This is just one of some 80 files about machining and metalworking and useful workshop subjects that can be read at: http://www.janellestudio.com/metal/index.html ------------------------------------------------------------------ Lots of user tips for parting off on a lathe successfully. Parting off (cutting 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 many additional files on my home page Machining and Metalworking at Home http://www.janellestudio.com/metal/index.html SAFETY WARNING BEWARE: DO NOT ASSUME that any subject matter or procedure or process is safe or correct or appropriate just because it was mentioned in a news/user group or was included in these files or on this site or on any other web site or was published in a magazine or book or video. Working with metals and machinery and chemicals and electrical equipment is inherently dangerous. Wear safety devices and clothing as appropriate. Remove watches, rings, and jewellery -- and secure or remove loose clothing -- before operating any machine. Read, understand and follow the latest operating procedures and safety instructions provided by the manufacturer of your machine or tool or product. If you do not have those most recent official instructions, acquire a copy through the manufacturer before operating or using their product. Where the company no longer exists, use the appropriate news or user group to locate an official copy. Be careful -- original instructions may not meet current safety standards. Updated safety information and operating instructions may also be available through a local club, a local professional in the trade, a local business, or an appropriate government agency. In every case, use your common sense before beginning or taking the next step; and do not proceed if you have any questions or doubts about any procedure, or the safety of any procedure. Follow all laws and codes, and employ certified or licenced professionals as required by those laws or codes. Hazardous tasks beyond your competence or expertise should also be contracted to professionals. Let's be really careful out there. (c) Copyright 2003 - 2015 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.

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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

-------

Mounting parting blades for insert tips [MyMyford]
Posted by: "tr0up" a.troupx~xxemail.com
Date: Sun Mar 30, 2008 2:46 pm ((PDT))

I've been meaning to get around to making a suitable clamp adapter
for a parting blade using standard inserts.

They're a bit of a fiddle to arrange on small lathes, so I was
delighted to have my attention directed to a much simpler approach,
typified in the UK by the Kit-Q-Cut from Greenwood Tools. In their
case, a standard blade is cut in half and each end bolted to a plain
rectangular block. This allows the deep blade to be mounted to the
topslide despite being, on the face of it, too tall for the lathe.

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

You may need to click through to "boring and parting tools" and then
select Kit-Q-Cut

I already had the double-ended Seco holder, (the same as Sandvik and
various others) which I'd purchased from a bargain bin some years
ago.
I decided to retain the double ended configuration, and to offset the
block endwise, so one end of the holder gave minimal overhang, and
the other end was suitable for parting large diameters - in my case,
about 80mm.

I marked out a position for the block which would bring the tip to
centre height (what I should have done was to aim to be slightly
high, then mill off the exact amount from the mounting block to bring
it bang on - one end of mine is pretty close, but the other is a bit
low).

I wasn't sure how hard the blade would be to drill, as it's HSS, and
very hard. (Not a cheap Chinese knock-off). I used a couple of solid
carbide drills, one about 5mm for a pilot hole, and 8mm for the bolt.
I possibly ran the 5mm drill a bit fast, at 1000rpm, because the
material around the hole rose to red hot immediately the drill began
to cut ! I've never done this before: my guess is that the high
chromium content depresses the thermal conductivity severely (as with
stainless steel) so the thin blade doesn't conduct the heat away fast
enough. Anyway, the drill didn't seem any the worse, and this "spot
annealing" just made things easier for the 8mm drill, which removed
the ring of blackening. I ran it a LOT slower - about 200 rpm.

These drills work best in rigid setups, and should ideally be held in
collets, in a vertical mill or mill-drill.

I borrowed a carbide countersink, and made a 90deg ring about 1mm
deep at the entry on each side of the blade for each hole, so the
block can be mounted on either side of the blade. Chucking a standard
M8 countersunk socket screws by the thread, I moved the conical face
rightwards, towards the flat end of the screw head, so it would end
up only proud by 1mm from the holder. The head diameter was reduced
to 9mm, but the hex recess was still full depth.

I'm delighted with the result: it's proved a quick way to get up and
running. I can also clamp it in a standard QC holder on my big lathe.
Ideally I'll still make up a rear toolpost for the Myford to suit the
blade, but in the meantime I've got something versatile and eminently
usable for very little effort.

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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.

-------

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.

-------

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/

-------

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.

-------

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

-------

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

-------

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

-------

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

-------

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

-------

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/index.html" lathe ca. 1941

-------

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

-------

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?

-------

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

-------

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!

-------

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

-------

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

-------

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)

-------

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).

-------

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.

-------

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

-------

[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

-------

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/

-------

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

-------

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

-------

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.

-------

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.

-------

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

-------

[Actually the discussion is mostly aboout parting off.]
Re: QC toolholder [myfordlathes]
Posted by: "boz_oxon" melodycsaxx~xxyahoo.co.uk boz_oxon
Date: Sat Jun 26, 2010 2:38 am ((PDT))

I thought I'd resurrect this old thread to append a "what actually
happened" post for completion's sake.

So far, after help and encouragement from others here, I'd bought a
Chronos "ML7 etc" QC toolholder to fit it to my ML2.

I've mounted it to the cross-slide (due to the lower centre height than
an ML4 or later). I've used a length of 2" square brass, cut and faced
to 26.0mm long as a spacer, with a 10mm hole drilled though the centre.
A new 75mm T bolt was made, with the thread cut to 5/16 BSW to match the
existing clamp nut that came with the toolholder (luckily I already had
a matching die). With this in place, I can align all my tools (6-13mm
size) as well as the included parting tool to the right height. At the
extremes I still have over 2mm of adjustment available, so the spacer
height seems about right.

It works very well. Excellent value for money. So much easier to align
tools. Nice and rigid, easier to swap tools. I haven't tried parting off
yet however, still plucking up courage!

Boz

-------

Re: QC toolholder
Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com alan4227
Date: Sat Jun 26, 2010 3:23 am ((PDT))

Dear Boz, For stress-free parting off you would be better off with the
rear toolpost. There are several designs for this for the ML7, but I'm
not sure what you would need to change to fit one to the ML2. Not sure
if the cross slide is long enough to take it. Another project?

Regards,
Alan

-------

Re: QC toolholder
Posted by: "DAVID WILSON" d.j.wilsonx~xxmac.com dave20thmay
Date: Sat Jun 26, 2010 3:59 am ((PDT))

For my two pence, You will find the QC tool holder with the blade that
came with my kit works great. On my ML 4, where I went to the trouble
of making a rear tool holder, I never found any benefit, due to length
of cross slide. So try a nice sharp tool, square to the job and not
some tool steel that you would not normally be parting. Give the ally
and brass a go. Mine worked better than any parting tool I'd used in
the 40 years, I've had the lathe.

Also make a dural bar Tangential tool holder, with a nice depth setter
for instant height setting and you'll find the lathe transformed. I
think I've some photo's in my ML 4 Tumbler Reverse Album.

Dave

-------

Re: QC toolholder
Posted by: "Andy Chapman" Chapmanadx~xxaol.com chapmanad
Date: Sat Jun 26, 2010 5:20 am ((PDT))

For really trouble-free parting off, I use a Glanze indexable parting
blade with replaceable cutting tips. It knocks spots off an HSS blade
whether it is mounted at the front or the back. In fact, I no longer use
my rear tool post for parting off because it gives no further improvement.

Parting off a 1" titanium round bar was like cutting through cheese and
I frequently use it on high-grade stainless with no issues at all. I
bought the tool at a modelling engineering exhibition last year and have
never looked back.

AndyC

-------

Re: QC toolholder
Posted by: "Steve Ward" zx12x~xxbtinternet.com zx12x~xxbtopenworld.com
Date: Sat Jun 26, 2010 5:50 am ((PDT))

Ditto the Greenwood parting tool.

I do on the other hand use the rear toolpost, mainly because I can just
leave the parting tool set up in it, do my machining then just wind the
crosslide forward and bingo!

-------

Re: QC toolholder
Posted by: "john56552" john.777cordenx~xxbtinternet.com john56552
Date: Sat Jun 26, 2010 11:18 am ((PDT))

Hi Dave, I like your tangential tool holder. Do you have drawings for
this?

John

-------

Re: QC toolholder
Posted by: "MikeD" durnfjmx~xxaol.com durnfjm
Date: Sat Jun 26, 2010 11:35 am ((PDT))

Is the Greenwood the same as the Kit-Q-Cut? If it is I can wholeheartedly
agree with that recommendation. I bought one 5 or 6 years ago, mounted it
in the rear toolholder (S7B) -- use it all the time, and haven't even
replaced a tip yet, even though I bought a couple of spares at the time!
As a keen boater, I use a lot of 316H stainless, which can be difficult
to machine, but I recently parted off 8 off 50mm diameter washers from
the stuff for a friend with absolutely no problems, the only cutting fluid
I use is neat oil applied with a small paintbrush.

Y'all get out of your shops and enjoy the wonderful weather!

MikeD   Pembrokeshire, Wales.

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Re: QC toolholder
Posted by: "DAVID WILSON" d.j.wilsonx~xxmac.com dave20thmay
Date: Sat Jun 26, 2010 11:38 am ((PDT))

Hi John.
I made it to the size of metal I had. Your lower centre height will have
to be allowed for. On monday when I'm next down the workshop where we use
the lathe, I will run a rule over it. Metric or Imperial????

This works really well and does not need to be made in steel at the
moment on mine. But will have to see how the sizes work on yours to see
if you would benefit by making it in steel.

David

-------

Re: QC toolholder
Posted by: "john56552" john.777cordenx~xxbtinternet.com john56552
Date: Sat Jun 26, 2010 11:44 am ((PDT))

David, Thanks for the speedy reply. I have a Super 7 with Chronos/RDG
Dixon style QCTP -- similar to yours by the look of it. The lathe is
imperial so it's easier to work that way, although I'm trying to 'go
metric'in the long term(!)

John

-------

Re: QC toolholder
Posted by: "DAVID WILSON" d.j.wilsonx~xxmac.com dave20thmay
Date: Mon Jun 28, 2010 10:08 am ((PDT))

Hi John
Have just downloaded a bit of video of the tool in use. For such an old
lathe as mine, I think that this is impressive.

This link to this on You Tube is
http://www.youtube.com/watch?v=osVmqVcbgts

I will send you the information on the sizes later. The basics of the
tool holder is from Model Engineer (Workshop) If I can find the link to
the page and it is still there to open, I will send it to you. If you
could have a check for yourself that would be helpful.

Dave

-------

Re: QC toolholder
Posted by: "john56552" john.777cordenx~xxbtinternet.com john56552
Date: Mon Jun 28, 2010 12:17 pm ((PDT))

Very nice Dave, thanks. I'll have a look in MEW for the article.

John

-------

Re: QC toolholder
Posted by: "DAVID WILSON" d.j.wilsonx~xxmac.com dave20thmay
Date: Tue Jun 29, 2010 8:02 am ((PDT))

Hi John.
Have just redone the the video with my Oly. Pen and the link is here.
http://www.youtube.com/watch?v=EsrNLHHidlU

Dave

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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

-------

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

-------

[The subject is mainly parting off in a lathe.]

Backgear backlash--Atlas10F [atlas_craftsman]
Posted by: "Tazwell" tazwellbramlettex~xxyahoo.com
Date: Thu Jan 13, 2011 11:37 am ((PST))

When the backgear is engaged I have 1.8 degrees of backlash when the chuck
is rotated by hand. When the chuck is rotated in the direct drive mode,
the runout is +/- .0005. When running the gears are loud, with a "bell-
like" sound. The backgear shims are .008. I am using a multi-purpose
lithium grease. Even at the slowest rpm possible (70 rpm) there is chatter
when trying to cutoff 1.5 inch metal pipe of unknown composition from
Lowes. What are an appropriate backlash, grease and rpm for this
operation?

-------

Re: Backgear backlash--Atlas10F
Posted by: "Scott Henion" shenionx~xxshdesigns.org
Date: Thu Jan 13, 2011 11:56 am ((PST))

The "bell like sound" is usually the drive pulley hitting the bull gear;
usually due to worn bushings. I replaced the pulley bushings on mine and
the ringing went away.

There will be considerable backlash when using the back gear.

I use higher speeds for cutting off, slow allows cutter to chatter.

Scott G. Henion
Craftsman 12x36 lathe:
http://shdesigns.org/Craftsman12x36

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Re: Backgear backlash--Atlas10F
Posted by: "James Irwin" jirwin1x~xxaustin.rr.com
Date: Thu Jan 13, 2011 12:37 pm ((PST))

This brings up my main interest in the VFD drive idea. One can vary
spindle speed dynamically to remove chatter while a cut is proceeding.

Jim I

-------

Re: Backgear backlash--Atlas10F
Posted by: "Jon Elson" elsonx~xxpico-systems.com
Date: Thu Jan 13, 2011 6:46 pm ((PST))

The backlash in your backgear is surprisingly low! Most are worse. The
bell-like sound is the 4-step pulley dinging against the spindle.
The bushings on the pulley are a classic wear point. You should put oil
in the setscrew hole in the pulley before using the backgear.

The chatter is not likely to be from the backgears, but the tough
material. You need to set the compound rest near the center, and get it
as close to the work as possible. Any excess overhang of the tool creates
a lever arm for the cutting forces to twist the lathe.

"Unknown composition" is likely the biggest problem, this stuff is
electrically resistance welded from rolled-up sheet, which leaves a very
bad heat-affected zone. Dark cutting oil is best for cutoff operation, and
you want to use the thinnest cutoff blade you can. Wide cutting tools tend
to cause chatter on lathes that have much spring, like the Atlas. I was
never able to do cutoff work on a 10" Atlas without a lot of problems. It
was a little better on the 12" Craftsman I later had, with the 1/2" thick
ways. Even with the 3500-Lb Sheldon 15" lathe I have now, it can be tough
sometimes. But, rigidity really is helpful when parting-off.

Jon

-------

Re: Backgear backlash--Atlas10F
Posted by: "George Smith" technosmitx~xxyahoo.com
Date: Thu Jan 13, 2011 9:10 pm ((PST))

Something worth checking. I recently went through a 10" this summer and
had a lot of noise in back gear. What I originaly found was that someone
installed new bushings in the 4 step spindle pulley wrong (both bushings
were pushed together on one end and blocking oil feed hole) and when I
repaired them, I didn't press the one on the left side of that pulley
(gear box end) in far enough so the mesh between the small gear on the
spindle and the 4 step on the spindle was loose and it made a lot of
noise. I corrected the bushing position and the freeplay between the two
and the lathe is quiet now. It's worth checking.

-------

Re: Backgear backlash--Atlas10F
Posted by: "speedphoto300" speedphoto300x~xxyahoo.com
Date: Thu Jan 13, 2011 9:34 pm ((PST))

Finding both bushings at one end of the 4 step pulley is not unusual, and
is not the result of a bad installation job, but rather the result of
asymmetrical force on the pulley by the belt tension. Over time this
causes one bushing to walk to the other end of the pulley bore.

Joe

-------

Re: Backgear backlash--Atlas10F
Posted by: "Glenn N" sleykinx~xxcharter.net
Date: Thu Jan 13, 2011 10:14 pm ((PST))

First I wouldn't be in back gear to cut that pipe. I usually part at the
same RPM I am turning to size with. Dovetail the parting tool and hone it
well. Use lots of cutting fluid. I like 50/50 ATF and kerosene for general
use.

The backlash on the backgears is set the same way the change gears are. A
piece of typing paper should roll through with some resistance. Have you
read the lathe bulletins on the clausing website?
http://www.atlas-press.com/servicebulletins.htm

If you have too much backlash and ringing gears it sounds like worn or
misaligned bushings in the pulley cluster. Definitely do not run an
interrupted cut in back gear with the backlash sloppy as you will eat
teeth. I don't do any interrupted cuts in backgear. In fact about the
only thing I use backgear for is threading really coarse threads cause
I'm chicken LOL. It would cut better if I could move fast enough to run
in a belt drive speed...

Glenn

-------

Re: Backgear backlash--Atlas10F
Posted by: "jerdalx~xxsbcglobal.net"
Date: Fri Jan 14, 2011 5:46 am ((PST))

Pipe is "mystery metal" and can be very gummy and nasty to cut. A loose
machine, with wear, sloppy gibs, etc, or just a very lightweight machine,
can add to the tendency to chatter.

Tool and holder design is another issue, if the tool "nods" and digs in
deeper, it is going to chatter. If down force makes it swing AWAY from
the work, then chatter is a lot less likely.

While chatter isn't "caused" by speed, cutoff often is made worse by
higher speed. Slowing down can fix it. If you can go very fast, chatter
may be reduced/eliminated that way.

But "middle" speeds often are the worst for chatter in any operation. Slow
enough that you take a sizeable depth of cut, fast enough to put enough
energy into the system to have chatter.

If you have a single phase motor, you are likely stuck with chatter, on
any lightweight machine. It is a function of the huge torque variations
in most single phase motors. The turning speed is likely to make it worse
if the speed is around 60, 120, 180, 240 etc rpm, which are harmonics of
the 60/120 Hz "torque ripple" frequency*, and will push the system into
chatter even if it wasn't quite "there".

If you go three-phase, then everything the books say works. Same if your
machine is very massive, which Atlas machines are definitely not.

Slow down below 70 rpm and you may be fine. If you can run very fast, you
get above the frequency that the machine can vibrate at.

JT

* while the base torque ripple is at 120Hz, there is also a 60 Hz
variation because motors are rarely well balanced. Usually the torque
varies during one revolution due to mechanical off-center in the rotor.
That is added to the 120Hz electrical torque variation.

-------

Re: Backgear backlash--Atlas10F
Posted by: "toolmaker48" toolmaker48x~xxyahoo.com
Date: Fri Jan 14, 2011 9:57 am ((PST))

Hi,
1 Cut-off as close to the chuck as possible.
2 Keep the overhang of the tool as short as possible.
3 Any speed is OK as long as you can keep up with the chip.
   .001 to .003 per rev. Once you pick up the chip, keep going.
   If you have to stop, pull back the tool.
4 Once it starts to chatter, you're pretty much done.  :(  A real bear
   to get rid of the chatter after that.
5 Keep the tool oiled. Don't be cheap. I use thread cutting oil.

Robert

-------

Re: Backgear backlash--Atlas10F
Posted by: "Doc" n8as1x~xxaol.com
Date: Fri Jan 14, 2011 2:03 pm ((PST))

fwiw .. on my late model 12x36 crftsmn ..i ususally start at abt 1/2
normal turning speed for 1018 (mild steel)...then increase as allowable
...on deep cuts, it helps to back out & cut in on either side, giving
plenty room for clearance....FRONT TO BACK clearance (cutting edge wider)
is VALUABLE,,,also a V ground in face of tool collapses the chip & a
smaller chip energes.....a gentle 4-5 inch back rake radius ground in
w/ circumference of your stone..is helpful.

i use old engine/tractor oil, dirtier the better ..FLOOD it ..(think it
is full of sulfur, but so far cant get a chemist to verify).....prefer
bacon grease, lard, crisco, lard-30wt non deterg, for thrding ...dirty
black engine oil also works.

..FWIW every parting tool bit ground from a lathe bit, that i have ever
seen, had PLENTY front to back clearance..unlike commercial blades,
which i think are UNFINISHED !!!!!!.....most important is a SOLID base
....turn your female rocker OVER & add washers if nothing else....
opensided bit holder blocks are even more solid than QUick change ....
just bolt them down w/ a t bolt or plate, cut a slot on side & grubscrews
on top..... atlas crftsmn cross slide, unlike heavier machines is the same
feed as longitudinal & is TOO FAST FOR USE on my machine (& yours )
....heavier ones have 1/2 the longuitudinal feed on the xslide & power
cut off is useful when EVERYTHING ELSE IS RIGHT.

best wishes
docn8as

-------

NOTE TO FILE: Those who have had trouble with parting off with a lantern
style toolholder may learn something from Doc's next message. Those
who have only a lantern style tool holder for their lathe will benefit
particularly from a discussion in the file here called "Toolholders For
Lathe" starting Feb 4, 2012 and titled "Tool post washer" which contains
information to improve the performance of the lantern post for other
operations too.

-------

parting off  w/ lantern tool post [atlas_craftsman]
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Wed Feb 15, 2012 9:01 pm ((PST))

FWIW ....building a stdy rest for an antique barnes ....needed three
.125 X 1 inch heavy washers for 5/16 & 18 bolts.....using crftsmn
commercial 12x36, chucked a one inch bar of 1018 steel in 3jaw, cleaned
it up, faced, & drilled w/ center drill, & 19/64 followed by 5/16.....
removed the turret & its T plate, because the fixed parting bit on one
position was for smaller things .... put the lantern tool post on w/ OUT
wedge & dished washer....put the thick flat washer over the tool post,
which puts the gooseneck parting tool on center & wrenched it down ....
bit was commercial w/ built in side clearance & i ground in front
clearance, & a V on the FACE & a 3 inch radius back rake PLUS back draft
(front of bit tapered a tad toward the rear)....i was turning the bar,
using a speed of circa 266 because next speed was a bit high .....
i started parting at the SAME SPEED, instead of reducing it as i ususlly
do to hold down chatter .....tool squeaked a bit but soon quieted as i
hand fed it ...cut smoothly, w/ no chatter nor hangups of any kind till
the part fell off...swarf came off as ribbons of steel narrower than
the cut ....& here, i guess is the point: ...NO FLUID OF ANY KIND WAS
USED ..!!!!! i am not advocating this, just reporting, but it sure was
nice w/ out the MESS!

dont know how much was due to the flex, or the V collapsing the width of
the cut ..probably both ...

i had a solid parting tool in an openside block & shud have checked w/
that to see the difference, but i was just interested in making washers
at the time ......at any rate the lantern tool post was dead steady
w/ the fat washer under the parting tool.

armstrong S-30 or williams S-20 shud work for atlas crftsmn 10& 12 inch
lathes.

best wishes
docn8as

-------

Re: parting off  w/ lantern tool post
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Thu Feb 16, 2012 12:21 pm ((PST))

Feb 16, 2012 Deloid  wrote:
> I really liked this post. This supports the concept of a solid washer
that has been advised. I would really like to see that parting bit as I
am a "visual learner". Any part number I can look up? Did you take a
photo of your setup? Thanks Dean <

Deloid .....sorry, i dont have a pic ... if i ever take some more pics,
i can send jpegs of them to someone who could post them.

the bit was a standard parting tool bit that arrived w/ side clearance
ground in the whole length ...i ground some front clearane & then a V in
the VERTICAL face was ground on the edge of a grinding wheel (if the edge
is sharp)..be sure you dont lose your front clearance when you grind
the V.   the V just needs to be near the top. but at the the same
clearance angle .....back rake (on top from front to rear was put on
w the peripheral edge of the wheel, giving a gentle 3 inch radius ...
NOW i ground some additional clearance front to back, meaning that the
parting tool was a TAD narrower one in back than it was at the cutting
edge ...this again gives clearance front to back so the bit doesn't
wedge ......this & the V are to narrow the chip allowing it to move out
w/out jamming the bit ...& the fact that it did W/OUT any clearing fluid
seems to prove that ......(that said, fluid is a safety measure)..

if you pick up a copy of burghardt machine tool operation vol 1 i think
there are some forged & ground parting bits there, showing front to back
clearance, although not w/ the V.....$10 shud buy a copy & any edition
...starting around 1921 ...dont know if 1940 (later 0 editions have
these pics)....as you move on, vol 2 (shaper, mill, planer, grinders) is
also of great value......it is more suited to the needs of HSM's than
current texts.

best wishes
doc

-------

Parting problem [myfordlathes]
Posted by: "djmorrow2004" djmx~xxldrider.ca
Date: Mon Mar 26, 2012 9:34 pm ((PDT))

I am cutting fins for a Stirling engine in a piece of 3.50" diameter
aluminum with a .094" parting tool. The cut is about .50 inch deep.

The problem that I'm having is that the slot that I end up with is wider
than the parting tool. As the parting tool enters the workpiece it's
bending ever so slightly to the right which is making one side of the cut
slightly tapered. ( This feels like I'm trying to describe a colour.)

I suspect that as I was making the first part of the cut, the top slide
was moving without me noticing it and the parting tool was moving slightly
to the right, all the while shaving a tiny bit off that side of the slot
each time.

The top slide is set at about 45 degrees to the cross slide and I suspect
that I should set it at 90 degrees or 0 degrees. I'm a bit reluctant at
this point to go too much further as I can't afford to screw up this big
lump of aluminum.

-------

Re: Parting problem
Posted by: "Boz" melodycsaxx~xxyahoo.co.uk
Date: Mon Mar 26, 2012 9:45 pm ((PDT))

I've had this problem, when parting brass, with one of my "blade"
parting tools that had an angled end face. I sorted it by regrinding the
end to a symmetrical shape.

Boz

-------

Re: Parting problem
Posted by: "djmorrow2004" djmx~xxldrider.ca
Date: Mon Mar 26, 2012 10:38 pm ((PDT))

I couldn't leave it alone so I went down to the shop and turned the top
slide to 90 degrees which helped some. And then... I resharpened my brand
new parting tool from an angled face to a square end. Much, much better
now. Great minds think alike apparently. Thanks so much for confirming
that at least part of my approach to the problem was the right one.

David

-------

Sherline cutoff blades [SherlineCNC]
Posted by: "Andrey Lipavsky" andreyx~xxessexjewelers.com
Date: Sun Jun 24, 2012 12:42 pm ((PDT))

I need some advice on replacement cutoff blades for my 4400 lathe. My CNC
setup went nuts today, as sometimes happens, and snapped the cutoff blade
while driving it into the rotating stock at G0 speed. In any case, do any
of you guys use anything other than the standard Sherline 0.040" blades.
I came across some 0.0625" units online. They're much less expensive than
the Sherline blades, but thicker. Any thoughts or comments would be
appreciated.

Thanks,
Andrey
www.EssexJewelers.com

-------

Re: Sherline cutoff blades
Posted by: "Scott Meyer" baldysmx~xxyahoo.com
Date: Sun Jun 24, 2012 12:49 pm ((PDT))

I personally don't like the Sherline blades. They are too thin and weave
back and forth way too easily.

Thicker is better (up to a point).

Scott Meyer
http://www.onlyonecreations.com

-------

Re: Sherline cutoff blades
Posted by: "Alan Marconett" KM6VVx~xxSBCglobal.net
Date: Sun Jun 24, 2012 1:26 pm ((PDT))

That was my experience yesterday. The blade flexed too much before getting
very deep. Didn't break, but I gave up and used a hacksaw. Aluminum stock,
1.5" diameter. Easy also to do cutoff with bandsaw.

Alan
DE KM6VV mobile

-------

Re: Sherline cutoff blades
Posted by: "alighazizadeh" alighazizadehx~xxaol.com
Date: Sun Jun 24, 2012 2:54 pm ((PDT))

Hi, I use the blade that came with my Taig/Peatol lathe with a homemade
rear mount tool post, on my Sherline 4500 and it works fine. The blade
is made in India and is 1.6 mm thick at the cutting tip. I have managed
to part off 30 mm diameter mild steel bar with no difficulty so long as
the blade is super sharp. I have also purchased some cheap German made
hss blades but as yet have to used them extensively but they seem to be
fine. The strange thing is that the indexable carbide parting off tool
that works really well on my Taig lathe does not work so well on the
Sherline for some reason.

Regards,
A.G

-------

Re: Sherline cutoff blades
Posted by: "Martin Dobbins" trainnutzx~xxyahoo.com
Date: Sun Jun 24, 2012 4:01 pm ((PDT))

Alan, Scott, Andrey
Rear mounted toolpost? Blade in correct orientation (upside down for
rear toolpost). Blade parallel to work? Blade dead on center? Minimum
stick out of blade from the toolholder? Spindle speed slow enough? Feed
high enough? Plenty of lubrication?

Maybe I've been lucky but I've MDI'd 1.5" diameter 1018 with very little
cleanup required afterwards. I haven't tried anything tougher yet.

Martin

-------

Re: Sherline cutoff blades
Posted by: "timgoldstein" timgx~xxktmarketing.com
Date: Mon Jun 25, 2012 5:39 am ((PDT))

The standard .040" wide blade is called a P1N in industry terms so if you
search on that you may find more options. Little Machine Shop has a
Chinese version for under $10 :
http://www.littlemachineshop.com/products/product_view.php?Prod
uctID=1930&category=

This is actually the blade we designed our QCTP for. If you are parting a
1-1/2" diameter it is not a good solution, but then again doing this on
a Sherline is really pushing the capability. Not that it can't be done,
but a Sherline chuck just doesn't hold something that big very rigidly and
there is a high likelihood of the part moving and the blade breaking.

The reason we recommend this thin blade is because the cutting load is
much lower than a 1/16" blade (more than 50% greater load) and the biggest
issue when parting is chatter from tool and part flex. On the smaller
sized items most people machine on a Sherline the stock will flex and
climb the cutoff blade and start chattering. Only way to reduce that is
part closer to the chuck or use a tool that does not put as much pressure
on the part. The thinner blade really help keep the part flex down.

Tool flex is not really a major issue on a Sherline as there is not enough
HP to deflect on a continuous load basis. It only kicks in when the part
is climbing the blade or you have the blade out so far that it will never
be rigid.

Just to give a little idea, we part on our Haas (20 HP continuous, 40 HP
peak) with a 3 mm wide blade with feed in aluminum of .004 - .007" per rev
on anything from 3/8" stock up to 1-1/2" stock. So on a Sherline with
about 1/100 the power, using a wide blade is major overload and will cause
part flex and chatter long before the capacity of the blade is exceeded.

Chatter is what kills you and a wider blade only makes matters worse when
the flex is in the part or setup and not the tool deflection.

BTW, we do sell both a USA made HSS version and a brazed carbide micro
grain version of the P1N .040" blade. Could make a lot more money selling
the wider blades, but don't because we feel they are not appropriate for
most uses on a Sherline.

Tim Goldstein
A2Z Corp   3955 S Mariposa St   Englewood CO 80110
P 720 833-9300 M-F 10 - 5 Mountain
www.A2ZCorp.us/store

-------

Cut off tool [myfordlathes]
Posted by: "Ali Ghazizadeh" alighazizadehx~xxaol.com
Date: Tue Nov 20, 2012 12:13 pm ((PST))

Hi To All, I know it may sound silly but what type of cut off tool would
you recommend for a Myford Ml7 of 1949 vintage? I mostly work with
aluminium, brass and EN1a up to about 40 mm diameter.

Regards,
A.G

-------

Re: Cut off tool
Posted by: "Robert Mitchell" rmm200x~xxyahoo.com
Date: Tue Nov 20, 2012 12:39 pm ((PST))

I have always used the Eclipse line of cutoff tools. They have a narrow
kerf and are hollow ground so the tend to not jam in the cut.

This is a (large) Eclipse catalog. Only download it if you don't mind
large:
http://www.spear-and-jackson.com/sitefiles/neilltools/low%20EC
LIPSE%202012.pdf

The cutoff blades are on Page 77. You can find them for sale on EBay
for cheap.

You can get carbide cutoff blades, along with carbide everything else,
but for model engineering I really think you learn a lot more by using
HSS. It forces you to learn a bit about tool geometry, and how to
sharpen cutters.

That said -- I reach for my inserted bit carbide lathe tool when I just
want to remove some metal.

Robert Mitchell

-------

Re: Cut off tool
Posted by: "alighazizadeh" alighazizadehx~xxaol.com
Date: Tue Nov 20, 2012 1:05 pm ((PST))

Hi Robert, I do have some spare Eclipse blades somewhere. I think they
are 1/2 x 1/16 X 4". I may have one with 5/16" width too. I have only
recently acquired the lathe and the bench is not sorted yet.

The best cut off tool that I have had for my little Taig lathe is the
rear mount tool with a P1 type blade but I don't seem to be able to
source the P1 type in the UK.

Thanks for all your replies.

Regards to all
A.G

-------

Re: Cut off tool
Posted by: "Paul Kennedy" clankennedy2004x~xxyahoo.co.uk
Date: Tue Nov 20, 2012 12:45 pm ((PST))

Hacksaw. Brass and Alloy are soo soft and it's only 40mm. By the time
you dig out the parting tool, set its height, I could have sawn it off
with a hacksaw + you're saving money for a good bench ! or other item !

-------

Re: Cut off tool
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk
Date: Tue Nov 20, 2012 3:09 pm ((PST))

Q-cut.

David Littlewood

-------

Rear toolpost - ML7 [myfordlathes]
Posted by: "garthn444" garthnx~xxpbt.co.za
Date: Tue Mar 19, 2013 6:40 am ((PDT))

Hi. I've put a photo into "Rear toolpost - ML7" - my first attempt at some
real swarf making. Parting is definitely easier now although the tool is
still slightly high.

But I could not use the holder as I am sure it should be used, due to lack
of space - so I have cut it and mounted it "backwards". Problem - the tool
is not well supported enough now - it moves slightly laterally even though
the holder is dovetailed. I parted a 1/2 bolt but I think the blade is
close to breaking.

I'm thinking of making a horizontal cut in the back of the holder so it
will pinch the blade when the cap screws are tightened.

Does anyone have a better idea? This is someone who has never previously
cut steel thicker than 1/2" - I'm not expected to end up with a commercial
equivalent.

-------

Re: Rear toolpost - ML7
Posted by: "Robert Mitchell" rmm200x~xxyahoo.com
Date: Tue Mar 19, 2013 7:18 am ((PDT))

For parting off, the tool tip must be exactly on center line --
not slightly high or slightly low.

Use a good quality parting blade, sharp, correct angle, and in good
condition.

The tool should protrude from the holder only slightly more than the
radius of the part being parted, for maximum support.

The tool must be oriented exactly perpendicular to the axis of rotation
(go straight in).

Use slowest direct drive, and use power cross feed if you have it.

Follow these on a light lathe like the Myford, and parting will be only
slightly exciting.

Robert Mitchell

-------

Re: Rear toolpost - ML7
Posted by: "garthn444" garthnx~xxpbt.co.za
Date: Tue Mar 19, 2013 7:43 am ((PDT))

As a newbie, I already knew that - although Sparey advocates perhaps
setting the tip very slightly below centre line. But I will in any case
face the blocks off until I am exactly at centre and give it a good trial
like that.

I was asking about getting the holder to grip the blade properly (now that
the holder is reversed). I could try shimming inside the holder etc but
that seems certain to be a hassle.

So does a slit in the holder seem good? I can't see too much of a problem
except that I would have to loosen the cap screws to move the blade --
when the holder already has a wedge.

-------

Re: Rear toolpost - ML7
Posted by: "Nigel Heasman" nigelx~xxnigelheasman.com
Date: Tue Mar 19, 2013 8:15 am ((PDT))

Hi Garth, your idea of a horizontal slit so that the cap screws clamp
the blade,  at the business end, could well help - worth a try!

Also, the parting action is trying to separate your holder block from
the mounting block -- does the bottom end of the long stud, that holds
the two blocks together, go into a T slot on your cross slide? Can you
beef up the stud size to get maximum rigidity?

Good luck
Nigel

-------

Re: Rear toolpost - ML7
Posted by: "garthn444" garthnx~xxpbt.co.za
Date: Tue Mar 19, 2013 9:45 am ((PDT))

Hi Nigel, I went ahead and slotted it - feels much sturdier. I haven't
tried using it yet.

The two blocks clamp together solidly - the bolt does indeed go into a
T slot. Not sure what the bolt is, but it seems to be high tensile. It was
quite tough to turn and grind. It had a hex cap head - I'm glad I didn't
use my original idea of a galvanised bolt that was completely threaded.

I'm also glad I used mild steel (as I was advised on this site) instead
of aluminium - besides the actual blade, it has turned out to be rock
solid - and heavier than it looks too.

Thanks
Garth

-------

Re: Rear toolpost - ML7
Posted by: "Nigel Heasman" nigelx~xxnigelheasman.com
Date: Tue Mar 19, 2013 10:48 am ((PDT))

Hi Garth, glad to hear it feels sturdier - I found that parting off was
the "worst" part of machining on the ML7 until I bit the bullet and bought
a Kit-Q-Cut tool from Greenwood Tools.
http://www.greenwood-tools.co.uk/shopscr23.html

Now I actually enjoy it! It's a wonderful piece of kit. If you look at
the picture in the link, you will see how very well supported the cutting
insert is from below - it makes for a very robust parting off tool, in
the regular tool post.

I even use it for small turning cuts before parting off - saves changing
the tool for a small trim of a diameter!

I've no connection with Greenwood tools apart from being a very satisfied
customer.

Good luck,
regards
Nigel

-------

Re: Rear toolpost - ML7
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk
Date: Tue Mar 19, 2013 3:55 pm ((PDT))

I would second that - best parting off tool I've ever used, and does
away with the need for a rear toolpost. Works fine in a Dickson holder
from the front.

I have a larger version (i.e. similar TC tip shape) for my larger lathe,
which parts off under power with no problem. It's the tip geometry which
makes it so effective, as well as the support.

David

-------

Wanting an affordable 9/16 tall cut-off blade. [atlas_craftsman]
Posted by: "dolphin_79605" dolphin_79605x~xxyahoo.com
Date: Wed Mar 27, 2013 2:38 pm ((PDT))

The Armstrong cut-off or parting tool holder (2020R) that came with my
lathe uses a 3/32" x 9/16" x 5" blade. I have no blade.

Searching on the net, it seems this particular size may have gone out of
favor in the last 30-40 years. I see the closest; 1/2 and 5/8 are listed
frequently. I did see one or two 9/16 on ebay, but those are crazy high.

I am wondering if anyone has uncovered an affordable source for the 9/16
size, if they changed holders or possibly are modifying the 5/8 blades to
fit as 9/16.

Being a tool that gets minimal use, maybe some one bought a stack and has
a spare. I am hoping, open and looking for ideas.

I would tend to want to stay with the holder I have, but I'd like to hear
what others are doing.

Thanks from the dry West Texas desert,
Mick

-------

Re: Wanting an affordable 9/16 tall cut-off blade.
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Wed Mar 27, 2013 3:20 pm ((PDT))

buy a 5/8 one & grind new angles on it to size it to fit your holder...
quick & easy ... less than 5 min... been there.

check victor machinery xchange for price.

best wishes
docn8as

-------

NOTE TO FILE: A conversation took place in the atlas_craftsman group in
April 2013 regarding a broken tool post slde that occurred during parting
off an overly large piece of metal. Besides ideas on replacing or
repairing the broken part, there were a number of tips on parting off.

See the following conversation in the Atlas Parts General file here.

Broke tool post slide [atlas_craftsman]
Posted by: "Dave Pinella" dpinellax~xxcinci.rr.com
Date: Sun Apr 28, 2013 11:48 am ((PDT))

-------

Progress [myfordlathes]
Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com
Date: Thu Jan 23, 2014 5:46 am ((PST))

G'day All, I'm celebrating. After 4 years in various states of
disassembly, I have finally re-assembled and run up my ML7. My wife is
struggling to share my enthusiasm, but she'll get used to it.

Now, the reason for my post. My shakedown involved parting off a 1" x
12" stainless steel bar. I just chucked it up in the 3 jaw, and lined up
a parting off tool (ground from 1/4" HSS) as close to the chuck as was
practical, set the machine on its lowest non-backgear speed and let it
go. In the process of parting off this slab of stainless, toward the end
of the process the tool grabbed a couple of times and I could see the
bar either move in the chuck, or lift the chuck. The chuck is the
original 3 jaw as-supplied circa 1948.

I have the motor belt a bit loose to give me some help if I do something
dumb and I was being pretty careful as the only time I've used a metal
lathe before was in Tech (20 years ago) to make a plumb bob.

If I just chuck up a big chunk of bar and try to move things, I don't
really feel any movement in the bearings (and that includes a pretty
hefty try). Everything seats well and runs well. A half hour un-loaded
run at the highest speed saw the countershaft get warm, but the main
bearings barely registered any heat.

What would be a sensible check (given I have a couple of dial gauges
here) to perform to check the bearing fit and alignment. I have some
bearing blue, but I've never opened the packet.

Backlash is good, I set that up when I stripped and cleaned the spindle.

Advice warmly welcomed.
Brad

-------

Re: Progress
Posted by: "Colin Johnson" csjohnsonx~xxbtinternet.com
Date: Thu Jan 23, 2014 6:17 am ((PST))

Hi Brad, This is common problem with an ML7. First, put a bar in the
chuck, put a clock gauge above the bar, grip the end of the bar and try
to lift up and down to see what play there is in the headstock bearings.
There should be no more than 0.001".

You said it ran cool, it should warm very slightly, this may suggest
excess play.

Second, minimise all play in cross slide, lock top slide and saddle.
Minimise overhang of tool and top slide. I would use a slower speed.
However, having said the above, the biggest improvement, by far, was by
using a rear tool post and inverted tool. You still need to take up all
slack.

I made my own version of G H Thomas's rear toolpost. I can now part off
at normal tool speeds. I have only once had a dig in, during the last 10
years. Thomas devotes fourteen pages to parting off in his book Model
Engineers Workshop. I don't know how much it costs now, but whatever, it
will be money well spent. I refer to it again and again.

Colin

-------

Re: Progress
Posted by: "Robert Mitchell" rmm200x~xxyahoo.com
Date: Thu Jan 23, 2014 8:34 am ((PST))

I have to add -- to part off 1 inch stainless I would use a metalworking
band saw. There is no material I dislike turning more than stainless.

Robert Mitchell

-------

Re: Progress
Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk
Date: Fri Jan 24, 2014 2:36 am ((PST))

Don't even attempt to part it off in one go!!!!!!

By that I mean spread the cut. Go in a small amount then come out go a
small amount sideways and then go in again. Repeat the process until you
are all the way through.

If you need the face of the part that has been cut off to be flat, then
try to make the final cut down that face.

If you can get away with it, use a narrow VEE shaped tool to remove the
bulk of material and again spread the cut.

Parting off is fraught with danger at the best of times. With stainless
it is worse.

With a 12" length of material support the outer end using either a steady
or a centre.

A rear mounted toolpost is a definite advantage if you have one.

If you have reverse on the machine, but no rear mounted toolpost, you may
be able to cut upside down at the front, but that would depend on the
toolpost type that you have, as you may not be able to get to the correct
centre height.

Another thought-----I would normally set the tool just below centre so as
to have the tool go away from the job, rather than pull in.

"Just another 100 year old method."

Hope this helps
Bob

-------

Re: Progress
Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com
Date: Fri Jan 24, 2014 3:28 am ((PST))

Thanks Bob. I did precisely as you suggest. Lots of in and out to clear
the chips and keep the tool cool. 2 pauses to extend and alter the grind
of the tool and about 3 pauses to re-sharpen with a diamond file. I also
cocked the tool with a feeler gauge toward the end to bring it slightly
below centre.

I got through it, but next time I'll take it next door and put it on the
band saw. Good experience however.

Picked up a new 3 phase motor today and wired up the VSD.

I know the idea is to keep the spindle below 1000 rpm, but with a standard
50HZ motor the countershaft maxes out at about 487 rpm. What are the
practical limits to the countershaft speed? 100HZ would give me 974 rpm.

I don't actually plan on going that quick, and I've programmed the VSD to
a max of 90HZ. With the link belt and the belt cover I find it exceedingly
difficult to get the belt onto the fastest setting, so I do anticipate
needing to be running in excess of 60hz from time to time.

Again, feedback warmly welcomed.
Brad

-------

Re: Progress
Posted by: "Andrew Moyes" admx~xxamoyes.fsbusiness.co.uk
Date: Fri Jan 24, 2014 4:04 am ((PST))

I wouldn't try parting off in reverse with the tool upside down on an ML7.
The chuck will unscrew.

With stainless, I think I'd use a hacksaw. Don't like the stuff!

Andrew M

-------

Re: Progress
Posted by:  lathesx~xxclockworld.co.uk
Date: Fri Jan 24, 2014 4:25 am ((PST))

It's a slight tangent, but for parting off to a reasonable accuracy, I
sometimes use an angle grinder mounted in a chop saw attachment. Using
a 0.8mm cutting disc, very little material is wasted and the blade cuts
cleanly.

I tend to use this method if I am making s/steel nuts on 1" hex bar.

-------

Re: I'm confused about tool holders [atlas_craftsman]
Posted by:  wa5cabx~xxcs.com
Date: Wed Feb 5, 2014 2:56 pm ((PST))

Not trying to convert anyone but for 10+ years I've been using ThinBit
grooving holders and cutters for parting off. I originally bought them
to cut some O-ring and Circlip grooves and found that they work well for
parting off, too.

The cutters are solid carbide and I've never needed to sharpen one.
However, the 0,062" wide ones are limited to a maximum slot depth of
around 1/2" so maximum solid diameter of 1". The 0.020" wide ones will
cut about 3/16" deep.

Robert Downs - Houston
wa5cab dot com (Web Store)   MVPA 9480

-------

Re: I'm confused about tool holders
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Wed Feb 5, 2014 4:12 pm ((PST))

> Using a cut off tool is one of the most dangerous operations performed
> on a lathe. I would use it as a last resort.

Nonsense.....  Many of us do parting off (cutoff) as a totally routine
operation. There are sensible things to do to make it go better.

1) try slower speeds.

2) Make absolutely sure that the tool is oriented parallel to the
crosslide... you do NOT want it going in "crabwise". I like to align it
with the chuck face, any decent chuck will be made square and flat across
the front.

3) keep oil on the cutter.

4) Part off only very close to the chuck. "Stickout" is the enemy.

5) Use a grind or insert type that will fold the chip, typically a cutter
with a groove down the middle, so the chip won't bunch up in a tightly
rolled wad and drag on the cut sides.

And, although this may draw the bitter ire of one of our Texas bretheren,
change AWAY from the nasty single phase motor to a smoother drive. I like
3 phase, but if you can do DC, that will also be far better. Heck, a
water wheel drive might be better.

The vibrations from the single phase torque variation will tend to start
the chatter going, and once started it generally won't stop. A cutoff
blade acts like a form tool, with a wider than usual length of edge in
contact with the work. That will start chatter in any machine that is
prone to it. And virtually any lightweight machine is prone to chatter.

Jerry

-------

Re: I'm confused about tool holders
Posted by: "Steve Metsch" stevemetschx~xxcox.net
Date: Wed Feb 5, 2014 8:51 pm ((PST))

You are all talking above a beginners head. Start with the basics.

Sharpen the cutoff tool.
Get the tool on center.
Tighten compound gibs.
Lock carriage.
Oil continuously.
Feed fast enough to keep a chip and slow enough to prevent digging in.

A new motor does not overcome bad practices.
Keep it simple.

Steve Metsch

-------

Re: I'm confused about tool holders
Posted by: "Jon Elson" elsonx~xxpico-systems.com
Date: Thu Feb 6, 2014 10:02 am ((PST))

On 02/06/2014 08:37 AM, L. Garlinghouse wrote:
> My bet is that it is a typo and the counsel is to "keep a chip" meaning
that once you start a chip flowing, keep it going, which will mean that
as the diameter decreases as you cut into your workpiece the speed of
your feed will have to keep increasing. <

No, I've watched the pros doing this, and they often use power feed, so
a constant in-feed. But, they use flood coolant to keep cutting oil
steadily flowing over the work.

I'm not brave enough to use power feed, but you want to keep a very
agressive in-feed, and I usually keep a brush applying lube in the cut.
Occasionally, I back off for a few seconds, but that would be on material
that doesn't work-harden badly.

> I have spent years getting consistantly successful using a part-off
tool on my 10" Atlas and I am not even close to occasionally successful.
So there is a lot of art and science to this little lathe task/operation.<

Yes, I rarely did deep parting-off on my 12" Craftsman. Now that I have
a 3500-Lb Sheldon 15" lathe, I find I can do it with better results. But,
you STILL have to be careful with smaller workpieces.

Parting-off produces HUGE loads on the part, and unless the cut is RIGHT
at the chuck, you may bend the part rather than part it off.

One of the other tricks I learned is to grind a "valley" on the top of
the parting-off tool. Parallel to the length of the blade, put a little
dip in the middle. This causes the chip to roll inwards as it is produced,
and therefore be narrower than the groove the tool is cutting. The chips
will curl up and make little rolls, which eventually break off and are
pushed out of the groove. You don't want these rolls to bind in the cut
when it gets deep.

Jon

-------

Re: I'm confused about tool holders
Posted by: "James Irwin" jirwin1x~xxaustin.rr.com
Date: Thu Feb 6, 2014 10:29 am ((PST))

Any slop in head bearings makes life miserable for me, but shows up worst
in parting. Therefore chatter in parting makes me check head bearing
adjustment. Then, of course, look at the total tool set-up path from chip
to ways.

Jim Irwin

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Thu Feb 6, 2014 12:53 pm ((PST))

In atlas_craftsmanx~xxyahoogroups.com, docn8as wrote:
>> cutofftool requires front & side clearance, as well as front to BACK
clearance to elliiminate binding as depth increases..a slight bit if top
rakee ground as a radius on the circumference of the wheel is of value
...finally a V ground on the face of the bit compresses the chip to
swarf by cutting the outer edges first & mitigates the jamming problem
...w/this V on the face i have been successfully experimenting w/parting
off w/ out lube on 1018 steel .....if using lantern toolpost, eliminating
the rocker assembly & replacing w/ washers or a doughnut gives stability
as good or better than a quick change & of course an openside block holder
gives ultimate rigidity ..the front to back clearance is clearly shown in
cut off tool on HS ground bits of the 1920's texts..which is where new
HSM operators shud START rather than w/ current industrial technology.
best wishes
doc <<

Feb 5, 2014 ncsailrman  wrote:
> Thanks much for that Doc. I've read that parting off can be
problematical and so will give attention to each point you make. The vee
cut idea on the face sounds like a great idea - have copied your text to
my "parting tool notes" folder.
  Like you point out, the more I learn the more it's clear why the old
school methods and info, let alone the older lathes themselves, have been
so attractive to me. I was totally fascinated upon getting a copy of South
Bend's 1942 "How To Run A Lathe" and read it cover to cover while running
up a serious sleep deficit. I even bought this copy of the old SBL ad from
WWII, flying lathes, stuck it in a dollar store frame and hung it in my
"office":
http://www.ebay.com/itm/1943-SOUTH-BEND-LATHE-WORKS-AD-FLYING-LAT
HES-of-the-AIR-CORPS-/271368572084?
  And also learning to grind HSS was definitely for me - rather than
perusing carbide tooling I invested in making a better rest for my 8"
grinder, and then later had the luck to get what was likely one of the
last of the Baldor knockoff tool grinders from Harbor Freight. It was
apparently found in the back of the store, misplaced for a year or two.
  It was $189 list back when they were still carried, but this one was
sitting on the floor, front and center, tagged as "last one, clearance,
$129". It rang up at $119 for some reason, then I had a 25% off coupon
which made it $89.25 pre-tax. These are still available at Grizzly ($354
delivered) and Enco, but even at those prices I would have just made do
with my cheap 8" grinder.
  Some have had problems with these, and I did spend a few hours cleaning
up the rest mount systems, but it works great now.
  I did learn to grind lathe tool bits freehand, but being able to set
the table angle and use a miter gauge is nice, and now with that new
accuracy capability, I'm designing a jig to do 4-facet twist bit
sharpening as most of my bits are dull and chipped. <

ncsailrman

great poster .....i knew the army had mobile machine shops, just never
considered the army air force...(became separate service after WW2).

also great coup on the baldor knock off....

remember what the " old man " said ...if you find something you really
like, better buy two cause they will either quit making it or double the
price ....been proven very true.

re drill sharpening ...while jig machine sharpened bits are more accurate
(unless one is obsessive compulsive), i wud suggest you also learn free
hand sharpening ..not difficult & just requires attention & some practice
...i touch up a bit in less than 5 seconds ...will i get as many holes as
factory grind ..NO but so what if i only get 1/4 of the # of holes ...5
sec & it is again sharp ...is it as accurate ..probably not ...so what?
how much accuracy neeeded if w/ in a couple thou, i pre drill the hole
1/64 under ..the unequal length lips no longer matter since the center is
not guiding the bit ...if i need tighter than 2 thou, bore or ream; if
you have lots of multiples of the same size, a drill jig /machine makes
good sense to me so good luck w/ your project.

FWIW machine tool operation by burghardt, any edition from 1923 - 43 vol
one & two are still by my bedside over 60 yrs later ..vol i is lathe &
bench work, soldering brazing, little black smithing; vol 2 is shaper
planer mills, grinders ...there are instructions for hand sharpening
drill bits i think in vOL 1, maybe 2..* also some videos, some better
than others...& more correct ......they shud be available for maybe $10
or so on Abe Books, Amazon, ..he was superintendant for high school
industrial training in new jersey ....very practical stuff.

the great thing abt machining in home shop is, you will never master all
there is ....life is too short....it never gets boring ..you always use
your mind ...no running off 500 parts ...that gets to be plain labor,
even tho it gains skill......doing one off jobs, keeps the mind alive &
I suspect experienced HSM may actually KNOW more than an industrial
machininst because of this, even if less skillful (skill comes from
intelligent repetition) ... particularly those who have not had a formal
apprenticeship ....professionals cannot take the time to repair or
fabricate their own tooling ...PRODUCTION is calling ...& depending on
where one is employed, they may have very limited experience after 20 yrs
on the same machine.

for years i made my own tooling ..reamers 6x48 taps /dies, slot mills,
c/bores whatever, & i had the scrap pile from those operations to prove
it ....w/out formal training i made mistakes, but i did learn ....i was
making small bore target & high power varmint rifles for the 5
competitive shooters in the family plus others, & before the advent of
cheap china tooling, the odd ball stuff was too expensive for HSM...i
still make an coccaisional metric tap when needed.

best wishes
doc
PS i shud add to the prior post that some advocate a V groove on the TOP
of the parting tool rather than on the face....i have always ground it
ON the face.

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Thu Feb 6, 2014 1:09 pm ((PST))

> The vibrations from the single phase torque variation will tend to
start the chatter going, and once started it generally won't stop. A
cutoff blade acts like a form tool, with a wider than usual length of
edge in contact with the work. That will start chatter in any machine
that is prone to it. And virtually any lightweight machine is prone
to chatter. <

a gooseneck flex tool holder will eliminate the chatter ...also great
for FORM tool cutting w/ out back gear.

w/ a very flexible one, you can watch it flex down 1/16 & back as you
PLUNGE cut w/ a 3/8 full flat point bit, & point up a one in bar ...
STRAIGHT in .......no jam ups, no chatter ......impossible w/ a solid
holder ..at the same speed .....easily made from a piece of 3/8 & 2 inch
stock ...or 1/2 X 2 inch if larger lathe ....OR ebay an armstrong one.

best wishes
doc

-------

Re: I'm confused about tool holders
Posted by: "Guenther Paul" paulguenterx~xxatt.net
Date: Thu Feb 6, 2014 1:34 pm ((PST))

The ideal way to part of  metal in your atlas is use a 1/8" wide cutoff
blade; make sure the blade is dead center of your work piece; make sure
your blade is square to the work piece. Up to 2" i run on the 1st pulley
from the chuck. if you go bigger in dia. with your work piece, run in
back gear. Keep plenty of oil on the cutter and feed slow. Nothing to it.

If you are below center the work piece will pull you in and break the
blade; if you are above center you will put excessive pressure on your
work. I have used the parting tool on long items running in the steady
rest.

GP

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Thu Feb 6, 2014 2:37 pm ((PST))

> I'm not brave enough to use power feed, but you want to keep
> a very agressive in-feed,

NEVER use power feed for cutting off on atlas /crftsmn lathes...x feed
speed is WAY too fast....not so w/ south bend /logan.

before CNC, hundreds of millions of parts were run on turret lathes, each
of these parts were parted off. it was simply another cut ...BUT these
were sturdy beasts ..& not subject to flex ..like light bench lathes &
the set up men knew their trade ......once again "crying in the
wilderness", but a gooseneck bit holder solves the problems once basic
set up is properly done.

one other thot .....use of a t/stock center will solve a lot of problems
by adding rigidity if parting off a long piece ....just make sure to back
it out well before final cut.

best wishes
doc

-------

Re: I'm confused about tool holders
Posted by:  jmartin957x~xxaol.com
Date: Thu Feb 6, 2014 3:00 pm ((PST))

Keeping the cutter cutting is important, many are too gentle with the
feed. You don't have to increase the feed rate as the diameter decreases,
though - a constant feed rate will give you a consistent chip, regardless
of diameter. What should - in theory - increase as the diameter decreases
is the spindle speed. But this is tough to do with an Atlas lathe, unless
you have a VFD controlling a three phase motor. And it's not really
necessary.

If you do increase the spindle speed, increasing the feed rate as L.H.
suggests would make sense.

One additional thing I do is to crank the compound back as far as it will
go. I keep it there, in fact, for as many turning operations as I can. It
has essentially the same effect as tightening up the compound gibs.

John

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Thu Feb 6, 2014 9:45 pm ((PST))

On 02/06/2014 Doc wrote:
>> NEVER use power feed for cutting off on atlas /crftsmn lathes...x
feed speed is WAY too fast....not so w/ south bend /logan. <<

Feb 6, 2014 Jon Elson wrote:
> Oh, yeah, the pros at our shop at work do cutoff work on a HUGE
Harrison lathe, I think it is a 20" with about a 15 foot bed. They had
the power crossfeed going at an awesome rate, too.
  Definitely can't do that on an Atlas. I think you could use the slowest
power crossfeed, and if you want, you can always throw in an extra gear
set to slow it down.  Jon <

the QC box on my crftsmn commercial has slowest speed of .042 & that is
too much for parting off for the stiffness of the lathe ...& yes the
lowest speed can be altered, but i wud not bother w;/ that for the
occasional parting off, easier to just hand feed.

my circa 1917 14 inch Monarch A at 2000 # is another story as i am sure
your sheldon, even heavier at abt 3500 # is ....last year i repaired a
logan 820 & was amazed at how SLOW the xfeed cud be run w/ out altering
the gearing to the feed box.

best wishes
doc

-------

Re: I'm confused about tool holders
Posted by: "Jon Elson" elsonx~xxpico-systems.com jmelson2
Date: Fri Feb 7, 2014 8:56 am ((PST))

On 02/06/2014 11:45 PM, Doc wrote:
> the  QC  box on my  crftsmn commercial has  slowest
> speed  of .042 & that  is  too much  for parting off  for
> the stiffnes of  the lathe

Are you SURE? I think it is .0042, which should be fine for parting off.
Maybe different on the Craftsman commercial, but the typical QC Atlas
lathe had .0042" as the finest feed, and crossfeed was equal to
longitudinal feed. I sometimes rigged an extra gear for really fine
finishes when turning.

Jon

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Fri Feb 7, 2014 9:28 am ((PST))

Jon
mea culpa......shud be .0042........aged brain again...sorry.

FWIW....12 yrs ago my 1895 Reed 14 inch arrived w/ fixed triple pulley
feeds of .007, .010, & .016... thinking not slo enuf, i made a banjo
extension, cut a couple xtra compound gears & got the feed by the
LEADSCREW, (instead of feed rod), down to .0015.....in the interim, i
used the shear grind bit for final finish cut ....all feed lines were
gone & after test i have never used the lead screw feed.......the flat
nose bit w/ front, & side & BACK clearance, set as near flat w/ abt 3
thou doc [depth of cut], does quite well also at .007 feed.

best wishes
doc

-------

Re: I'm confused about tool holders
Posted by: "Jon Elson" elsonx~xxpico-systems.com jmelson2
Date: Fri Feb 7, 2014 8:53 am ((PST))

On 02/06/2014 08:12 PM, James Irwin wrote:
> Re: [atlas_craftsman] I'm confused about tool holders [3
> Attachments]
> Ah hah!  Now I see it!  Downward pressure during cutting
> causes tool point to back away from the cut slightly and
> in proportion to the tendency to dig in. Pretty cool!

Yes, but the problem is it makes "spring" even worse. So, basically, you
are working with pressure on the tool to control depth of cut, rather than
the advance of the crossslide with the calibrated dial. So, you really
don't want to use such a tool on any cut where you want to end up at some
specific diameter. But, it should be fine for cutoff work.

Now that I have a more rigid lathe, I realize how much I was fighting
spring all the time.

Jon

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Fri Feb 7, 2014 9:10 am ((PST))

Jon, that is something that i have been wondering abt for some time,
thinking maybe the same thing ..BUT they were widely used for threading
as well a century or more back, particularly for straight in thrdng sans
a compound.

time to run some tests on 1018, which is abt all i use,
re accuracy, gooseneck vs solid tool holder.

FWIW my earlier comments abt xfeed too fast on atlas crftsmn, was in
reference to 1018......may be  adequate for softer metals ..no experience
there w/power parting.

best wishes
doc

-------

Re: I'm confused about tool holders
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Fri Feb 7, 2014 6:01 pm ((PST))

Re: [atlas_craftsman] I'm confused about tool holders [3 Attachments]
I doubt that is an issue except in theory .... The holders have been
used with good success for a long time.

1) they are not that floppy.....  just more so than the machine.

2) it was standard to put in a block, either wood, or in some cases a
metal wedge or plug, for the rough cuts. Then you take it out and do the
final cuts with the spring for better finish.

3) If you think your machine is not itself also "made of jell-O" you need
to think again. It has the same problem, but is less controlled than the
spring tool.

I fully intend to use the one I eventually make, for threading and similar
uses where the finish advantages are fully utilized.

Jerry

-------

Re: I'm confused about tool holders
Posted by: "Charles" xlch58x~xxswbell.net
Date: Fri Feb 7, 2014 6:14 pm ((PST))

If you are using a spring tool, you have to do several passes without
advancing the tool to let the spring "unwind".

Charles

-------

Re: I'm confused about tool holders [3 Attachments]
Posted by: "Scott Henion" shenionx~xxshdesigns.org
Date: Fri Feb 7, 2014 9:04 am ((PST))

On 2/7/2014 12:27 AM, Doc wrote:
> tnx Lance for posting pics ....
> in addition to the armstrong types that i have, i have
> Willard, & also Williams gooseneck threading tool holders fpr
> 5/16 & 3/4 bits ....these were used for straight in threading for
> lathes w/out compounds & also for quick coarse threads, allowing
> heavier cuts .......the first one i came upon many years ago
> was a shopmade one that held a 3/8 square bit in a shallow recess on
> the side ..the bit was captured in a squared hole in a bolt
> that passed thru & was nutted on the opposite side .....the bit
> cud be more simply held just by a a deeper slot on the side &
> grub screws on top to hold it ....
> best wishes
> doc

Tom Lipton just showed a spring tool he made:
https://www.youtube.com/watch?v=KETVR9qtEmY

I have been wanting to make one for may A/C for form tools.

I have power-fed when parting on aluminum. It can be done with steel but
it is right at the limit when parting and you don't get much time to
stop when things go wrong. ;)

Scott G. Henion, Stone Mountain, GA
Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36
Welding pages and homemade welder: http://shdesigns.org/Welding

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Fri Feb 7, 2014 9:44 am ((PST))

tnx scott, for the  video link .....great help for quick change toolpost
users ......if  making one, one can simply extend the toolnose to hold
a regular lathe bit if desired ..in addition to one for form tools.

best wishes
doc

-------

Re: I'm confused about tool holders
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Sun Feb 9, 2014 9:08 am ((PST))

think it may be the opposite ..w/ a light springy lathe, MORE force is
needed to get a cut, & there is more residual cutting effect left ...
noticeable in threading or when taking a second cut w/ out considering
the remaining cut " still " in the spring.

best wishes
doc

-------

Re: I'm confused about tool holders
Posted by: jerdalx~xxsbcglobal.net jtiers
Date: Sun Feb 9, 2014 10:25 am ((PST))

> If you are using a spring tool, you have to do several passes without
> advancing the tool to let the spring "unwind".

Actually, you do not "have to"...

You simply, as-usual, take cuts until the dimensions are correct. That's
what it is all about. The spring tool is just a way to add a spring action
that is working FOR you and not against you. A way to improve surface
finish, mostly. Hopefully Doc is wrong about your machine, and it isn't
so springy itself as to be almost useless.

Even now, you are using spring tools... the lathe is the spring. Just
because it works against you instead of for you is no reason it isn't
a spring. There is nothing magic about spring passes, or for that matter,
"sparking out" a grinder, unless you are convinced that you have dialed
in the correct cut and just need to finish it.

Many commercial machinists flat out state that they USE the machine and
tool springiness, knowing that dialing in X amount takes off Y amount,
they use that to attain the final dimension without wasting time on many
spring passes and fussing. If dialing in 20 thou actually takes off 17
thou, they can use that fact, and do.

It's all about the dimensions, and if you can get there in two cuts, or
in some cases, with a SINGLE cut, then you are good to go. I have done
cuts to take off 0.125 of material direct to final dimension. On a Logan.
You can do it on an Atlas,.

If you are being paid to get it done fast and right, "fussing" isn't in
the job description. If you can't hack it, someone else can, and they get
the job, you get the boot.

In the home shop, feel free to take however much time it takes.

Jerry

-------

[atlas618lathe]
Looking for stories about how parting off went like on your lathe
Posted by:  n1ltvx~xxyahoo.com n1ltv
Date: Fri Jun 6, 2014 8:41 am ((PDT))

I'd like to hear from anyone who's done parting off on their lathe. For
me I was just trying out the tool so I really didn't need to use it.

It was quite a while ago but this is how I think it went:
Small piece of aluminum, probably in the ballpark of 5/8 inch diameter,
most likely 6061 but I don't know for sure.

Screeching and possibly some chattering ensued so I don't think I finished
the cut. My instinct was that this kind of stress was something I didn't
want to subject the compound rest to if I didn't have to. On a bigger
lathe I'd have not been nearly so concerned.

Was using slow speed as required by parting. I have read that this is an
operation that requires aggressive infeed of the cutting tool to work well
which I sort of tried but to me it seemed like there was a considerable
risk of breaking the compound so this pretty much went nowhere with just a
pretty shallow (1/16) groove in the stock the result. I might have been
able to do it later with a pretty small piece more like 5/16 diameter.
A 7/8 inch piece of polyethylene was no problem at all.

Steel, based on my experience with aluminum, would be out of the question
for me. I would hate to snap a compound rest. In case someone is wondering
how that would break, it's usually the t slot that cracks from what I
read. I have the A-Z style (it's not actually A-Z brand) of anodized
aluminum toolholder, not lantern type.

My experience with parting off is certainly not uncommon. Here is part
of message 5072, "looking for opinions about the 618":

Q. how hard is it to use a cut-off tool on the 618, my 9x grizz was awful

A. well I did have a problem parting a 2" piece of navy brass. But that's
awful material to begin with. It escaped the chuck and hit me in the
chest!

So, what has your experience been?

Hank

-------

Re: Looking for stories about how parting off went like on your lathe
Posted by: "Jim and Judy Bevan" jbevan50x~xxhotmail.com
Date: Fri Jun 6, 2014 10:28 am ((PDT))

I part off on my 618. Many times every day. Lock your carriage down.
I also part off on the 816 many times a day making small spacers.

-------

Re: Looking for stories about how parting off went like on your lathe
Posted by:  azbrunox~xxyahoo.com azbruno
Date: Fri Jun 6, 2014 1:40 pm ((PDT))

Be sure to use an appropriate parting tool (consider width) and don't have
it hanging out of the tool holder more than it needs to.

Be sure the parting tool is sharp.

Be sure the parting tool is straight in.

Be sure the parting tool is at the correct height.

Lubricate appropriately.

Speed depends on what you're cutting. I've done slow parting and I've done
fast parting. Start with a slow infeed, just to get a feel for how well
the material is peeling. If the lathe starts dancing, back out.

While I've done a some machining of steel, I tend to stick to brass,
aluminum, rubber, plastics, etc. With steel, I work slowly.

Oh yeah, and one more thing... keep the belt loose enough so that if the
workpiece catches on the parting tool the belt will slip before the work
will rip the compound apart.

Bruno

-------

Re: Looking for stories about how parting off went like on your lathe
Posted by:  garybauer46x~xxyahoo.com
Date: Wed Jun 11, 2014 7:53 am ((PDT))

My first experience about 35 years ago with a parting tool was on my
Atlas 10x36" lathe. It worked OK on aluminum but steel was a challenge.
Fortunately I had some help from a friend and had read a bit on the
subject. The cut-off blade was held in an Armstrong c/o holder.

About 10 years later I suceeded in blowing up the lantern toolpost trying
to part a 2" diameter solid bar of steel. So I made a more rigid 4-way
toolblock and took greater care when parting thick stuff. Tricks like
cutting a double-wide slot, using lots of cutting oil, using the shortest
c/o blade extension, and setting the c/o blade square and on center
carefully helped big time.

Those lantern-rocker tool posts are for special use IMO and not rigid
enough for serious turning.

Today I have a 12x36 Atlas and a 618 Atlas lathe (plus 3 other lathes).
I'd prefer not to use the little 618 Atlas for cut-off purposes. On work
that is sized to the 618 I prefer to use a hacksaw as I do on my little
asian 7x10 lathe.

Gary

-------

Re: Looking for stories about how parting off went like on your lathe
Posted by: "Jim and Judy Bevan" jbevan50x~xxhotmail.com
Date: Wed Jun 11, 2014 8:22 am ((PDT))

I always cut off on my lathes. Tool on center, use cutting oil, use the
right speed, and on small lathes lock the carriage (saddle) down. If
anyone needs help just ask.

Thanks
Jim

-------

Re: Tool post holders [myfordlathes]
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk
Date: Thu Jul 3, 2014 10:30 am ((PDT))

otebgnx~xxjisp.net writes
>HI Just an FYI,  I have an original Dickson on my Super 7B. I recently
>neededsome new holders. The Bison ones from New England Brass fit
>perfectly out of the box.

Agreed (see my original post).

>I got a new cutoff holder also I split the original - too much muscle!

To the OP, I would strongly recommend that you don't bother with the
parting off toolholder. Get one of these:
http://www.greenwood-tools.co.uk/ishop/728/shopscr23.html

which fits the standard toolholder. I have used one for over a decade,
they are - and this is not an exaggeration - a league above the normal
blade PO tool. I used to find parting off a rather nerve-racking job,
but since buying it I now find it straightforward. I'm sure you will
find a local supplier for them, they are made by Sandvik.

David Littlewood

-------

Re: Tool post holders
Posted by: "David Everett" deverett2003x~xxyahoo.co.uk
Date: Thu Jul 3, 2014 11:43 am ((PDT))

David. The bit that goes in the toolholder can with advantage be reduced
in width to a a ball hair over 3/8" to reduce overhang. Otherwise, agree
with DL.

Dave   The Emerald Isle

-------

Re: Tool post holders
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk
Date: Thu Jul 3, 2014 5:14 pm ((PDT))

Dave, That sounds a good idea, never thought of it myself. I wonder,
indeed, whether it might be advantageous to make it a little less than
3/8", so the blade could be pressed firmly against the side of the
toolholder and reduce the (very slight) risk of vibration. Or is there
some reason that would be bad?

David Littlewood

-------

Re: Tool post holders
Posted by:  peterroachx~xxbtinternet.com x3cnc
Date: Fri Jul 4, 2014 1:02 am ((PDT))

Having used the Greenwood/Sandvik tool on the Myford, with great results,
I brought a second to fit a CNC turret. Changed the block on the side so
that projection from turret minimal. Also changed the position of the
centreline of the block, which may help on some toolholders to get
the tool tip on the job centerline.

Vibration not an issue in my experience.

Peter

-------

Re: Tool post holders
Posted by: "David Everett" deverett2003x~xxyahoo.co.uk
Date: Fri Jul 4, 2014 2:25 am ((PDT))

David. Mine is about 5 thou greater than the depth of the toolholder slot.
I just press the parting tool in tight in the holder. Never noticed any
vibration.

My thinking is that it is better to have the maximum amount of bar in the
toolholder for support -- bottom, back and top (by the screws). If the bar
is less than the depth of the toolholder slot there would be more chance
of vibration. Whichever, I believe sideways overhang is more of a problem
than vibration.

Dave   The Emerald Isle

-------

Re: Tool post holders
Posted by:  otebgnx~xxjisp.net piedrj
Date: Mon Jul 7, 2014 3:07 pm ((PDT))

Hi. I started this thread and I see it picked up on cutoff comment I made.
For what it's worth about 4 years ago a fellow model builder stopped by my
shop for the first time as he was traveling with their motor home. Even
after 35+ years I was having "fun" parting off and mentioned it to him.
He told me he almost always used power feed to part off. I was a bit
skeptical but I gave it a try, and well it worked nicely. Ever since then
I part off under power 95% of the time. The only lathe I do not use power
is the Sherline.

I use a rear parting tool and that works very well. The rear parting tool
on the Myford makes the power cutoff real smooth. I also have a  12" and
15" lathe which part off nicely under power.

Try it sometime, just clear the chips and drop some cutting fluid on it.
I just experimented with feeds, .001 works well for most everything. Try
more or less feed and soon you will have each material figured out.

Bob

-------

Re: Tool post holders
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk
Date: Tue Jul 8, 2014 11:02 am ((PDT))

Bob, You are quite right; parting off under power is more consistently
reliable. This is because with hand feeding it's hard to get an even
feed, and a slight over-enthusiastic twitch can cause a dig-in, usually
with disastrous consequences. I always use pxf if I have it (on my M300,
but my S7 doesn't have it). With the Q-cut, there is also no advantage
in using a rear position, which makes life a lot simpler.

David

-------

Rear toolpost? [myfordlathes]
Posted by:  hoonerbobx~xxyahoo.com
Date: Fri Aug 22, 2014 1:36 pm ((PDT))

Hello all,I'm thinking of purchasing a rear tool post for parting off.
I see that both Chronos and RDG have similar offerings and am wondering
if anyone can recommend either?

Thanks
Rob

-------

Re: Rear toolpost?
Posted by:  ejandptrx~xxbtinternet.com philandjorobbo
Date: Fri Aug 22, 2014 2:30 pm ((PDT))

Which type of rear post are you thinking of, the simple one or the
Quick-change type? I once bought a QC type from RDG and it was not
accurately made, nor properly hardened. May have improved since then
of course.

Phil   Lancs UK

-------

Re: Rear toolpost?
Posted by: "Cliff Coggin" clifford.cogginx~xxvirgin.net
Date: Sat Aug 23, 2014 1:20 am ((PDT))

And pigs might fly.

Cliff Coggin   Kent  England

-------

Re: Rear toolpost?
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood
Date: Fri Aug 22, 2014 4:34 pm ((PDT))

I have a rear toolpost (not one of the above) and it's fairly worthless.
Not that it doesn't work, it's just pointless. If your cross slide ways
are properly adjusted, the spindle bearings are OK and you use a decent
tool, you should have no trouble parting off from the front. This:

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

is the best parting tool I have used (and I tried quite a few before
buying it!). I have seen Myford (I mean the real Myford before it went
out of business) demonstrators parting off under power with complete
ease; I can't do this on my Super 7 (no PXF) but I also have a bigger
version and use this to part off under power on my larger lathe with no
problems. Just make sure you get the tool exactly perpendicular to the
work, and lock the saddle - if you haven't yet, fit one of these:

http://www.hemingwaykits.com/acatalog/Saddle_Lock_Handle___Myford_Lathes.
html

Parting off under power can actually be an advantage, as you get a
perfectly even feed; uneven feeding is a major cause of dig-ins. If you
are doing it by hand, try to keep the feed very even (whether using
front or rear tool, you can still get a dig-in if you are hamfisted).

You will no doubt hear plenty of contrary views - but I bet very, very
few of them are from those who have actually used a Q-cut.

David Littlewood

-------

Re: Rear toolpost?
Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7
Date: Fri Aug 22, 2014 11:21 pm ((PDT))

I wouldn't call it "worthless"; a rear toolpost provides another place to
keep a second tool immediately available and aligned. For example, when
making a number of spacers with a particular length, I use one tool in the
front toolpost to face/chamfer and then cutoff using the rear toolpost. By
adjusting the topslide to set the offset between front and rear toolposts
I can just move the cross slide back and forth to automatically cut the
pieces to the correct length.

-------

Re: Rear toolpost?
Posted by:  hoonerbobx~xxyahoo.com
Date: Sat Aug 23, 2014 1:39 pm ((PDT))

I don't have any particular problems with parting off, but having a
long cross slide I was tempted by the convenience of a rear toolpost
with a semi permanent parting tool. I've not used RDG for some time,
after having "issues" which were resolved, and was wondering if their
quality control had improved.

Rob

-------

Re: Rear toolpost?
Posted by:  csjohnsonx~xxbtinternet.com
Date: Sun Aug 24, 2014 11:32 am ((PDT))

Hi Rob, I made one based on G H Thomas’s Design. The lower part of the
body was cast in aluminium. It works very well. When I made it I only had
a short cross slide. So I used only the last slot and had the end hook
over the cross slide and was secured by a 1/4” bolt tapped into the rear
face of the slide. Now never have any problem parting off.

Colin

-------

Issues with making small brass spacers [[SherlineCNC]
Posted by:  kaericksonx~xxearthlink.net kerickson
Date: Sun Nov 2, 2014 8:38 am ((PST))

I needed to some small brass spacers (0.125" OD x 0.008" long). I used
the Sherline parting tool and mounted the brass tube in a 4 jaw self
centering chuck. When the parting tool finished cutting I was left with
a small piece of material at the end of the spacer where the parting tool
didn't remove the material. I had to mount the small spacer in the chuck
and use a cutting tool to remove the unwanted material. I tried different
cutting angles with the parting tool (center, left of center and right of
center - all with the tip of the parting tool at the center line). Nothing
changed. I even tried with 0,400" dia tubing which had the same results.

Any suggestions as to what I might be doing wrong or is this the expected
behavior?

FYI, I found out the hard way that those little pieces of brass tubing
would fly off lathe when the parting tool cut through the tube. Problem
solved when I placed a 1/16" dia rod inside the tube. When the parting
tool finished cutting the tube the cut piece would slide off on to the
rod and not into outer space.

TIA,
Ken

-------

Re: Issues with making small brass spacers
Posted by:  kaericksonx~xxearthlink.net kerickson
Date: Sun Nov 2, 2014 8:44 am ((PST))

I mis-stated the size of the spacer, it should be 0.125 dia x 0.080" in
width. Also the size of the extra material at the end where the parting
tool cut was equal to the width of the parting tool.

-------

Re: Issues with making small brass spacers
Posted by: "Ken Condal" kencondalx~xxyahoo.com kencondal
Date: Sun Nov 2, 2014 9:16 am ((PST))

The standard Sherline parting tool has a zero degree lead angle, which
means the cutting edge is exactly parallel to the piece you’re cutting.
This always leaves a nub (at least it does for me).

If you have the tools and skill to sharpen your own tools (I don’t) you
can change the lead angle to 7 degrees so that it cuts the part free
first (without a nub) and then completes the cut on the waste piece.

What I’ve done is buy tooling from ThinBit. It’s not cheap and you’ll need
to buy one of their holders, but the bits are carbide, they’re insanely
sharp and they solve the problem.

Ken

-------

Re: Issues with making small brass spacers
Posted by:  kaericksonx~xxearthlink.net kerickson
Date: Sun Nov 2, 2014 9:31 am ((PST))

Ken, Thanks for the info. I've heard of ThinBit before but haven't bought
anything from them. I guess I should explore them now.

Thanks,
Ken

-------

Re: Issues with making small brass spacers
Posted by: "Alan Marconett" KM6VVx~xxSBCglobal.net km6vv
Date: Sun Nov 2, 2014 10:29 am ((PST))

Punch them out of shim stock?

Alan

-------

Re: Issues with making small brass spacers
Posted by: "JB" jambomacx~xxsbcglobal.net jamboacn
Date: Sun Nov 2, 2014 10:35 am ((PST))

Might try jamming a candle or some plastic rod inside the tube before
parting, approximating a sacrificial backer. If you can wrap the 1/16"
rod in double sided tape, that might work too… the trick is to get
something inside the tube which will keep the spacer in place for the
last few turns to ensure the nub is actually cut.

John B.

-------

Re: Issues with making small brass spacers
Posted by:  kaericksonx~xxearthlink.net kerickson
Date: Sun Nov 2, 2014 12:33 pm ((PST))

I could have tried that - if I had the shim stock to begin with. As it so
happened I had a 1/8" dia rod which fit inside the hole that I was trying
to space out. On top of that I don't have a hole punch that small, plus
I would to drill all centers to fit the 1/16" rod that passed through
the hole.

-------

Re: Issues with making small brass spacers
Posted by:  kaericksonx~xxearthlink.net kerickson
Date: Sun Nov 2, 2014 12:45 pm ((PST))

I think it would be difficult to get something small enough to fit inside
the 1/8" tube to hold the two pieces together long enough to cut clean
through without leaving a nub behind.

I think the ThinBit tool that someone pointed out would also do the job
with a leading 7 degree cut instead of the 0 degree cutting tip that the
Sherline tool has.

As it is now, I just chucked up the small piece with the nub side facing
out so that I could cut it off by turning it with a cutting tool. A little
bit of a pain but I did 24 pieces in under 30 minutes with all having a
finished length of 0.080" +/- 0.015". Close enough for government work. ;)

Ken

-------

Re: Issues with making small brass spacers
Posted by:  jowhowhox~xxyahoo.com jowhowho
Date: Sun Nov 2, 2014 3:47 pm ((PST))

Grind the end of the cutoff bit so the right corner protrudes a lot, with
an acute (45 or so) angle -- no radius.

Remember brass is grabby and should be cut with negative or zero rake
angle -- grind the top flat at the very tip.

Grinding a 1/4" bit for this task would probably be more efficient than
mutilating a cutoff tool.

-------

Re: Issues with making small brass spacers
Posted by: "Stan Stocker" skstockerx~xxcomcast.net stanstocker
Date: Sun Nov 2, 2014 3:56 pm ((PST))

A thin wire in the tailstock chuck will also catch the cut off spacers,
and can be bent down so they drop out of the way.

If you can rig it up, and Xacto blade with a flat upper surface can be
used for very fine cut off work. You'll still have some burr on cut
off pieces, but it will be minimal and easily removed with a small
countersink.

Have fun,
Stan

-------

Re: Issues with making small brass spacers
Posted by:  lenshermanx~xxyahoo.com appsmangler
Date: Mon Nov 3, 2014 11:34 pm ((PST))

The trick to a clean edge when parting off is to slightly angle the grind
of the top of the parting tool such that the side facing the cut off
piece is a bit longer so it cuts though first.

OTOH, this gives you a more ragged edge on the part still in the chuck,
but that can be faced before cutting the next piece.

-------

Cutoff tool problem [atlas_craftsman]
Posted by:  kbx~xxmuziker.org kbjorling
Date: Sat Nov 15, 2014 11:53 am ((PST))

As a largely self-taught lathe operator I've occasionally surprised myself
with good results and I've figured out solutions to troublesome problems.
But one operation continues to frustrate me: Cutoffs!

I've used:
a) a standard cutoff blade mounted in the standard holder in the lantern
    post,
b) a standard cutoff blade in a quick-change tool post (admittedly a
    rather low-grade budget QCTP, but one which I got to know and which
    I was able to use well for other operations),
c) a hand-ground tool, ground to a narrow, straight tip.

Whatever I use, I get lots of chatter &/or a pronounced tendency to hog
in, sometimes displacing the work and/or the tool. All this on steel,
aluminum, and brass.

I've had the best luck with brass, but I think that's just because it's
generally easy to work with - or so I find.

Has somebody somewhere written down the secrets of shaping and positioning
cutoff tools, or has anyone found a decidedly better tool or mounting?

As before, if you know of a document in the collected files here and can
just direct me to it, rather than writing everything out, please do so,
with my thanks!

Kurt B.

-------

Re: Cutoff tool problem
Posted by: "Scott Henion" shenionx~xxshdesigns.org shdesigns2003
Date: Sat Nov 15, 2014 12:15 pm ((PST))

I have no problems with my QCTP holder. I no longer have a lantern post
so can't help there.

Some tips:

1. Use a minimum stickout from holder and don't have holder far off the
    side of toolpost.
2. T or P blades work best (have side clearance).
3. Hone the end after grinding (I use a wet stone).
4. I find higher RPM works best.
5. Lots of cutting oil.
6. Lock carriage.
8. 1/16 blades chatter easily. 3/32 is far stiffer. I use it on
    anything over 1".
9. Make sure spindle bearings have no play.
10. Remove any slop from cross and compound slides (I keep my compound
     real tight as I rarely use it.)
11. Use a smooth consistent feed. Don't back off and allow the blade to
     chatter.
12. Replacing my feed nut helped. I had lots of play.
13. Cut as close as possible to chuck and use a tailstock center (loosen
     as you approach the center.)
14. Make sure tool is exactly on center when cutting all the way
     through. Slightly above center can help work climbing but will
     only cut so far.
15. The relief angle effects how easy it digs in.
16. I have ground  additional back rake in tools. Makes cutting easier.

#3 made big difference on how easy the tool cuts.

Scott G. Henion, Stone Mountain, GA
Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36
Welding pages and homemade welder: http://shdesigns.org/Welding

-------

Re: Cutoff tool problem
Posted by: "Carvel Webb" carvelwx~xxabsamail.co.za cwlathes
Date: Sat Nov 15, 2014 12:17 pm ((PST))

Kurt,
The collective wisdom of the group would possibly comprise a book on
this topic , but one or two things to consider are:

- Tighten up the gibs on the cross slide and top slide for the parting
    off operation.
- Make sure the tool is exactly at centre height.
- Use a slow speed and plenty of coolant.

Alternatively you might try the Myford approach of a rear mounted tool
post with an upside down tool. This has the effect of lifting the cutting
tip away from the work if it hogs in rather than jamming up.

Atlas had a cut off attachment for this, for turret type operations and
they still pop up occasionally.

Or you can get one of the after-market slotted cross slides like the
Myford type for mounting the rear tool post permanently.

The slotted cross slide is also useful for holding work pieces for
between centre boring or other milling type operations.

If your chuck is mounted securely, you can use the same approach from
the front by turning the tool upside down and running the lathe
backwards.

But parting off on a light lathe remains a delicate issue,

Carvel

-------

Re: Cutoff tool problem
Posted by: "Lance Eggleston" gbofx~xxverizon.net crashbone256
Date: Sat Nov 15, 2014 1:29 pm ((PST))

I have found that you need lube and a way for the chips to get out.

I grind a relief on both edges so the cutting tip is widest, tapers back.

For AL, WD40 lube or kero works well.
For steel, ENCO #1 or neutragena clear face soap works well.

Also, if you have a spring tool holder, that reduces most all of the
chatter.

lance

-------

Re: Cutoff tool problem
Posted by: "Doc" n8as1x~xxaol.com docn8as
Date: Sat Nov 15, 2014 2:25 pm ((PST))

second what lance wrote & go some further ...w/ edge of grinder, cut in
a V on the vertical face ...this  collapses the chip to near powder &
stops jamups ..ALSO start out at 1/2 the  cutting  speed  on the  atlas/
crftsmn to see what speed you need.....one more thing using lantern tool
post turn the large washer upside down & shim to correct center ....way
more rigid.

YES a gooseneck (spring) toolholder solves nearly all problems.

best wishes
doc

PS w/ the bit ground as lance said & w/ a V in face, i have been cutting
off 1/2 or so 1018 w/out lube .... using spring tool ...not recommending
but still testing. i have near dust, not chips, & it clears.

one other thought ....if your jaws are bell mouthed (worn on end & not
holding there ON END), it will drive you crazy trying to part off.

-------

Re: Cutoff tool problem
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Sat Nov 15, 2014 3:11 pm ((PST))

The advice given is good. I cut off with whatever I have handy that
is narrow, or I use an insert cutoff tool. Works fine. It SHOULD be
relatively routine, it's not an unusual task. I've been using a thin
HSS ground cutter, about 0.040, for small stuff for a while, I've been
leaving it in the 4 way handy for use.

So, do the stuff mentioned, although I do NOT find that being on-center
is a big deal. All that happens if you are NOT, is that you tend to leave
a "stem" uncut, and so your part does not fall off cleanly.

The most important thing you can do, besides losing the lantern post, and
getting real close to the chuck or collet, is to get the cutoff tool dead
perfect at 90 degrees to the spindle axis. Line it up against the front of
the chuck, that's a good way, any decent chuck will be dead flat on front.

Faster can be good, but slower is OK also. Chatter is going to happen, so
when it does, get some cutting oil on the cut, and change speed or feed
to get rid of it. Usually nibbling at the cut chatters worse, so try a
little more feed. I'd not try more RPM right away, that just puts more
tool-breaking energy into the system. You can get into that later when you
begin to "feel your oats" about cutoff being easy, then you'll "get it".

If you get stupid crazy screaming chatter, well, about the only thing left
is to go 3 phase. That makes everything work just like the textbooks say.
Single phase power adds a 120Hz chatter frequency that you cannot get rid
of at all. With single phase, and some machines, you will never get rid of
crazy chatter. I had 10X more trouble until I changed to 3 phase.

A spring toolholder may also be good, I have never used one, although I
have intended to make one for a long time. Just haven't got round to it
yet.

Jerry

-------

Re: Cutoff tool problem
Posted by: "Jon Elson" elsonx~xxpico-systems.com jmelson2
Date: Sat Nov 15, 2014 5:03 pm ((PST))

Yup, a classic problem. Parting-off is a high load operation, and any
looseness in the lathe makes it far worse. You have to have the site
being cut close to the face of the chuck, and the extension of the cutoff
blade just far enough to reach the center of the work. You want to avoid
having the compound rest leaning out toward the spindle. Have the slide
of the compound well-centered over the base/swivel part.

This tool overhang is what causes the hogging in. The downward force on
the tool leans the stack of saddle/cross slide/compound/tool post in
toward the spindle, making the cut deeper.

Forget the lantern post, the rocker can slip. The old pros tell you to
remove the rocker and place cutting bits there to bring the tool to the
right height.

A good QC post can give a much more secure base. I have a cutoff tool
holder for my QC post, but the blades come with a flat top. I grind a
valley down the middle of the top. This causes the chips to fold inward
slightly, preventing them from binding in the groove as you cut off.

Finally, you have to keep up a steady aggressive feed, and use LOTS of
cutting lube to keep the chips from jamming in the cut.

Jon

-------

Re: Cutoff tool problem
Posted by: "brokenwrench1 ." brokenwrenchx~xxgmail.com
Date: Sat Nov 15, 2014 5:05 pm ((PST))

ok here are some things to look for:
1. lock the saddle when making the cut
2. check the gib keys on cross feed and  compound feed for too loose fit
3. do not have compound extended toward work
4. the machinery handbook has a section showing how to grind the cuttoff
    blade
5. when grinding a cutoff blade i sharpen the end with about a 3 degree
    point with long side next to chuck
6. i grind a chip breaker on the tip of the blade
7. when using a lantern post i do not level the cutoff blade; i angle it
    up slightly and then center the the cutoff blade slightly higher than
    with the tip if the dead center. this will help compensate for the
    blade dipping in a cut due to wear in the machine.

i hope this helps. this was the procedure taught in MATC 2 yr tool and
die maker AAS degree. i had to make parts on some very worn NAVY surplus
lathes in the 1st year lab; the new ones were in the second year lab.

------

Re: Cutoff tool problem
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Sat Nov 15, 2014 9:10 pm ((PST))

There are a lot of suggestions being thrown around.

In case these are all thought of as absolute "must-do" stuff, here's a
varied collection of tools I have fairly recently used to cut off stock
and parts of various types and sizes. Most of the variety is caused by
using the first tool I came to that looked like it would work... and that
would fit in the holder I had on the machine, etc.

http://smg.photobucket.com/user/jstanley/media/tooling/cutoff
tools2_zps9e059057.jpg.html

All of them have worked fine many times. Some of them violate several
"rules" about making a cutoff tool.

Alignment, tightness, work position, appropriate speed, and appropriate
feed (I usually feed by hand) are much more important than perfect grind
of the tool.

Jerry

-------

Re: Cutoff tool problem
Posted by: "Steve w" stevewatrx~xxhotmail.com stevewatr
Date: Sun Nov 16, 2014 6:23 am ((PST))

I've read every one of the replies. Lots of good info. I just wanted to
add one tip I did not see mentioned yet.

When cutting off a large diameter, as the slot deepens, chips may not be
able to escape, and can cause problems. To avoid this, at the halfway
point, retract the blade fully, move it to the right a smudge, then widen
your first cut. Then return the cutter position to the left side of the
slot, and finish the cut. The wider outer slot gives extra clearance to
the sides of the blade.

Hope this makes sense. Hard to put into words what I mean.

Steve W. 		

-------

Re: Cutoff tool problem
Posted by: "Carvel Webb" carvelwx~xxabsamail.co.za cwlathes
Date: Sun Nov 16, 2014 9:14 am ((PST))

Steve - makes perfect sense, thanks

Carvel

-------

Re: Cutoff tool problem
Posted by: "Paul DeLisle" ferretpdx~xxgmail.com judytv_75709
Date: Sun Nov 16, 2014 8:30 am ((PST))

Okay, guys... I fully admit that I'm a tyro at all this (one High school
shop class *mumble* decades ago, and some talks with my Tool-maker Dad
when he was still around). But for most applications, I have *NEVER*
understood the whole Parting-tool thing.

I regularly (and carefully) use a fine-bladed hacksaw, with a large, round
handle (to protect against possible kickback)...it's a lot quicker, wastes
less material and sure, you might need to dress the "finished" surface a
bit, either on the lathe, or with Emery paper on a Surface Plate. But
that still takes less time (IMO) than changing tools to a Cutoff bit,
especially when you consider *all* of the issues that have been discussed
for the last several days.

Someone please.tell me why I'm wrong?

Paul DeLisle

-------

Re: Cutoff tool problem
Posted by: "Scott Henion" shenionx~xxshdesigns.org shdesigns2003
Date: Sun Nov 16, 2014 8:36 am ((PST))

I can part off far faster than using a hack saw. A saw is fine for small
stuff (less than 1/2") but bigger stuff it is much faster. Setting up my
cutoff tool takes less than 5 seconds with a QCTP.

I have done some 3" stock. Part down about 1/2" then put it in the metal
band saw.

Scott G. Henion, Stone Mountain, GA
Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36
Welding pages and homemade welder: http://shdesigns.org/Welding

-------

Re: Cutoff tool problem
Posted by: "Glenn N" glennsneffx~xxgmail.com sleykin
Date: Sun Nov 16, 2014 9:04 am ((PST))

> Someone please.tell me why I'm wrong?

Ok :)  I was right there where you are about 6-8 years ago. Then I
decided to figure out how to make it work. I have an AXA size QCTP and
cobalt "T" shaped parting tools. I grind a dovetail tool profile (notch
the face) and spin the lathe as fast or faster than I would with a
regular indexible carbide bit. I lock everything that isn't going to move
and I am not timid with the infeed. Granted I broke a couple $15 parting
tools getting the hang of it.

There are still some scrapyard steel pieces I have a little trouble with,
but if I can get a nice finish with regular turning/facing tools I can
part it off nicely. I do use lots of cutting lube. (I use ATF and an acid
brush...the kind with the hollow handle that fills with the oil and leaks
out slowly.)

I have several old carbide tipped circular saws I am thinking of cutting
up to make parting tools with. I don't know how well the carbide in the
woodsaw blades will hold up but it is free to try, LOL.

Glenn

-------

Re: Cutoff tool problem
Posted by:  wa5cabx~xxcs.com wa5cab
Date: Sun Nov 16, 2014 10:00 am ((PST))

For both grooving and parting off up to about 3/4" dia. or for hollow
parts and tubing, I have for years used a product called "THINBIT made
by Kaiser Tool Co. in Ft Wayne, IN. They make a several lengths and over
100 widths from .004" up to .250" but I have been mostly using two
cutters that are .062" wide with cutting depths of about 1/4" and about
1/2". I also keep a few short .029" ones for making circlip grooves.

And they make an ID grooving version but I've never used it. The cutters
are held in a square bar similar to any other replacable insert holder
(except that the cutter mounts on the side). I've forgotten what other
holder sizes they sell. I use the 3/8" square ones. Cutters available in
two or three carbide grades and M2 HSS.

Robert Downs - Houston
wa5cab dot com (Web Store)   MVPA 9480

-------

Re: Cutoff tool problem
Posted by: "Curt Wuollet" wideopen1x~xxcharter.net curt.wuollet
Date: Sun Nov 16, 2014 1:03 pm ((PST))

I have to second the insert tools. At work, even on a LeBlond, cutting
off wasn't 100% especially on soft aluminum and often the ends needed
cleaning up. For a job I had to make a lot of spacer buttons and the
parting tool wanted to collect aluminum unless flooded. To avoid the
mess I opened the MSC catalog and ordered an insert cutoff tool and a
single point threading tool and inserts.

It looked spindly and I thought it would fold or lose inserts which were
only clamped with a thin arm. But, I put it in a tool holder and set it
to centerline, then parted off about 50 buttons without incident at the
much higher speed recommended. I don't remember who made it, and it
wasn't in the hobbyist price bracket, but I looked it over very carefully
and it must be magic. It would be cheap if you had to do that all day
every day. At least 5 times more production.

-------

Re: Cutoff tool problem
Posted by: "Charlie Gallo" Charliex~xxTheGallos.com charlie11364
Date: Sun Nov 16, 2014 10:38 am ((PST))

On 11/16/2014 jerdalx~xxsbcglobal.net wrote:
> There are a lot of suggestions being thrown around. 

Read this by the late Teenut (aka Robert Bastow)
http://yarchive.net/metal/parting_off.html

Charlie
www.baysidephoto.com   www.thegallos.com

-------

Re: Cutoff tool problem
Posted by: "Charlie Gallo" Charliex~xxTheGallos.com charlie11364
Date: Sun Nov 16, 2014 10:50 am ((PST))

On 11/16/2014 Steve w stevewatrx~xxhotmail.com wrote:
> I just wanted to add one tip I did not see mentioned yet. When
> cutting off a large diameter, as the slot deepens, chips may not be
> able to escape, and can cause problems. To avoid this, at the
> halfway point, retract the blade fully, move it to the right a
> smudge, then widen your first cut.

Or just shape the top of your cutoff blade like a V (doesn't have to
be much), it causes the chip to fold to be narrower than the slot.

Everyone says slow down. Why? Seriously? It is a cutting operation,
and if you slow down, you tend to over feed the cut particularly as
you get closer to center.

Read the Teenut link I posted. I regularly part off at full speed,
and I'm talking full speed for CARBIDE, aka my lathe rarely is spinning
below 800 RPM. Yes, I use a QC toolpost, and I even use carbide insert
parting tools (with the pre-ground chip curling built in).

I regularly part 1.5" 4140, 2" brass, 2.5" 6061 etc. Those are EASY,
try parting 3/16" aluminum, brass, etc. -- there, the WORK wants to bend
unless you are RIGHT against the collet/chuck, and you often need to
go to HSS for a SHARP edge for parting.

Charlie
www.baysidephoto.com   www.thegallos.com

-------

Re: Cutoff tool problem
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Sun Nov 16, 2014 1:48 pm ((PST))

And?

I have violated every one of the rules even his rules, at various times,
and had success. Not generally two at a time, but sometimes.

If you have the tool square to the work, and things tight enough that you
don't get screaming jumping chatter (common with single phase) you should
get the part cut off.

Some machines are too loose to do a good job with single phase power. OK.
Don't do that.

But parting off reasonable sized workpieces does not need to be a problem.
You want to part off a 6" round on a 10" lathe? Well, then there may be
an issue.

Jerry

-------

Re: Cutoff tool problem
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Sun Nov 16, 2014 2:01 pm ((PST))

> Everyone says slow down.  Why?  Seriously?

Why slow down?

Because it may work better, that's why. I often see that slower REDUCES
chatter, as does increased feed. Nibbling and rubbing makes chatter too,
directly or indirectly. At slower speeds, a slightly faster feed is
easier, the machine has the torque. At higher RPM, the machine may not
have the torque to pull anything but a nibble.

Speeding up adds a lot of energy to the problem, and very often bad things
happen, if conditions are correct for them. Instead of a stall, things
break. Stuff happens before you know it happened. When you get used to how
cutting off works, then push the limits, sure. But I would NOT suggest
someone put the machine on max RPM and try cutting off.

You do not know WHAT they are cutting off, you don't know if the SFM will
be appropriate. Just about anything that works faster, works slower as
well*. But quite a few things that work slower don't work at ALL going
faster.

So YES go slower, maybe a couple hundred RPM, and feed appropriately. Just
because someone "might" overfeed, is no reason to have them set RPM to
max.....  The near-center feed vs RPM thing is true at any speed.

Slower gives time to see what and how stuff is happening. Good experience.
And unless you are in a production shop, it's no problem as far as output
is concerned.

* OK, carbide does not give the nice negative rake finish at slower
speeds... too bad, the machine probably won't spin the part that fast
and take a deep enough cut anyhow.

Jerry

-------

Re: Cutoff tool problem
Posted by: "Charlie Gallo" Charliex~xxTheGallos.com charlie11364
Date: Sun Nov 16, 2014 2:55 pm ((PST))


On 11/16/2014 jerdalx~xxsbcglobal.net wrote:
> * OK, carbide does not give the nice negative rake finish at slower
> speeds... too bad, he machine probably won't spin the part that fast
> and take a deep enough cut anyhow.

Jerry, I have NEVER used negative rake carbide, and honestly, even in
industry, except for extreme roughing, I understand they are almost
totally obsolete! It  isn't 30 years ago (or even 20). Today, even
negative rake holders are usually used with inserts that have a molded
chip breaker that makes them have a positive rake cutting edge, and
many many types (CCMT etc) are USUALLY positive, and sometimes HIGHLY
positive rake. The change came about as carbides got tougher, and
tough to the point they can make the sharp edge needed for a positive
rake, and not break

An example for aluminum:
http://www.iscar.com/eCatalog/Family.aspx?fnum=919&mapp=IS&ap
p=30&GFSTYP=M&cat=3602210

for steel
http://www.iscar.com/eCatalog/Family.aspx?fnum=1434&mapp=IS&ap
p=30&GFSTYP=M&cat=3602210

The chip breaker gives you positive geometry.

Most folks part off too slow, and half the problem is they thing they
need to be in lowest back gear. I'm NOT saying you have to be up at
800 or 1100 rpm like I tend to run, but I'll tell you even running HSS
parting blades (T top cobalt or not), I've had a LOT better luck even
with a straight armstrong holder (which we used up in the old shop
where I mentor) not even thinking about back gear. A few hundred RPM
is fine.

Now, if you have one of those crazy angle offset armstrong holders (I
have one around somewhere - came with my lathe) good luck, because
then you are not only fighting down pressure, but twist.

Charlie
www.baysidephoto.com   www.thegallos.com

-------

Re: Cutoff tool problem
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Sun Nov 16, 2014 3:11 pm ((PST))

Oh, when I say slower, I mean a couple hundred RPM, unless that is too
much SFM for the cutter.

Using backgear is flat crazy....

Jerry

-------

Re: Cutoff tool problem
Posted by: "Charlie Gallo" Charliex~xxTheGallos.com charlie11364
Date: Sun Nov 16, 2014 3:56 pm ((PST))

> Using backgear is flat crazy....   Jerry

Oh, then we agree. I've seen way too many people say that to part off
you need to be in back gear, and in fact, lowest back gear. That's
just TOO slow.

I've found that my 3990 (aka commercial Atlas) can be pushed a LOT
further than most folks think. I do some commercial jobs on it, and
have the turret tailstock, and a QC tool post, and I push the lathe at
1100 RPM so often it's scary. I used to run the 3AT lever collet
closer a lot, but got a spindle nose mount lever 5C close about a year
ago, and I fly with that. Allows me the full 3/4" through and it is
rare material that needs to run slower than 1100 RPM at 3/4". Let's
face it, that is ONLY 216 SFM, and even 316 stainless isn't a problem
at that speed (again, positive rake carbide). Yes, I'll drop down a
speed or two on .75" 6Al4V titanium, but 1/2"? I'll stay at 1100rpm
(and yes, I turn Titanium on the atlas, I find it TURNS like 316L, but
drilling is 'interesting' as it seems to 'grab' the drill bit, so
you'd better keep it lubed)

Charlie
www.baysidephoto.com   www.thegallos.com

-------

Cut-Off Tool Problem
Posted by:  lhghousex~xxsuddenlink.net garlinghouseles
Date: Sun Nov 16, 2014 6:56 pm ((PST))

Thanks to the group I've had more success in the last several years
parting off than the ever before.

The first big breakthrough for me was the QCTP [import, cheap but an
improvement].

BUT the really big thing [and I've not seen it mentioned in this
discussion yet] was LOCKING DOWN THE CARRIAGE before you start your cut.

As they day, the Devil is in the details, especially on a light lathe.

L8r,
L.H. in the chilly southern Ozarks of the SE USA

-------

Re: Cut-Off Tool Problem
Posted by:  wa5cabx~xxcs.com wa5cab
Date: Sun Nov 16, 2014 11:00 pm ((PST))

Anyone who does any facing or parting off operation without first locking
down the carriage is asking for trouble to begin with. All you've got to
do if you don't is bump the carriage feed handwheel and you'll ruin or
break something. #1 rule for almost any operation involving moving either
the cross slide or the compound is to first lock the carriage.

Robert Downs - Houston
wa5cab dot com (Web Store)   MVPA 9480

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Re: Cut-Off Tool Problem
Posted by: "jo barden" jobarden422x~xxmsn.com jo_brdn
Date: Sun Nov 16, 2014 11:20 pm ((PST))

I am afraid I cheat. I use my bandsaw and just face off in the lathe.
I do have parting tools and do sometimes go back and have a try but as
I say if I want to cut at a point the bandsaw is my go to tool.

Jon

-------

Re: Cut-Off Tool Problem
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Mon Nov 17, 2014 5:15 am ((PST))

You do not even need to bump anything. The cutting forces alone can move
the carriage enough to cause trouble, especially with a very lightweight
machine and carriage such as the Atlas. You might get away with it on a
13" Southbend, where the carriage weighs nearly as much as the entire
Atlas lathe.

Facing also requires locking the carriage, or you will get some strange
shape as the resulting surface. It's a good idea to lock the carriage
when an operation does not use the turning feed, such as facing, cutting
off, using a milling attachment, cutting grooves, etc.

Jerry

-------

Re: Cut-Off Tool Problem
Posted by: "jo barden" jobarden422x~xxmsn.com jo_brdn
Date: Mon Nov 17, 2014 10:16 am ((PST))

On 11/17/2014, Whit WhitPUSMCx~xxaol.com wrote:
> Mind telling me which bandsaw!?

Hi Whit, I have a Chester H80
http://www.chesterhobbystore.com/h80-bandsaw-4098-p.asp
not the best in the world but does the job. Also use use cheap pond
pump to pump cutting fluid which makes the blades last longer.

Jon

-------

Re: Cut-Off Tool Problem
Posted by: "Jon Elson" elsonx~xxpico-systems.com jmelson2
Date: Mon Nov 17, 2014 11:09 am ((PST))

On 11/17/2014, Whit WhitPUSMCx~xxaol.com wrote:
> Mind telling me which bandsaw!?

I've got one of those hideous 4x6" horizontal/vertical bandsaws. But,
it makes quick work of slicing up various materials. Leaves a ragged
edge, but then you can face, etc. as needed. Sometimes there is a real
need to part off on the lathe, after finishing a part on the chuck.
But, when you don't have to, it may just be easier to cut the stock first
by sawing.

I now have a 15" Sheldon lathe that makes parting-off easier, due to
massive rigidity, but I still only do those jobs that really need parting
off. I have shattered a few T-style cutoff blades.

Jon

-------

Re: Cut-Off Tool Problem
Posted by: "Carl Hollopeter" chollox~xxbellsouth.net
Date: Mon Nov 17, 2014 11:49 am ((PST))

If you have a QCTP, here are some part #s for the cut-off tool I use that
works quite well: SHARS Tools (www.shars.com) Part #s 404-0402 Blade
holder, # 404-0379 Blade for inserts. Inserts from Enco (www.use-enco.com)
Part #s 359-3025 Carbide Insert, # 359-3026  Carbide Insert TiC/TiCN/TiN
coated.

-------

Cutting Off - odd tooling ideas [atlas_craftsman]
Posted by: "Bruce ." freemab222x~xxgmail.com bakmthiscl
Date: Fri Dec 5, 2014 3:36 am ((PST))

This is a reality check for me.

A couple days ago I was cutting off a part in my 10" Atlas lathe (5-inch
for those of you across the pond). I had my usual cutting-off problems,
nothing major, which are mostly due to my inexperience with the technique.
Hence, when I was getting toward the center, I had more problems, so
switched to a hacksaw.

Initially I was just going to saw through the neck to free the part, but
then I figured, "Why not spin the part to make the cut even?" and did so.
(I used a sawing motion throughout lest the teeth clog.) It worked fine. I
couldn't help noticing that the hacksaw blade made a cut less than half the
width of the cut-off tool bit, and that got me thinking. (Dangerous
ground! Proceed with caution!)

Why NOT a hacksaw attachment to a lathe? Something that would move a
standard hacksaw blade (under tension from a frame) back and forth
(preferably lifting it slightly on the return stroke -- an easily
accomplished feat). The advantage would be the narrower cut and NOT having
to deal with persnickety cut-off tools which have to be well centered,
firmly mounted, etc. A hacksaw is so much more forgiving!

Now before you jump ahead, I did consider the possibility of a rotary saw
spinning in the same direction to the workpiece (i.e., the touching
surfaces would be going in opposite directions). That would be easier to
accomplish by taking power directly from the lathe rotation (by any of
various means). However, a rotary saw blade is not under tension and I can
foresee many more difficulties in its use.

Now, I wouldn't bother pulling power from the lathe to operate a hacksaw.
For my work, powering the hacksaw by hand is sufficient, but automating it
would be nice. For that, I'd probably modify some commercial motorized
hacksaw (like my Atlas-Craftsman one, for example, though I wouldn't want
to gut that machine for the task).

In use I'd envision doing a very shallow initial cut, possibly with a
fixed single-point tool, the tip of which is the same width as the
hacksaw kerf. This is just to make a start for the hacksaw blade, so
needn't be at all deep -- maybe as deep as its width. (If the hacksaw
were rigidly mounted to the lathe bed, it might be possible to make this
initial cut with the stationary or hand-powered hacksaw.)

>From there I'd switch to the hacksaw, powered either by hand or from a
>motor.

I find most of my great ideas are stolen before I even think of them!
I'm hoping that this was one. Does anyone know of this being done or even
described in some text?

Bruce   NJ

-------

Re: Cutting Off - odd tooling ideas
Posted by: "Rick - yahoo" rgsparber.yax~xxgmail.com rgsparber
Date: Fri Dec 5, 2014 6:57 am ((PST))

Bruce, This is a great idea!

Ideally you would use an unmodified hacksaw blade and could stop the cut
at any point. If the blade was supported by the apron and the angled up
slightly, then feeding in with the compound would also lower the blade
into the work. Still need a way for the blade to move back and forth.
You sure have me thinking….

Thanks,
Rick

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Re: Cutting Off - odd tooling ideas
Posted by: "Bruce ." freemab222x~xxgmail.com bakmthiscl
Date: Fri Dec 5, 2014 2:04 pm ((PST))

Yup! But one could always move a powered hacksaw up to the lathe and bolt
them together somehow. It would take some modification to the powered
hacksaw, of which there are lots of examples on the market -- and at the
flea markets. Also, I there are plans by Vince Gingery available:
http://www.amazon.com/Build-Power-Hacksaw-With-Vise/dp/1878087126
(I haven't examined these myself.)

Bruce   NJ

-------

Re: Cutting Off - odd tooling ideas
Posted by:  david.deboizex~xxverizon.net inspiro_creo
Date: Fri Dec 5, 2014 5:59 am ((PST))

Bruce in NJ, this is  David in NJ (Cumberland Cnty). I can't recall when,
but I did remember seeing this idea. Please look at the YouTube video
link below.

https://www.google.com/url?sa=t&source=web&rct=j&ei=friBVO36I8-dyASG
iYGQCA&url=http://www.youtube.com/watch%3Fv%3Dti4N3FabLMs&ved=0CCYQ
twIwAA&usg=AFQjCNGGeOzAsuEHW89maypQUR5Z0Li73g&sig2=lbDhkO4ZApcBez9UTPapaw

Also while in YouTube search "hacksaw lathe", there's also 3-4 other
videos on this subject.

-------

Re: Cutting Off - odd tooling ideas
Posted by: "Bruce ." freemab222x~xxgmail.com bakmthiscl
Date: Fri Dec 5, 2014 2:01 pm ((PST))

Well, that's a hacksaw powered BY a lathe. (It doesn't seem to cut very
well.) That's not what I'm proposing.

Bruce   NJ

-------

Re: Cutting Off - odd tooling ideas
Posted by:  david.deboizex~xxverizon.net inspiro_creo
Date: Fri Dec 5, 2014 6:59 pm ((PST))

True, I noticed the same thing. Looks like user made it all out of
aluminum. No weight to cut anything in my opinion. Knowing that one was
powered by the lathe, thought it might give an idea as to power it via
separate motor and use the design to incorporate into the lathe.

Also I can't see using the compound as a vise. Just ideas to throw around.

-------

Re: Cutting Off - odd tooling ideas
Posted by:  wa5cabx~xxcs.com wa5cab
Date: Fri Dec 5, 2014 9:45 pm ((PST))

If you have the milling attachment, you can use the vise off of it on the
cross slide pintle. Besides being sturdier, it lowers whatever you are
mounting by about an inch, reducing the CG and the moment about the
pintle. My adapter to use a Dremel tool as a tool post grinder fits the
vise, which made it easier to get the grinder on center and made the
adapter stronger.

Robert Downs - Houston
wa5cab dot com (Web Store)   MVPA 9480

-------

Re: Cutting Off - odd tooling ideas
Posted by:  jerdalx~xxsbcglobal.net jtiers
Date: Sat Dec 6, 2014 6:27 am ((PST))

If one insists on not doing cutoff the normal way, possible the best
alternative in the path of this thread is to put a live spindle on the
crosslide and cut off with a rotary slitting saw. That reduces the issues
of tooth clogging, since the cutter tends to sling off clogs. One with a
tooth size similar to a 7 to 12 tooth per inch saw probably will not clog
much on larger pieces.

The lathe spindle would not even have to turn. The rotary saw would have
a lot less "monkey motion" than any sort of reciprocating saw. You might
even be able to run it from the lathe spindle by a belt system.

However, regular cutoff'part-off tools have worked well for over 100
years. If yours do not work, then there is most likely a fault in how they
are being applied.

Cut off close to the chuck or collet. Set the blade square to the work
(reference the chuck face, for instance). Set the blade on-center so it
leaves no nib. Stick the blade out the least possible. Have the topslide
and toolholder solidly over their bases, not hung out over open space.
Lock the carriage (should be obvious, may not be). Run at the slowest
normal (non-back-gear) speed, a couple hundred rpm. Consider getting a
carbide insert parting tool. It's one place carbide works well, partly
because it gives good side relief.

Feed by hand, at least at first, and don't be shy about a heavier feed if
that makes it work better and doesn't stall the lathe. Power feed is fine,
maybe better, once you develop a good routine by hand feeding and know the
materials and appropriate feed rates for your tooling and lathe.

An Atlas is a very lightweight lathe, but it should do OK parting off in
the 2" and below diameter range. Maybe 1" and below for the 618.

Jerry

-------

Re: Cutting Off - odd tooling ideas
Posted by: "Rick - yahoo" rgsparber.yax~xxgmail.com rgsparber
Date: Sat Dec 6, 2014 7:25 am ((PST))

What I find attractive about using a hacksaw to part off is the reduction
of waste when small parts are made. Say I make a part with an OAL of 0.25”
and I must part off with a 0.187” wide parting tool. I’d much rather use
a hacksaw blade in tension that is maybe 0.05” wide. The trick is to keep
it simple.

Rick

-------

Re: Cutting Off - odd tooling ideas
Posted by:  wa5cabx~xxcs.com wa5cab
Date: Sat Dec 6, 2014 8:29 am ((PST))

I normally part off with an .062" ThinBit. But I have used an .031" on
thin wall tubing/bushings.

Robert Downs - Houston

-------

Parting tools and the top slide [myfordlathes]
Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac
Date: Tue Jan 27, 2015 8:16 am ((PST))

G'day all, I turned up a pulley tonight to replace one I broke on the
weekend in a fit of ham fisted stupidity.

I turned it up out of 75mm mild steel bar and one of the tasks was to
cut quite a deep slot. I figured the best way to do that was using a
parting tool. I spent 5 hours at the lathe tonight, and 3.5 of those was
cutting that damn slot and parting off the bar.

I'm using a chinese dixon clone toolpost and a parting blade holder from
RDG. Because I was parting 75mm bar, I had the blade extended a fair way
which when it bit in, enabled a pretty severe lever action on the
toolpost and top slide. I noticed the top slide actually tilting forwards
(so lifting at the handle end) and in extreme cases the tool holder was
pulled slightly away from the tool post (I could slide a thin feeler gauge
between the two).

When I'm not doing a task that requires use of the top slide, I keep the
gibs done up pretty tight. I started the job without the back gear
engaged and I got a lot of chatter. One odd thing I noticed is even with
the gibs done up tight, when there was chatter the top slide would move
about on its own (like the feed screw would rotate and it moved back and
forwards). When the lathe was stopped I could barely move the slide
myself, so things were still tight.

I slowed things down with the back gear which eliminated the chatter,
but then things would flex so much the blade would bite in and when that
happened things came to a screaming halt. (I have the headstock belt
slightly loose on purpose to buy me some leeway when I do something
dumb.) This happened a lot and I started to watch the tools and slides
as I wound the spindle back by hand, and that's when I noticed the tool
holder moving slightly, but the top slide rocking more noticeably.

I bought a rear parting blade holder from RDG recently, but because I
have the short cross slide I'd have to remove the top slide entirely to
get clearance to part off the 75mm bar, so I stubbornly did it from the
front. Between lots of flex and snapping a parting blade, the whole
process was just painful.

Has anyone got any suggestions for dealing with the top slide rocking
like that? I can see I'm going to have to get a proper A&R Dixon style
toolpost and holders, but I can't see a way to stop the top slide moving
about without bolting it down entirely or dropping it and moving to a
gibraltar style tool post.

On the up side, I made lots of swarf tonight, wound up with a black
stripe down the left side of my shirt and spent lots of quality time
with the machinery, so it was not a total loss.

-------

Re: Parting tools and the top slide
Posted by: "Peter Dobson" peterdx~xxmodelrail.net peter317217
Date: Tue Jan 27, 2015 8:36 am ((PST))

Have you checked the fit of the topslide to the cross slide.

I had a number of problems with digging in and found that far from a flex
in the toolpost etc for which everyone yells 'fit a pitkin donut' I
actually had a problem with the fit of the top slide dovetails on the
side opposite the gib strip.

The topslide was fine until I tightened up the gibs whereupon the back of
the slide lifted up and it was possible to fit a feeler gauge between
slide and the base.

This was solved by removing the topslide from its base and filing the
sharp edge so it was considerably less sharp. This cured the problem.

The modification allowed the two sloping faces to touch while the two
base faces were still touching.

If that is not clear then I will try and produce a drawing.

regards
Peter Dobson

-------

Re: Parting tools and the top slide
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood
Date: Tue Jan 27, 2015 8:48 am ((PST))

Hi Brad, I use a Q-Cut parting tool on my S7 in a Dickson toolholder, and
provided I have aligned it properly perpendicular to the axis I have
absolutely no problem parting off mild steel under slow-ish direct drive.
I have a VFD fitted and mostly leave the lathe in top speed of the low
belt range, and use the VFD to vary speed. I'll use anything from 75 to
3-400 rpm depending on diameter. Have a rear tool post, never needed it.

It does depend on everything being well aligned and tightened, locking
everything you are not using. What could go wrong? Well, in turn:

(1) The ML7 headstock bearings are not as robust as the S7 ones (I guess
that's what you have as you mention the short cross-slide). Have you
checked it?

(2) The cross slide adjustment is also important. The best way to check
it is to remove the feed screw by unbolting the front bracket, and
tightening the gib strip until you can just push it along its range by
hand, but with no trace of sideplay. Anything tighter than this just
promotes wear, anything slacker will allow chatter.

(3) The tool should overhang as little as possible, and on a larger job
it would be worth doing it in 2 or 3 stages, pulling the tool further
out as you go.

(4) It must be absolutely perpendicular to the lathe axis.

(5) The tool is crucial; if you have not tried it, get one of these:

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

It is by a huge margin the best parting tool I have used, out of many. I
saw the Myford (old Myford) chaps parting off under pxf at 400 rpm with
one of these, and it was smooth as butter. The only reason I don't use
pxf is that my lathe doesn't have it! The critical feature of the tool
is the tip, which is shaped to curl the swarf in on itself to remove the
tendency to jam in the cut.

(6) Cutting oil is helpful; I use a drip feed of neat cutting oil, just
drip a drop or two every few seconds.

Having said all that, 75 mm is a bit of a stretch for a Myford ML7. Two
further suggestions: If you are at all uneasy about the chuck, hold it
in a 4-jaw independent (firmer grip) and consider using a Gibraltar type
toolpost:

http://www.hemingwaykits.com/acatalog/Gibraltar_Tool_Post.html

You'll still have to take care of the cross slide adjustment, but the
top slide will no longer be a concern!

Finally, if all else fails, make friends with someone with a bigger
lathe! I must admit I'm in the fortunate position of having a larger
lathe (a 6.5" Harrison M300) so I part big stuff off on that, but I'm
sure my S7 would cope if I observed the above points.

Good luck,
David

-------

Re: Parting tools and the top slide
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood
Date: Tue Jan 27, 2015 9:00 am ((PST))

Just one further thought on how to do the cut. In difficult situations,
it is worth plunging the tool in twice at slightly different positions
of the saddle, to make the groove wider than the tool. If you do this
for say the first 50-75% of the depth, you should be able to finish off
the cut at one setting. I used to do this regularly when I used a
traditional parting tool. It reduces the drag on the tool, and allows
for a trace of deviation from exact perpendicularity of the tool.

David Littlewood

-------

Re: Parting tools and the top slide
Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac
Date: Tue Jan 27, 2015 4:56 pm ((PST))

G'day David,
This is exactly how I was doing it. Before I got a real parting tool I
was using a bit of 5/16" HSS ground to a parting tool at the end and as
my grinding was less than stellar I needed to use this technique to
guarantee side clearance. I just kept doing it when I finally got a
proper parting blade.

I also stone the sides of the blade so I can use the spring in the blade
to do a bit of sideways cutting to give me a bit more clearance at the
bottom of the hole. I discovered the advantage of cutting fluid last
night and I also had great results positioning my shop vacuum to
evacuate the chip as it came off. I did start with less overhang and
then pull the blade out as I got deeper. I had a rotating centre for
support which stopped the piece trying to walk out of the chuck jaws and
allowed a precise re-seating after a good dig in.

Yes, 75mm was a big ask. About half way through I seriously considered
breaking out the sabre saw to finish it off. My neighbour has a couple
of *big* lathes (like 300mm centre height, ~90mm spindle bore and 2M
between centres), but I really wanted to show myself I could do it on
the "little Myford that could".

The cross slide is very well adjusted, I recently re-shimmed the saddle
to take out the lift and cleaned up the mating surfaces between the top
slide & cross slide. I'll pull the top slide off tonight and check the
fit with some blue though.

Appreciate the advice.
Regards,
Brad

-------

Re: Parting tools and the top slide
Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com
Date: Wed Jan 28, 2015 2:17 am ((PST))

Hello Brad,
Yes, 75mm is a big ask for a Myford, probably too big. I would be
inclined to take the coward's way out and hacksaw the last bit.

As a general point, on a not-very-rigid lathe like a Myford deep parting
off using the front toolholder is always going to be a nerve-wracking
operation, with an ever-present risk of jam ups and damaged work. Most
users invest in either a rear toolholder or a replaceable insert parting
tool. The rear toolholder allows the tool to be mounted upside down,
with the result that as the load increases the tool tip tends to get
thrown out, rather than digging in. Why the insert type tool doesn't dig
in like an ordinary HSS tool I have no idea, but believe me, they are
magic!

Just one other thing. If you do use a rotating centre in the tailstock
for support you should back it off before you do the last bit of parting
off, otherwise you are likely to get an almighty jam up as the end
breaks off.

Regards,
Alan

-------

Re: Parting tools and the top slide
Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk ukdiverbob
Date: Wed Jan 28, 2015 2:50 am ((PST))

Hi. Regarding parting off. As an option, parting off a large diameter
would be way down my list. It all depends on what else you can do.

I'm going to assume that all you have open to you is your lathe and a
hacksaw. My preferred method in this case would be to use a combination
of a "V" shaped tool and parting tool.

Go in initially with the "V" tool and then with the parting tool.
"Spreading" the cut made by the "V" tool.
This will require a wider and more wasteful "groove" to be cut, but it is
far less likely to break the tool.

Again, depending on the job, approach the parting off at an early stage
and make the groove while able to support the job with a centre. A 75 mm
diameter bar could be safely cut down to 20mm at the bottom of the groove
and still be rigid enough to machine the whole of the rest of the job
later. Hope this makes sense.

Regards
Bob

-------

Re: Parting tools and the top slide
Posted by: "Richard Wilson" richardpwilson61x~xxyahoo.co.uk
Date: Wed Jan 28, 2015 4:48 am ((PST))

I'm a recent convert to replaceable insert parting tools, and it's the
best money I've spent for a long time. Care is still needed regarding
the setting height, it needs to be dead on centre, as if the tool is low,
and 'drags' under the final pip, then the end of the insert will chip
off. Even then all is not lost, as I've found the inserts can be touched
up on a green grit wheel, and restored to use. The limit seems to be
about 4 grindings before a new tip is needed.

For deep parting, I start the groove at 2 x tool width, gradually reducing
as the depth increases, to avoid jamming. For 75 mm, I'd definitely use
tailstock support, but stop when about 3/4" is left, then put the work in
the vice and hacksaw the rest. Even on my Denford 280, which is capable
of parting all the way on 75mm, I'd saw the last bit, mainly because I
don't fancy a revolving lump of 75mm stock breaking free.

Richard

-------

parting off problems [myfordlathes]
Posted by:  gertjan.aaftinkx~xxgmail.com dutch_anglophile
Date: Sun May 24, 2015 12:39 pm ((PDT))

Hi all, I've rebuild an 1957 ML7, which now works fine for normal turning.
However, parting off, it does not so good. I first used a 'normal' parting
off tool (the small HSS blade in a quick change toolpost holder). I've
built the Hemingway rear tool post, with which the paring off is done
upside down. Both methods give the same result: the tool often grabs the
work. With the rear tool post you can see the tool post flexing upward.
The cutter mostly rubs along the piece, if I increase the feed slightly
it grabs. There is almost no in between. I've tried different rpms,
different feeds, I'm using lubrication. I lock down the saddle. Whatever
I do: parting makes a sound like firework: I think it constantly grabs and
breaks free again. And sometimes it grabs and all stops.

I've tried so many set-ups that I no longer think it is only me being
inexperienced that gives this result. Could it be that the spindle
bearings are worn to a degree that the play (which I cannot feel btw)
enables the piece to flex towards the cutter, creating the grabbing?
I'm thinking that way because when I do milling on the lathe the cutting
is also no straight under anything but a very light load.

Any suggestions are appreciated,

GJ

-------

Re: parting off problems
Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk ukdiverbob
Date: Sun May 24, 2015 1:02 pm ((PDT))

For what it’s worth, my two pennies.

My initial turning experience was on big old lathes that had seen loads
of service and were well past their best.

Attempting to part off without spreading the cut was doomed to failure.
I would use a tool that was either Vee shaped or with a radiused end that
would allow spreading easily, until I got to a point that was almost
through and then finally resort to the parting tool.

To be honest though, with a rear mounted parting tool and the saddle
locked up, I wonder if the material is giving you the problem. Free
cutting mild steel is a revelation.

There will be gasps of disbelief, but try raising the rear mounted tool
slightly above centre too.

You speak of increasing the feed????----maybe the speed, but not the feed.

Regards
Bob

-------

Re: parting off problems
Posted by: "Mike Waldron" mikex~xxmjwsjw.co.uk pastor_mikew
Date: Sun May 24, 2015 1:13 pm ((PDT))

Could it be too much front clearance on the parting tool?

Would that, plus generous top take would tend to encourage digging in?

Mike W

-------

Re: parting off problems
Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com
Date: Sun May 24, 2015 3:35 pm ((PDT))

Dear GJ, This subject has been raised quite a few times in this group,
but it doesn't hurt to repeat the advice. Parting off with conventional
tooling is always difficult due to the drag on the sides of the tool as
it goes deeper into the work. The rear toolpost doesn't solve this
problem - it just makes the consequences of a jam less severe. You can
make life easier by widening the cut, ie. go in some distance, retract
the tool and move it by half the tool width, then go in deeper, retract,
move half the width in the other direction, etc. This gives you a slot
of one and a half times the tool width and stops the binding with the
slot sides.

The final answer to your problems is the indexable parting tool. This
uses a ceramic insert which is wider at the front than anywhere else,
so it cannot bind in the slot. Look on the CTC Tools website
(www.ctctools.biz) for a couple of alternative designs. Their prices are
very reasonable and the quality is pretty good. Once you have tried one
of these tools you will never go back to the old style!

Regards,
Alan

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Re: parting off problems
Posted by: "leslie thurman" leslie.m.tx~xxtalktalk.net
Date: Mon May 25, 2015 12:21 am ((PDT))

Hi. I seem to remember that I used to grind just a fraction off the
widest part of the blade to within, say 1/8 inch of the cutting edge,
to allow a few more re-sharpenings, -- it seemed to work -- just a
thought--  (parting is such sweet sorrow).

LT

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Re: parting off problems
Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com
Date: Mon May 25, 2015 2:42 am ((PDT))

Dear GJ,
I'm aware that in my reply yesterday I did not touch on the subject of
loose headstock bearings. If you have this problem it will certainly add
enormously to your parting off difficulties, as the work will try to
climb up over the tool and make it dig in. You cannot really check
bearing play by hand. Run the lathe for several minutes to warm up the
bearings, then you need to put a stiff (large diameter) test piece in
the chuck, set a dial gauge on the piece close to the chuck and look at
the change in reading as you pull and push the piece firmly in different
directions. You need to do this firmly, as otherwise the oil film in the
bearing can make you think it is tighter than it really is.

ML7s have white metal bearing shells and the play is adjusted by
removing layers from a shim pack between the bearing halves. Adjusting
them is a matter of repeated trial and error, and it is probably best to
remove one layer at a time, tighten up, retest, etc. until the shaft is
tight to turn by hand, then add one layer back. However, I am not an ML7
owner, so I will leave it to more expert people to advise you on the
best method.

Regards,
Alan

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Re: parting off problems
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood
Date: Mon May 25, 2015 3:58 am ((PDT))

My own personal experience (with a S7 only a little younger) was not
quite as bad as yours, but was still rather hit-and-miss. I tried
several parting blades, and all gave problems to some degree or other.
Then I bought a Q-Cut tool, see here:

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

It was like entering a new world. Provided it was set correctly, I could
part off under direct drive (whereas before backgear was essential). If
I had power cross feed I could have used that -- I saw the Myford folk,
using the same tool, parting off a chunky mild steel bar at a speed I
would previously have regarded as impossible.

Accurate setting is important; tool height, obviously, but even more
important is to get the toolholder exactly at right angles to the lathe
axis. Lock saddle and, if you can, the topslide. Apply suitable cutting
fluid (for MS, I use straight cutting oil, dripped from a squeezy
bottle). Now I regard parting off as just another straightforward
operation. I even bought an equivalent tool for my larger lathe, on
which I do part off under pxf.

Obviously, if your spindle bearings are in poor condition, you need to
do something about this first; any turning will give you trouble if the
bearings are shot. I'm not familiar with the ML7, but Alan's advice
looks good.

Rear tool posts? I've never been convinced of their attraction. If you
use the right tool, set correctly, it should be fine in what you might
call the missionary position. I do have one, but it's too much of a
nuisance.

David Littlewood

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Re: parting off problems
Posted by:  alighazizadehx~xxaol.com lensman5719
Date: Mon May 25, 2015 4:43 am ((PDT))

I also have an ML 7 of the late 40s vintage. Like you parting off is a
nightmare using a conventional blade. Last month before I retired the
lathe for a major overhaul which is still on going I managed to very
successfully part off a 30 mm bar of Stainless steel about 3 inches from
the chuck with the support of fixed steady and using an indexed carbide
tool. The chips were short curls just coming off the tip. I also made sure
the top slide was properly locked and the cross slide gibs tightened up so
the advance required a bit of force.

I seem to have much better success parting 25mm steel on my Taig micro
lathe than than the ML7. I also believe that the HSS blades supplied as
standard for parting with the various tool holders are much too thick to
be used on these old machines. I much prefer the Eclipse 1/16” thick for
doing the jobs. A few years ago I bought a rear post parting tool holder
that came with a 1/8” thick blade of 1 1/2” width, I have never used this
tool as it is impossible to part with it.

Regards,
A.G

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Re: parting off problems
Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk ukdiverbob
Date: Mon May 25, 2015 5:52 am ((PDT))

While the Myford is a very lightweight machine, its spindle will lay on
the bearings when at rest. Cutting “upside down” keeps it there. Cutting
right way up will attempt to lift it. I do think that a spindle correctly
adjusted will have little or no clearance, but anything that assists is
surely a positive.??

I have no experience of indexable (is that the correct term) parting tools
and only minimal experience with the high speed steel blades used in tool
holders. I do have plenty of experience with Digging In and swarf Jamming
Up resulting in broken tools though.

I suppose there are plenty of reasons to require parting off and not
spreading the cut, I for one would never go that way unless it was
essential.

There was mention of using a particularly thin blade. If that is needed
then I would suggest there is another problem, or problems with the
machine.

This all takes me back many years to a job cutting discs about 10”
diameter with a bore of about 3” out of ˝” stainless plate on a Horizontal
borer. Without going into the whole sorry saga there were many, many
parting tools snapped in the process. Using a Vee tool would have been
far safer, with the OD being finished off in a lathe later. Hindsight is
a wonderful thing.

Bob

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Re: parting off problems
Posted by:  gertjan.aaftinkx~xxgmail.com dutch_anglophile
Date: Mon May 25, 2015 10:31 am ((PDT))

Allen, well the results of digging in may be limited using a rear
toolpost. But today I found out that also a rear toolpost can give bigger
problems. When trying higher rpms the cutter broke. I was lucky not to be
in its way.

GJ

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Re: parting off problems
Posted by:  gertjan.aaftinkx~xxgmail.com dutch_anglophile
Date: Mon May 25, 2015 10:28 am ((PDT))

Bob, Yes, I noticed once that some steel is much easier to finish nicely,
and probably parting off is easier. I'm currently using pieces of
construction steel. I've no idea how to get this free cutting steel.
Here I only found the construction material and that definitely does not
result in a good finish for normal turning (although it is acceptable).
Where can you buy this free cutting steel?

Regards,
GJ

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Re: parting off problems
Posted by: "Robert Mitchell" rmm200x~xxyahoo.com rmm200
Date: Mon May 25, 2015 11:05 am ((PDT))

Check online of course, and look for a supplier in your part of the world.
One in America / Canada is:
https://ecommerce.metalsupermarkets.com/catalog/STEEL-COLD_ROLLED/RO
UND_BAR/12L14

Note that I pointed the URL to 12L14, which is also known as leaded steel.
Free cutting. This company carries bar, hex stock, and plate in small
quantities.

Robert Mitchell

-------

Re: parting off problems
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood
Date: Mon May 25, 2015 12:18 pm ((PDT))

We don't know where you are, but in the UK there are numerous firms who
specialise in supplying small to medium amounts of metals to model
engineers. I use Mallard Metals and Noggin End Metals, but there are
several others. You need to get some free-cutting mild steel, often
called by its old name EN1A in the UK, but its "new" name is, IIRC,
220M07. There are leaded varieties which give an even better finish. Odd
lumps of construction steel are almost always dreadful stringy stuff;
that's what I first tried when I first started lathe work 30 years ago,
scrounging it from scrap bins, but when I tried the decent stuff it was
a revelation.

There are more sophisticated steels for various purposes, but all are
more expensive than EN1A, and a little (or a lot!) tougher to turn; you
can look into those when you need them, and when you have got your lathe
bearings sorted.

David

-------

Re: parting off problems
Posted by:  gertjan.aaftinkx~xxgmail.com dutch_anglophile
Date: Mon May 25, 2015 12:48 pm ((PDT))

David, thanks for the info. I'm located in the Netherlands, and using
the 12L14 code I found an webshop that sells it here. It is called
'automatenstaal' here. I'll also have a look for the codes you mentioned.

Regards,
GJ

-------

Re: parting off problems
Posted by:  alighazizadehx~xxaol.com lensman5719
Date: Mon May 25, 2015 11:49 pm ((PDT))

12L14 is the American code for free cutting bright mild steel. In fact
judging by the quality of the blank arbours that came with my micro
lathe and are made of 12L14 steel I would say that it cuts much better
than the ordinary EN1A or EN1Apb which the leaded version so if you have
access to 12L14 then it is the way to go.

A.G

-------

Re: parting off problems solved
Posted by:  gertjan.aaftinkx~xxgmail.com dutch_anglophile
Date: Mon Jun 1, 2015 10:15 am ((PDT))

Dear all, thanks for the many suggestions for solving the parting off
problems. In the weekend I reduced the play in the main bearings by
ADDING layers of tin foil to the shim packets. It turned out that the
shims were 0.24 mm too thin, so the main bolts of the bearing could not
be tightened. This resulted in the play in the bearing. Now that the
bearing is correctly shimmed the finish for turning is much better and
parting off is now possible. I'll check out the tools mentioned in the
posts, but all in all the problem is solved.

Regards,
GJ

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Re: parting off problems solved
Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com
Date: Mon Jun 1, 2015 10:24 am ((PDT))

Wow, 0.24mm is a lot! Glad you found the cause of your problem.

Alan

-------

Re: parting off problems solved
Posted by:  alighazizadehx~xxaol.com lensman5719
Date: Mon Jun 1, 2015 11:24 am ((PDT))

Hi GJ, I am glad you got it sorted. Just to be clear, did you add to the
shims or took away from them. I would have thought that if the bearing/
spindle was shimmed 0.24mm too low it would have seized up. I am only
asking this as I am about to reassemble my headstock with a newer spindle
and bearings and I have provisionally set it up with a full extra layer
of shims as it would not turn with just a single full layer when the
bolts were tightened and even now it is a little tight to turn by hand.

Regards,
A.G

-------

Re: parting off problems solved
Posted by:  gertjan.aaftinkx~xxgmail.com dutch_anglophile
Date: Mon Jun 1, 2015 1:32 pm ((PDT))

12 carefully cut layers on each side. You cannot see a difference to
the original shim layers.

-------

Re: parting off problems solved
Posted by:  gertjan.aaftinkx~xxgmail.com dutch_anglophile
Date: Mon Jun 1, 2015 1:41 pm ((PDT))

Hi, I've added shim layers. As it turned out I've tried to run the lathe
with the bearings bolts a little lose, otherwise the spindle would
lock-up. This gave room to the spindle to move around and work itself
under/on top of the cutter. I've added layers until I could spin the
spindle with the bolts tightened, and then (it rotates easier when oiled).
I've removed 1 layer on each side. So I've probably gone through the same
process you have. Although I did not need an extra shim set. What I tried
was: make sure the spindle just does not lock up. When turning, until now,
the bearing does not or almost not get warm. So I hope I've done all of
this OK.

Getting  a new spindle was my way-out as well if this would not have
worked out.

GJ

-------

Cross slide backlash / parting problems [myfordlathes]
Posted by:  garthnx~xxpbt.co.za garthn444
Date: Wed Jun 24, 2015 1:37 pm ((PDT))

Hello all
I've never had much success with parting off, but seem to be improving
since I installed a VFD motor (at least, with aluminium so far).

My cross slide had a horrendous amount of backlash - over half a turn -
the nut was very worn. I made a new screw which came out much better than
it had any right to, and also installed bearings.

Someone pointed out that a vertical slide nut was the same as on the cross
slide. Since I switched them, the backlash is now about 17 thou.

Is this a reasonable amount, will it work ok for parting off different
materials, or should I be making a new nut (and perhaps a new screw as
well)? I know I can just try - but I would like some advice though as to
whether this is a factor I can concentrate less on now.

Thanks
Garth

-------

Re: Cross slide backlash / parting problems
Posted by: "Robert Mitchell" rmm200x~xxyahoo.com rmm200
Date: Wed Jun 24, 2015 2:36 pm ((PDT))

Backlash is irrelevant unless the bit is being pulled into the work.
Watch your top rake.

My very worst luck with parting off is advancing the cutter by hand.
That is prone to jamming.

My best luck is with slowest direct drive automatic infeed with
lubrication. A uniform depth of cut going in is very important. I use
an Eclipse parting blade.

Robert Mitchell

-------

Re: Cross slide backlash / parting problems
Posted by:  garthnx~xxpbt.co.za garthn444
Date: Wed Jun 24, 2015 2:51 pm ((PDT))

I've implemented Tony Jeffree's CNC conversion design, so have power
feed. The tool sometimes jams into the piece and stops the lathe with
too high a feed and low rpm. The top rake was formed by grinding an arc
using the corner of the wheel - perhaps it is too severe.

I am however getting ribbons of aluminium coming off. And once or twice
I have had a really smooth finish. But also concave cupping. I've ground
the cutter (3/32) as square as I can and lined it up likewise.

The HSS blade I am using is tapered, but now I wonder if  the problem is
not that it is mounted in a tool holder which holds one side vertical,
so the other is angled. I was wondering about getting a t-shape cutter,
and shimming the bottom portion (rather top portion, I am using a rear
toolpost) to make the blade vertical.

Any advice would be appreciated - I feel I am getting there, have done
a lot of Googling, but would still like to get parting feeling comfortable
with a decent finish.

-------

Re: Cross slide backlash / parting problems
Posted by: "Kevin" tadpolex~xxbtinternet.com klokenz
Date: Fri Jun 26, 2015 10:24 am ((PDT))

Aluminium plus top rake plus more than optimal clearance in the
cross-slide feed arrangements doesn't sound good. Not all "aluminiums"
are the same of course, but there's a likelihood that the material will
be trying to draw the tool further into the cut. The feedscrew is
pushing the tool forwards, but if the material tries to draw it in then
it can suddenly move forwards by the amount of clearance in the
nut/screw, with the possibility of a jam. I'd get rid of the top rake.

If the tapered section blade is mounted off-vertical then the cutting
forces are off-centre too, which might well explain the concave cut.
Once you start bending the cutter like that (think of the force needed!)
there is rubbing of the tool on the sides of the cut too. I use a
tapered blade in a made-for-the-job toolholder that hols it upright.
Shouldn't be too hard to make a tapered shim to get yours properly
aligned.

When machining aluminium, using lubricant makes a big difference. The
usually recommended lubricant for this material is paraffin/kerosene.
In my own shop here in the UK I use "white spirit", which happens to be
more convenient (for me) and is rather similar, chemically.

Unlike some other workers I never set the parting tool above centre
height. A smidgeon above works for them, so that's fine. Just on
centre, or even a touch below works for me.

Kevin,  England

-------

Re: Cross slide backlash / parting problems
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood
Date: Wed Jun 24, 2015 4:57 pm ((PDT))

Garth,
I've never measured the backlash on my S7 cross-slide, but 17 thou does
sound a bit high. There was a chap on here a couple of weeks ago
offering replacement feed nuts, try a search on the archive.

Equally important, fitting of the gib strip. To do this, remove the
cross-slide feedscrew and adjust the gib until it slides smoothly be
hand, but with no trace of sideplay. To re-fit the feedscrew, screw it
home all the way before replacing the two screws that hold it in place;
that way, the screw will be correctly aligned (if you try to do it with
the screw at its outboard position, it's odds on that it will be
misaligned and get very tight or even immovable as you screw it in).

Finally, get one of these:
http://www.greenwood-tools.co.uk/shopscr23.html

I know it seems expensive, but it's the best parting tool of this size,
by a country mile, that I've used (and I tried a lot before I found this
one).

David

-------

Re: Cross slide backlash / parting problems
Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk tonyjeffree
Date: Thu Jun 25, 2015 1:43 am ((PDT))

> I know it seems expensive, but it's the best parting tool of this size,
> by a country mile, that I've used (and I tried a lot before I found this
> one).

I second that -  it works very well indeed. It is a bit pricey, but on
the other hand, I think I am only on my second insert tip in about 10
years.

Regards,
Tony

-------

Re: Cross slide backlash / parting problems
Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood
Date: Thu Jun 25, 2015 4:37 am ((PDT))

I think I may still be on my first, after a similar period. I suspect I
may do less work than you though Tony.

David Littlewood

-------

Re: Cross slide backlash / parting problems
Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk tonyjeffree
Date: Thu Jun 25, 2015 4:43 am ((PDT))

It was because I damaged the tip through careless use (not smart using it
on interrupted cuts!) and not because it wore out.

Regards,
Tony

-------

Re: Cross slide backlash / parting problems
Posted by:  red-rosex~xxgreenview.fslife.co.uk
Date: Thu Jun 25, 2015 1:28 am ((PDT))

Good morning all,
I would suggest that spending vast amounts of money to achieve successful
parting off is the wrong way to go about it.

Aluminium should be easy to part and you are getting ribbons so your tool
is good. Concave face; you don't say how thick the job is. I have trouble
with parting aluminium with a cheap 3/8" deep blade front parting tool at
anything more than 1.5" diameter. This is because of the tool overhang
being deflected which causes the concavity. The trick is to cut in
sections; first slightly behind your mark then stepped behind that, just
under the width of the tool, then the first cut again about 1/4" deep at
a time. when you are about 1/4" from through, line the tool with your
parting length and, in effect, face cut through the job.

Strangely, I have no problems with steel, just aluminium.

It always seems a waste to part off with a thick blade but that is where
you get rigidity. To be honest, I use a rear mounted 5/8" deep blade
parting tool, and have no problem, but I still use the step method on
aluminium for anything above 3" diameter. I keep the 3/8" tool for cutting
grooves. Lubricant, and CONSTANT FEED. Keep winding the tool in otherwise
it will grab and dig in (sounds illogical but when you stop you raise a
burr and this is what the tool grabs) or fine swarf will jam the tool in
the slot, breaking the tool.

One of the advantages of rear parting (I have found several) is that swarf
drops out of the slot rather than jamming in it.

If you can find the time and concentration, you can grind your own from
HSS blanks. These have far more rigidity than the blade types, but
grinding them accurately takes time.

To be honest (again) I have gone back to HSS from carbide inserts and
spend a little time every so often grinding tools off-hand, sometimes for
a particular job or just to understand better what I am doing; I also have
a Drummond hand shaper so nothing gets wasted. The trick with grinding
your own tooling is not to let it get hot. Have a pot of water for dunking
the tool in when it is hot to the touch - that is relative I know, I have
thick skin so my hot may be a higher temperature than yours...or lower!
Don't let it go to blue. Swirl the tool in the water until it is cool then
grind again.

I don't have a (hugely expensive) tool grinder; everything is done by eye
on an off-hand grinder with a straight edge and a square standing by for
checking as I go.

I hope that this helps.
Andy

-------

Re: Cross slide backlash / parting problems
Posted by:  peterroachx~xxbtinternet.com x3cnc
Date: Fri Jun 26, 2015 1:32 am ((PDT))

Hi, Agree with most of that, other that the constant feed. Steady feed but
increasing feed rate, or spindle speed if you have VSD, as the diameter
deceases. On CNC it is the CV setting. The data on the Greenwood site a
good starting point.

I recently had to part some DOMEX high strength steel tube about 400mm
dia, 6mm wall thickness (At work so not on the Myford). After several
attempts with tip tools that did not like the intermittent cut (tube not
perfect circle), using a standard HSS eclipse type parting tool worked.
Having blunted, lost the edge on the tool after two part offs, the
toolmakers reground the tool, on the side of a surface grinding wheel.
Whilst not showing any colour and the geometry being right, it got too hot
and is now not fit for purpose.

Keep the tool very cool when grinding. I will have to get the parting
blade re-heat treated or replace. Tube now being laser cut. HSS will work
but don't destroy the heat treatment with more heat.

Regards
Peter

-------

Re: Cross slide backlash / parting problems
Posted by:  garthnx~xxpbt.co.za garthn444
Date: Tue Jun 30, 2015 2:30 pm ((PDT))

Thanks all -- I found that with the reduced backlash using the replacement
nut from my vertical mill, the cut was very smooth on a 10mm piece of
steel. The first time I have had successful parting off. I have realised
this is one case where backlash cannot be ignored even using CNC -- I
previously had catches on steel and aluminium.

I'm now on a mission to reduce the backlash to a minimum by making a new
screw to match the worn nut.

-------

Re: Cross slide backlash / parting problems
Posted by: "David Everett" dernhx~xxyahoo.co.uk deverett2003
Date: Wed Jul 1, 2015 1:38 am ((PDT))

If you are feeling challenged on screwcutting acme threads, there could
be a simpler way to make your new nuts, using Acetal.

http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-lead
screw-nuts-the-easy-way

Dave   The Emerald Isle

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