: "John Saunders" johnsaundersx~xxpetruspartners.com
Date: Mon Mar 9, 2009 9:12 am ((PDT))

Jeff & Shad - makes perfect sense. For some reason, I had a 'closed
mind' and was only focused on solving the problem after I had finished
parting it off. This solution should work fine.

I will ask though - is there a type of tool which could be useful for
parts which you don't want to chuck in the lathe? For example, I use
this tool - http://tinyurl.com/bk2vuk (the bottom half of the e tool) --
to debur the OD of rifle shells. It works well, but is limited to ~0.50"
in diameter.

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Re: Deburring OD of parted aluminum stock
Posted by: "Rupert" rwenig2x~xxxplornet.com
Date: Mon Mar 9, 2009 9:37 am ((PDT))

Hello John,	I've seen an external reamer in plumbers' tool boxes to
remove the internal and external ridge off pipe. I would check any tool
supplier that carries plumbing tools. A commercial supplier might be
better than the hardware store variety.

Rupert Wenig   Camrose, Alberta, Canada.	
http://users.xplornet.com/~rwenig/Home/

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Re: Deburring OD of parted aluminum stock
Posted by: "Shad" shendersonx~xxthegeekgroup.org
Date: Mon Mar 9, 2009 10:10 am ((PDT))

Hi All,
Depends on the size of the part. If it's small enough, I'll wrap it in
paper then chuck it in a drill and spin it against a file laid flat on
the workbench to break the sharp edge and leave a nice bevel. If it's
too big for that, but has a small-ish bore, I use one of the rubber
mandrels that are for the small Dremel sanding discs. Stuff it in the
bore, tighten the screw, and use the electric drill the same as before.

For parts much larger than that, I'll re-chuck the part in the lathe
(paper or plastic packing to protect the surface) and do it that way.
I find that a good sharp fine toothed file does the job quickly and
effectively. Though usually I try to do it with the work in the lathe
on the original chucking.

As always, be careful using a file on the lathe. Hold the handle (not
the tang, it must always have a handle on the tang!) in your *left* hand
and the end of the file in your right. Yeah, it feels weird. But it's
essential you do that so you aren't reaching over the chuck. It's
fairly chilly now, and you do *NOT* want the jaw of the chuck to catch
your sleeve's cuff. You'll punch the chuck on the way by as it spits
your hand down and backwards, removing substantial amounts of skin from
your knuckles. Trust me 100% on that.

Shad H.

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Re: Cutting bar stock [atlas_craftsman]
Posted by: "Scott Henion" shenionx~xxshdesigns.org
Date: Thu Mar 12, 2009 6:45 pm ((PDT))

CVBT wrote:
> I have a 12" Atlas 3991. I don't have a parting tool yet and I have
some bar stock I need to cut: 1-3/4" steel (6 pcs), 7/8" Al (35 pcs),
1/2" Al (46 pcs). I'm not sure where to find a parting tool holder nor
am I certain I want to invest in one yet, of course that depends on how
much one costs (I certainly buy one for $15, probably for $35, maybe
for $50).  Any recommendations on cutting methods or investments? <

Depends on your tool holder capacity.

I have a QCTP that came with a universal holder for 1/2" blades. IMHO,
you cant go better without going with expensive carbide-insert
blades/holders.

I use 1/6" HSS blades that work fine on softer metals. Cutting mild
steel they will quickly go dull as the metal tends to be grainy. On
12L14 steel or brass and aluminum they work great. I use the HSS bits
only for soft metals and smaller stock.

I have a 3/32 P-type blade that worked great until it shattered (was
already broken once when i got it.) I like the wider blades on heaver
stock as it does not tend to chatter. I am ordering another 3/32 P-type
Cobalt blade.

P-type or T-type blades work better as they have tapered sides. Straight
cutting blades tend to bind (need plenty of lubrication) and they can
wander. The P/T-type are stronger and last longer.

You can get 1/16" x 1/2" blades (about 4 1/2" long) cheap, I have seen
them for $20 on ebay with a holder. The holder will likely be 5/8" so
your toolpost need to be able to hold it. There are some 5/16" tall
blades and holders. they should fit just about anything. The smaller
blades will wander and chatter more (and get hotter.)

Really depends on your toolpost. The lantern holder has limited height
and width. There are angled holders that may work better (look similar
to the Atlas angled tool bit holders.) Most only hold the straight 1/16"
blades.

I have had several cutoff tools. I had some 1/4 tool bits that were
pre-ground to 1/16". You could always grind a 3/8" or 5/16" tool bit
down to 1/16". Works well but only good to just over 1" (5/8" cutter
length). They worked well on my 109 6".

The 1/2" x 1/6" HSS blades i have are OK. I had one from China and it
just would not hold an edge. I picked up two more US made and they work
better (had an Australia-made one that worked good too.)

I really like the one on the QCTP and it is strong and easy to adjust. I
don't really trust the ones that extend the blade out off the side.
Parting is hardest on the tool holder and is most likely to chatter if
your lathe is loose.

I think a HSS 1/16" blade would have a hard time with 1 3/4" stock.
Parting is slow unless you have a real good strong cutter. Also be
careful as the work will easily work loose due to the higher forces.
Larger stock I tend to cut close with a horizontal band saw then face
the edge to length.

Scott G. Henion   Consultant   Stone Mountain, GA
SHDesigns http://www.shdesigns.org

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Re: Cutting bar stock
Posted by: "Russ Kepler" russx~xxkepler-eng.com
Date: Thu Mar 12, 2009 7:42 pm ((PDT))

CVBT wrote:  > I'm not sure where to find a parting tool holder

In your situation I'd suggest simply cutting the stock with a hacksaw and
facing it in the lathe. When you're not sure what you're doing and of the
lathe's capabilities parting is a real PITA. After you blow up a few tools
you get a better feel for it.

At the beginning I'd suggest ginding a 3/8" HSS bit so that there's a
smallish parting blade on the left side of the tool. Try for a tip about
.075" with a slight taper back and a length of 1/2" ot so. There needs to
be some side relief (maybe a degree or so) and something like 5 degrees
on the front. This can be held in a turret or QC toolholder and used to
part small stock. If you blow it up you can always grind another.

If you only have a lantern toolpost you'll have to find a toolholder for
the parting blades. As was suggested earlier the T-type blades are very
nice as they pull the chip together so it doesn't block the cut.

In either case be sure to provide plenty of lubricant to the cut, too much
is about enough. If you get chatter reduce the cut, if it's worse slow
down a tad and increase the feed rate. Watch for the side of the tool
taking a cut - if it does you'll want to get it square before the next
cut. If you're going real deep it's sometimes easier to take a couple of
cuts that overlap by a bit and then part off in the middle of the cut.

-------

Re: Cutting bar stock
Posted by: "Scott Henion" shenionx~xxshdesigns.org
Date: Thu Mar 12, 2009 8:04 pm ((PDT))

Yes, there is a "feel" to it. Parting is where you will break bits and
damage a weak chuck. Keep the belts loose. Don't force it, if you feel
the cross slide get tight, the bit is dull or the wrong height. This is
where you will see the "spring" in the carriage/bed/headstock. Move in a
slight bit and it will cut for many rotations. Move too much, it binds
and the work tries to climb over the cutter.

Once I get down to 1/8", I often just do the last part with a hack saw.
If between centers, as it parts, the tool will get wedged in by the
tailstock force. The smaller the work, the slower it will go. That last
1/8" seems to take forever ;)

If you get the thin HSS bits, get two (should be about $5/ea.) You will
probably break one. ALso nice to have two sharp ones as you can swap out
in one job and not have to stop and sharpen it.

Scott G. Henion   Consultant   Stone Mountain, GA
SHDesigns http://www.shdesigns.org

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Re: Cutting bar stock
Posted by: "Robert Silas" robert.silasx~xxvideotron.ca
Date: Thu Mar 12, 2009 8:12 pm ((PDT))

If I read this right you have to cut through 44.42 square inches of steel
which is equivalent to a bit more than a bar of steel of 6-5/8 x 6-5/8
square. Well, I have experience in this, in both, parting and cutting it
by using a hack-saw. I would not do either. Try finding a friend who has
the cheap Horizontal-Vertical bendsaw (like I have, I would oblige but I
live a bit far from you) and ask him to let you chop-up those bars. Or buy
a used saw on e-bay, at least you would land up with a saw. I had two and
I sold one for 150.

Robert

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Re: Parting off details [sherline]
Posted by: "Ian Newman" ian_newx~xxyahoo.com
Date: Sun Mar 15, 2009 2:28 pm ((PDT))

Hi, First the disclaimer - I do not have a Sherline but I do work with
small lathes - one is a watchmakers lathe of similar size to the Sherline
(but much older).

Any attempt at parting in a machine as small, light and lacking in power
as the Sherline is always going to produce problems and to attempt to
part stock as large as one inch diameter is a truly heroic operation
which puts an enormous stress on the machine - I value the accuracy and
general welfare of my small lathe too much to subject it to that sort
of abuse.

So the first rule of parting in a light lathe is: Don't do it.
The second rule is: Don't do it.
The third rule is: Don't do it.

If you decide to break the first, second and third rules (and let's be
honest, we all do), then here are my comments on your observations:

Check the degree of dishing produced when you face off a piece of bar
- The cross-slide cannot be set at a perfect right angle to the lathe
axis, so the manufacturing tolerances will be such that any errors
produce a slightly dished surface when facing (so a bar faced off will
stand on the faced off end without wobbling).

Keeping the tool vertical is not important (as long as you have some side
clearance) but keeping the top horizontal might be an issue. If the tool
blade is clamped with the tailstock side vertical, it will result in the
top surface of the blade sloping down towards the chuck.  This slope will
be very slight and if it has any effect at all it will tend to push the
work into the chuck and bend the tool towards the tailstock - the
opposite to the effect that you are seeing.

Regarding modifying the tool holder - it may be a better idea to put a
shim or a piece of wire between the side of the tool blade and the lower
part of the tool holder so the bottom of the blade is pushed towards the
chuck.  This will have the same effect as machining the top of the tool
holder, but it will allow you to experiment with the degree of angular
offset.

Ian

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Re: Parting off details
Posted by: "Alan Haisley" alanhyx~xxroadrunner.com
Date: Sun Mar 15, 2009 2:55 pm ((PDT))

I just examined my cut off blade and holder. It turns out that the
P-1-N blade that Sherline sells and their holder are properly designed
so that, installed correctly, the blade will be exactly vertical. The
holder has a recess cut into the clamp area at both the top and the
bottom. This recess is designed to make clearance for the top T section
of the P-1-N blade.

The concave or convex surface comes about because the headstock is not
quite aligned with the bed. If you align the face of the cutoff tool to
either the face of a chuck or to the faceplate, it will tend to feed on
a slight angle. Try mounting the holder aligned with the cross slide
instead (I use a small square to do this) and the action will be better.

Alan

-------

Re: Gear question [actually about parting off] [atlas_craftsman]
Posted by: "Robert Silas" robert.silasx~xxvideotron.ca
Date: Sun Jun 7, 2009 11:16 am ((PDT))

Jim, I don't know how many pieces of alu-rods you are planning to part
off, but if you do it by hand and you are "stepping" the parting process
it's really easy and fast.

By stepping I mean to go forward, let's say 1/4, come back, move the tool
a half of the tool width toward the chuck and go ahead passing the
previous cut by 1/4", then come back move the tool back to original
position and pass the second cut, and so on. Do this till the piece parted
by finishing the last cut on the side which supposed to be nice. Of course
the parting tool has to be ground that its front edge is a bit ahead on
the good side of the job. I hope you can make something out of this.

Robert

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Re: Parting off  - [atlas_craftsman]
Posted by: "doc" n8as1x~xxaol.com
Date: Fri Jun 26, 2009 4:15 pm ((PDT))

Much of the problem in parting off is not putting a proper grind on
the parting tool ...as rcvd, it is NOT ready for use...there is
vertical clearance, but no horizontal clearance till u grind some
relief back of the face., thus tapering back the tool & creating some
clearance for chips. a slight bit of back rake is then ground into the
top of the tool, abt a 4-5 in radius, done on a worn down wheel
...next & maybe even more important is to grind w/ a sharp edged wheel,
a small V on the face of the tool ...this causes the sides of the cut
to be made first & collapse on the center of the cut. the resulting chip
is noticeably smaller now & clears more readily ...after all of this
stone the cutting surfaces...

The lighter the machine is the more these things matter..

If u are into REALLy nasty stuff, & deep cuts,after .150 or so, back off
the blade & cut in .150 on the side of the initial cut. & repeat as u go
deeper, providing a VERY large path for chips...jamups are almost always
from lack of chip clearane. (when the tool holder is on a FLAT surface,
sans rocker)

FINALLY. turn the rocker base upside down, & shim, OR, if needed,
make a proper ht. collar to slip over toolpost, to provide a seat, so
the parting tool holder is firmly on a flat surface..& unable to rock.

Compound gibs shud require some effort to turn ..that's why there are
double knobs on it. & Xslide shud also have some drag, but not a lot.
carriage gibs shud be up to snuff as well for general usage as well...

Best wishes
Docn8as

P S the P shaped parting blade has plenty vertical clearance, but in
other respects still needs to be ground for optimum results..

PPS ..the heavier & tighter the lathe, the more u can get away with
w/ regards to less than optimum grind ...& conversely so ...

Fwiw. I have 6 in & 12 in crftsmn lathes, as well as two 14 in lathes,
the heaviest being circa 2000#......tooled & used when needed......which
is what engendered the PPS statement just above.

-------

Re: Parting off  - upside down and reverse? [atlas_craftsman
Posted by: "David Beierl" dbeierlx~xxattglobal.net
Date: Sat Jun 27, 2009 11:39 am ((PDT))

At 05:34 AM 6/27/2009, MikeA wrote:
>Looking forward to getting my cross-slide extension for rear
>mounting and rear parting tool, but it won't be delivered until
> mid-August! Any other tips on using the rear-parting tool?

I bought one of the small Harbor Freight square toolposts -- I adapted the
cutoff blade holder to take the T-section blade instead of the supplied
tapered one (the Little Machine one didn't exist then). I have Earl
Bower's slotted cross-slide extension and I drilled the blade holder to
take a mounting bolt directly. I made an adapter block of brass to bring
the blade up to the correct height.

When mounting it all I have to adjust is squareness, easily done since the
side of the holder is parallel with the blade. I keep the blade extension
as short as possible, feed the tool vigorously and keep a constant dribble
of cutting fluid (from a Jet-Dry bottle with a blunt 20-ga hypodermic
needle in the cap).

If I get chatter on starting, I stop and turn the chuck by hand while
planing off the bumps until the surface is smooth again; then decrease
rpm or feed more vigorously or both.

I usually dismount the tool when I'm not using it, as it's one more thing
to snag a finger or crash into the work. Since it mounts so easily, this
is little hardship.

David Beierl -- Providence RI USA
Atlas 618 6"/3" lathe ca. 1941

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Re: Parting off  - upside down and reverse?
Posted by: "Jon Elson" elsonx~xxpico-systems.com
Date: Sat Jun 27, 2009 12:56 pm ((PDT))

MikeA wrote:> Hello JT,
> The critical issue I have is the machine just doesn't have the
> rigidity necessary - an Atlas/Craftsman 618. I've gone to thin blades,
> measured to a gnat's eyelash to be sure of perpendicularity and
> centering to the workpiece, used plenty of coolant and still have
> problems.
> The biggest difference in rear mount vs. front is the rotation of the
> piece will cause the front mounted tool to dive and dig into the
> workpiece, whereas the rear mounted parting tool will actually be
> kicked away from the workpiece, thus not digging in.

I had similar problems with 10 and 12" Atlas machines. I think there is
a way to improve the situation by moving the toolpost as far back as
possible on the top of the compound. So, with the compound swivel set
with the handle facing away from the headstock, the T-slot is radial to
the lathe's axis.

You can then slide the toolpost back on the T slot a ways. Always make
sure the toolpost is roughly centered over the swivel by cranking the
compound slide back, too. This gives it the best support. The idea is to
not have the tool tip AHEAD of the center of the compound swivel. If it
is, then a downward force on the cutting edge tips the tool deeper into
the work.

If you can get the cutting tip behind the center of the swivel, or at
least not ahead of it, then downward force won't tip it toward the work.

You can try some of these things and see if they help.

Jon

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Re: Parting off  - upside down and reverse?
Posted by: "catboat15x~xxaol.com"
Date: Sat Jun 27, 2009 1:38 pm ((PDT))

Lots of good advice here from the group. But as someone mentioned the
English Myford is set up to allow a rear mounted tool post for a parting
tool.

Doc sent some good advice also, but I will add a bit, keep the compound
slides tight (too tight to move even) turn the wedge upside down and keep
the overhang of the tool to a minimum. Feed faster than seems proper (in
other words, keep the tool cutting, not skidding). Set the cut off tool
just a "smigin" below the center so it is pushed away from the work, any
set above center and it digs in when deflected.

I usually use the "two step" method, cut a bit, withdraw the tool, move it
sideways a bit and make a groove wider than the tool so the chips don't
jam in the cut.

Now, for the next problem. Where in  the heck did that little part I just
cut off land when it flew away between the ways into the pile of swarf
under the lathe?

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Re: Parting off  - upside down and reverse?
Posted by: "carvel webb" carvelwx~xxabsamail.co.za
Date: Sat Jun 27, 2009 11:51 pm ((PDT))

Umm. . .  Into the baking tray you slid under the ways just before you
started the parting operation? (Seriously - it works . . . )

Carvel

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Re: Parting off  - upside down and reverse?
Posted by: "Gilbert Gileau" gilgilux~xxyahoo.com
Date: Sun Jun 28, 2009 9:37 am ((PDT))

When you get to the bottom of the cut-off.....stop! Shut down, then use
a hacksaw to cut the nib then face off the part you are keeping. The same
way with wood-turning. Don't let that scrap part become a missile....Bam!

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Re: Parting off - upside down and reverse?
Posted by: "Bruce Freeman" freemab222x~xxgmail.com
Date: Tue Jun 30, 2009 7:59 am ((PDT))

On 6/28/2009 Gilbert Gileau wrote:
>> Don't let that scrap part become a missile....Bam!

On Jun 28, 2009, Charlie Gallo wrote:
> Never flys anywhere - just drops off, with a pip, despite having an
angle on the blade - like I said - fairly heavy part. I've been told
I'm doing about as well as I can based upon what I'm parting, but
always looking for a better way. <

I've had this happen on some aluminum parts I've been parting off. I find
I can grap the "pip" with a needle-nose pliers and rotate the pliers and
remove the pip cleanly like a key opening a sardine can. I haven't tried
this on steel.

Bruce   NJ

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Re: Parting off - upside down and reverse?
Posted by: "David Beierl" dbeierlx~xxattglobal.net
Date: Wed Jul 1, 2009 10:47 am ((PDT))

And having that side of the tool slightly ahead so the pip is
undercut slightly helps make sure it comes off clean.

David Beierl -- Providence RI USA

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Re: Newbie question about parting off [myfordlathes]
Posted by: "c j.s" callinicus1953x~xxyahoo.co.uk
Date: Tue Nov 24, 2009 3:16 pm ((PST))

Phil  wrote:
> I have read up on all the info that I have to hand and it only says
use a slow speed and feed and thats what I thought I was doing. I have
an ML7 and was using the slowest speed without the backgear. Can one
of the wise sages here please tell me what I was doing wrong?. I don't
remember parting off being such a problem beforehand. <

Hi Phil: As a general rule you part off at 1/2 the speed you would turn
at. It is generally best to use a lube when parting off, you really can
tell the difference, even if you just drip it on the cut. You must make
absolutely 100% sure your tool is square to the work, if it goes in on
the skew, it will try to bend, not recommended.

There is some debate as to whether the tip of the parting tool should be
on centre or above or below. Aim for exactly on centre, this is more
critical with smaller work sizes, than large.

Personally I like to make the parting tool holder such that it has some
back rake, I use the blade type, of about 6-7degrees. They do cut much
cleaner than the horizontal style.

If you start to get problems, stop cutting and withdraw the tool, then
move it sideways a tad and try again. This will give you a little more
clearance and can help. This is a very useful thing to remember if you
are having trouble parting Stainless. Stainless as you will find out work
hardens alarmingly if you are not brave enough to keep the cut on and by
moving the tool sideways you can cut through this hardening, hopefully.

Others will come in soon with their suggestions. Read them all and try
the various ways, then stick with what works for you.

cj(UK)

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Re: Newbie question about parting off
Posted by: "Steve Ward" zx12x~xxbtinternet.com zx12x~xxbtopenworld.com
Date: Wed Nov 25, 2009 1:58 am ((PST))

I never had any luck parting off, probably because I didn't know what I
was doing. For a long time I'd cut with a hacksaw (whilst the lathe was
in backgear). Then I saw one of these demonstrated.

http://www.greenwood-tools.co.uk/ishop/728/shopscr23.html

It's a tad expensive but an amazing tool. Now I don't bother slowing the
lathe and usually use the power cross feed, no chatter, no squealing
- it just peels the metal off. Easily parts off an inch bar in 10 to 15
seconds.

There are cheaper lookalikes - but at least one that I've seen was
rubbish; whether it's the geometry or what I don't know.

I'm nothing to do with Greenwood but I've found all their tipped tools
to be superb. They claim they're designed with model engineers and
lightweight machines in mind (they would though wouldn't they?) - you may
be able to find the identical tools and tips cheaper elsewhere (I haven't
looked).

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Re: Newbie question about parting off
Posted by: "c j.s" callinicus1953x~xxyahoo.co.uk
Date: Wed Nov 25, 2009 5:01 am ((PST))

Hi Steve, I have heard good reports about the Sandvik / Greenwood parting
tool. There are others that also work just as well, the trouble is you
don't know if they are any good till you try them. Once bought it is too
late. But then if you have nothing to compare them to, you might think
them great. I once bought a different brand at a show and was not happy
with it at all.

The brand I find that does work is Iscar, they had a holder and double
ended tip, which almost halves the price. Trouble is my stock is running
out and, as with such things, they have changed the design, so I might
have to give Greenwood a try.

cj(UK)
PS for those wishing to use a hacksaw in the lathe, please put a piece
of wood on the bed to stop the saw hitting it when you get through. Or
you could put your hand on headstock and your thumb in the frame, to
catch the saw when it get through. All this with the motor OFF.

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Re: Newbie question about parting off
Posted by: "sardinesarnie" sardinesarniex~xxyahoo.com
Date: Wed Nov 25, 2009 11:14 am ((PST))

Hello Phil, and all others.
I loathe parting off, but I usually do it on larger machines.
A few tips, most will be already known, but here goes anyway.
Ensure that you have side clearance on both sides of the tool.
Ensure you have enough front clearance angle.
Keep the tool sharp and dead on centre line.
Keep the tool as near to the chuck/collet as possible.
Grind the top rake angle to suit the material.
Wind in at a constant rate, use power feed if you feel brave!
I use aerosol cutting fluid as a lubricant, and WD40 for aluminium
  (personal choice)
Sometimes coolant can act as a "resistance" to the cutting action in
  that it prevents the tool from biting into the material. Try starting
  the cut without coolant.
Ensure that you have just enough tool overhang to part off the material,
  any more can promote chatter and vibration.
Part off using a rear mounted toolpost if possible.
Ensure that the tool and clamping mechanism are rigid.
An old chuck will tend to have bell mouthed jaws,the workpiece needs
  to be gripped at the front of the chuck for best results. Use a new
  chuck or collets.

Hope this may be of some help.
Regards

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[PARTING OFF]
Tool holders + cut off [atlas_craftsman]
Posted by: "JeffD" jefdaviesx~xxsbcglobal.net
Date: Thu Jan 28, 2010 7:48 pm ((PST))

Hey guys -- I have an old 10F -- I always have trouble with cut off
(parting) -- am using the old lantern ETC...For those of you that have
success, can you give me some recommendations regarding tool holders
and tools? -- I generally order from MSB.

Thanks in advance,
Jeff Davies

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Re: Tool holders + cut off
Posted by: "n8as1x~xxaol.com" docn8as
Date: Thu Jan 28, 2010 8:53 pm ((PST))

first off, a more ridgid set up ....gibs on compound shud require effort
to the slide, x slide shud be free but not LOOSE..carriage gibs shud be
snugged up so it moves freely w/ out shake.....rocker shud be discarded,
the ring turned upside down & a riser added if needed to bring the cutoff
tool to center.....now you can really lock it down ..(this is why buyers
of quick change tool posts are so enthusiastic at better results when
cutting off) ..better option yet than upside down ring is an open sided
tool block w/ a slot for the cut off tool ( or holder & tool ), the
openside block locked to compound w/ a t bolt or bolt/ plate......

now to the cut off blade ....every cut off blade i have seen made from a
square..lathe tool bit has in addition to side & end clearance, a taper
from front to back .....the store bought parting bit is the same
thickness from front to back ..it is not a proper finished bit ...it must
be thinner behind the cuting edge for clearance........AND better yet to
grind a V into the face of the bit ...this causes the sides of the cut
to curl to the center & the actual chip is narrower than the cut, thereby
CLEARING so that jam ups dont occur....cut off speeds shud be 1/3 to 1/2
of normal SFM for the specific diameter .....you may get by w/ a faster
speed on 1-2 ton machines....& on the atlas cfrtsmn, power xfeed is too
fast .., do it manually ....

you do need to use a cutting fluid to clear chips & it needs to be dropped
steadily right on the tip ..i use the dirtiest old engine oil i can find
....black sulfur plumbers thread cutting oil works also ...& lard/bacon
grease cut w/ machine oil or xmission fluid works as well .......problems
in cut off are unwanted movement of the tool, chip jam up, tool not on
center, incorrect speed /feed.....SOMETIMES speeding up feed will help
chatter...usually lowering spindle speed is answer....

you now know what you need ....skill now is to be acquired......

best wishes
docn8as

PS ...P type cut of blades need the same grind as well for trouble free
operation ...particularly w/ difficult steels...there are materials that
you can get away without these xtra grinds, & others that you cannot ....

forgot to add...cut off as close to chuck as possible......also there
are times when using a  t/stock center can help, BUT BE CAREFUL to fully
back off the center well before the final cut ..or you will have a jam
up & a fierce WRECK ....there is judgement here as to when the cut is
deep enuf for a bend or break ....& the center better be out before this
happens.....i hesitated to print this, but there have been times when
the t/stock center was a help in controlling chatter (long thinner piece).

more yet .....a gentle radius ground just back of cutting edge provides
helpful back rake ..i generally put it in w/ a worn grinding wheel,
holding parting tool in line w/ wheel (3 - 4 inch diameter).

-------

Re: Tool holders + cut off
Posted by: "Scott Henion" shenionx~xxshdesigns.org
Date: Thu Jan 28, 2010 11:09 pm ((PST))

> more yet .....a gentle radius ground just back of cutting edge 

I do the same: "hollow ground". Then I finish with a sharpening stone
to hone a fine edge. Cuts like butter.

I use the P-type with a wider top than the blade. Works well.

Scott G. Henion
http://shdesigns.org/Craftsman-12x36/

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Re: Tool holders + cut off
Posted by: "L. Garlinghouse" lhghousex~xxsuddenlink.net
Date: Fri Jan 29, 2010 9:41 am ((PST))

Only one little tiny thing to throw out [up?].

Sometimes I will grind a slight angle on the cutting edge so that the
leading corner of the tool is on the tailstock end. Thus the piece that
is being separated will not have a "tit" at the center because the
leading corner of the cutting edge will sever it. Then I can clean up
the point in the remaining piece by moving the tool in further. The last
bit of cutting sometimes requires a sudden movement to separate the
tailstock end of the piece.

The other posts did a really great job of covering more than I thought
I ever knew.

Later,
L.H. Garlinghouse   The Great White North of Arkansas

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Re: Tool holders + cut off
Posted by: "CaptonZapx~xxaol.com"
Date: Fri Jan 29, 2010 5:38 pm ((PST))

> Sometimes I will grind a slight angle on the cutting edge so that the
> leading corner of the tool is on the tailstock end. 

A good suggestion, but I would warn that on a deep cut, the "not square"
cutting edge sometimes has a tendency to flex the blade in the direction
of the high point. I have noticed it in aluminum, which tends to accept
higher infeed rates.

CZ

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Re: Tool holders + cut off
Posted by: "William Abernathy" williamx~xxinch.com
Date: Fri Jan 29, 2010 10:27 am ((PST))

Parting is difficult. The tool must be sharp, on center, and held rigidly.

1) Snug down the gibs on your compound slide until it's an effort to
turn the screw to advance or retract it.

2) Make sure your tool is square to the work and EXACTLY on center. You
can square it by eyeball, and an easy way to do center it is to lodge a
ruler or fishtail between the tool and the work. If it's vertical, you're
on center.

3) You should only have as much tool hanging out as is needed to get the
job done. When the tool is reaches the center of the work, the holder
should be about to bump into the outside diameter of the work.

4) It is essential that your parting tool is SHARP. Honing the edge with
a diamond sharpener makes a big difference!

5) Use the back gear, and don't stint on the cutting oil.

6) You can do all this with a lantern post if everything is perfect, but
it's easier with a heavier tool holder, such as a quick-change post or a
turret post. You can usually score a quick change set from Enco, Victor,
or CDCO for under $100. It is worth it.

7) (For bonus points...) Grinding a small curve in the top surface of the
parting tool, behind the cutting edge, will make the chips curl inward
and make them less likely to hang up in the kerf. I've never bothered with
this, having had good enough results with 1-6, but if I were in a
production environment, I could see it making a big difference.

William A.

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Re: Tool holders + cut off
Posted by: "Jon Elson" elsonx~xxpico-systems.com
Date: Fri Jan 29, 2010 10:38 am ((PST))

The Atlas doesn't have the rigidity to do cutoff work easily. I know,
because I moved up to a Sheldon R15, a 3500 Lb machine with a carriage
that weighs more than a complete Atlas 10" lathe. But, there are some
tricks that make it just bearable.

1.  Make sure the tool overhang is minimal, and back the compound up so
the T-slot the toolpost mounts to is roughly centered over the coumpound
swivel. This makes the compound much more rigid. Also, if the tool has a
lot of overhang or the post is ahead of the swivel, then sudden increases
in load will cause the toolpost and compound to tilt TOWARD the work,
digging in deeper! Followed by a big bang!

2.  One of the dovetail QC toolposts is more rigid than a lantern post.
But, one of the tricks you can use with lantern posts is to remove
the cup washer and rocker key that sits in it, and shim up the cutoff
toolholder with some tool bits or whatever stock. This prevents the
rocker from slipping under the cutting load.

3.  Make sure the cutting tool is EXACTLY on center with the work. There
are tools you can buy with a fishmouth on one end (open Vee) and a bubble
level. You rest a step on the top of the cutting tool, and the vee against
the work, and adjust the tool height until the bubble is centered. With a
flexible machine, you may want to set the tool a TINY amount high, so it
will be on center under load.

4.  The cutoff blades should have a little valley ground into the top
surface, running along the length of the blade. This makes the chips curl
inward as they come off the cutter. By curling inward, they are narrower
than the kerf, and so don't bind in the cut. If the chips are as wide as
the kerf, you are "bound" to have binding problems.

5.  Use PLENTY of cutting oil.  Huge heat is created in a small area when
parting-off, and that heat causes thermal expansion.  Oil helps reduce the
theat a little, and carries some of it off, too.

6.  Maintain a steady and agressive feed, but then let up and let things
cool while you apply more oil.

7.  The work must be VERY securely held in the chuck, and the chuck jaws
need to be gripping the work along their full length. If your chuck
jaws are worn (bell-mouthed) then you will have huge trouble parting-off.
You need to regrind the jaws, but that is a complete topic in itself.

Jon

-------

Fw: Tool holders + cut off
Posted by: "VBrannick" valestreetx~xxstny.rr.com
Date: Fri Jan 29, 2010 12:49 pm ((PST))

Cut-Off ~ and AWAY she flies. I've found it helpful to insert a support
rod held in tailstock chuck, when cutting off tubular type stock, or a
drilled/reamed support for solid stock.

Vince B.

-------

tool holders / cut off--/2
Posted by: "VBrannick" valestreetx~xxstny.rr.com
Date: Sat Jan 30, 2010 6:47 am ((PST))

In reference to earlier suggestion to use support for cut-off piece,
best to fashion rod/support from non-metal material ~ wood dowel,
plastic... Also good to have a cup for the piece to drop into. Sorry
if this is redundant.

Vince B.

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Re: Tool holders + cut off
Posted by: "jerdalx~xxsbcglobal.net"
Date: Mon Feb 1, 2010 5:54 am ((PST))

>Thanks again, all of you,Particularly DOC, it now makes sense to me, I do
>well with concepts, rather than specifics, and you all have provided your
>time, that I thank you for. As far as Doc hesitating to advise about
>tail stock cut off, Don't worry, I will leave that to Warlocks of like
>kind, in possession of super natural abilities.   Kindest regards, Jef

That warning might have been a bit over-done.

The occurrence of a jam-up if using the tailstock is pretty unlikely with
the sort of parts you are likely to cut off, meaning thinner parts.  The
part will generally drop free and be kicked out of the way by the spinning
part, especially if longer in relation to diameter.

Where you get into trouble is with heavy parts, which of their own weight
may get into a jam, with or without the tailstock. A heavy part can force
its way into a jam where a light part really cannot.

I find the tailstock, particularly if slacked-off, will allow the part to
stay up and finish the cutoff process. otherwise it tends to get off-line,
bending the remaining "stalk" it is attached by, and either cause a jam,
or be knocked off with an unpredictable amount of 'stalk" remaining on the
part and needing secondary operations to remove it. A bit of stabilization
from a slacked-off tailstock center can help a lot..

JT

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Flat or raked part off tools? [mlathemods]
Posted by: "squidsrus85" squidsrus85x~xxyahoo.com
Date: Fri Jul 2, 2010 2:49 pm ((PDT))

Hi All. Many years back I made a few reverse mounted part off tool holders
for 1/2" x 3/32" HSS part off blades for the BD920 lathes.

Which is the better idea for a small lathe, a flat (zero) back rake or the
common 5 degrees? The flat one is easier to set up after sharpening, but
the raked one will probably cut better.

I want to add one to a newer lathe and I only have raked ones left, so I
guess I will start there. But, would love to hear suggestions.

Thanks
Dave

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Re: Flat or raked part off tools?
Posted by: "James Early" j.w.earlyx~xxworldnet.att.net
Date: Fri Jul 2, 2010 2:53 pm ((PDT))

If you use the modern "T" style blade you can run them flat front or back.
If you use the antique style blades that most suppliers sell to the
novices, you need the angle just to make them cut.

JWE   Long Beach, CA

-------

Re: Flat or raked part off tools?
Posted by: "David Beierl" dbeierlx~xxattglobal.net
Date: Mon Jul 5, 2010 7:15 pm ((PDT))

7/5/2010 Monday, jim.klessigx~xxeticonformity.com wrote:
>Ok being one of them novices, what is the difference?

The old-style blades have an elongated V section and an angled bottom
to clamp into a half-vee groove at the bottom of the tool holder. The
T-style ones have a T section with a flat bottom. Because the width of
the blade sharply diminishes immediately below the cutting edge, these
blades offer much better chip clearance.

Yours,
David

-------

Re: Flat or raked part off tools?
Posted by: "Ian Newman" ian_newx~xxyahoo.com
Date: Mon Jul 5, 2010 3:00 am ((PDT))

Hi. If you want top rake on a parting tool, it should be achieved by
mounting the tool at the required angle to the horizontal rather than by
grinding the top of the tool.

The parting tool blade is wider at the top than at the bottom of the
blade (to provide side clearance). If you grind a slope on the top of
the tool the cutting tip will become narrower as the tool is sharpened
and the tip works down the taper. When this happens the tip becomes
narrower than the body of the blade and so the body will jam in the
groove cut by the parting tool.

Ian

-------

Re: Flat or raked part off tools?
Posted by: "James W. Early" j.w.earlyx~xxworldnet.att.net
Date: Tue Jul 6, 2010 6:30 am ((PDT))

Which is why the "T" style blades require only about 20% of the force
that conventional wedge style bladeds do. This is also why they do not
require a heavy rake like the wedge blades do and why they stay sharp
up to 20 times longer. On my CNC at work wedge blades neded to be
sharpened every 3 hours in production while "T" blades were good for up
to 36 hours on the same job. After using the "T" blades for over 20 years
in production work I find it amazing people still waste their money and
time on the silly wedge blades!

JWE   Long Beach, CA

-------

Re: Flat or raked part off tools?
Posted by: "Mert Baker" mertbakerx~xxverizon.net
Date: Tue Jul 6, 2010 6:45 am ((PDT))

I bought all my parting toolbits years ago, and they are all the wedge
type. However, one of 'em is now only an inch long, and I'll get one of
the T type to replace it. Never had any trouble with the wedge type,
once I learned how to sharpen & set 'em properly. Until then, the less
said, the better.

Mert

-------