View Full Version : Chatter while tapering barrels.
02-20-2009, 04:20 PM
Ok, I make quite a few barrels here in the shop, Round, Octagon, 1/ 2 Round etc, the barrels I hate the most are tapered round, for one simple reason chatter.
Iím looking for a way to cut out the chatter when tapering round barrels in a lathe. The folks that have done this probably know what Iím talking about. When you put a 26 or 30 inch BBL between centers, you get to the center of the barrel and it acts like a wet noodle. Now this is a semi production environment, time is money.
Yes Iíve messed with Speeds, feeds, HSS and Carbide, different nose radius on tools, and etcÖ. I know the "big boys" grind their barrels, and I'm considering this, I've got the grinder..not sure that I want to dedicate a lathe to this.
Iím thinking another solution to this problem is a spring loaded or hydraulic follower rest. Has anyone built one of these????
02-20-2009, 04:50 PM
Even a standard follower rest would help cut the chatter on the long taper cuts. Without a follower rest, I would think there is a fair amount of "spring" in the barrel when you are cutting with such a large distances between end supports. I would think that this "spring" would contribute to the chattering.
02-20-2009, 08:24 PM
Of course, using a standard follower rest will not work because the barrel is tapered and will actually push the barrel as it works along the taper.
02-20-2009, 08:54 PM
I have only tapered large diameter barrels, 1" half octagon. There was minimal chatter with them.
With smaller diameters, I am sure there is a chatter problem. Perhaps something as simple as a spring loaded follower cobbled up out of a 2X4 for instance might be adequate to damp things enough to get a decent surface finish.
I've tried it and found the same problems as you. I'm not sure anyone could turn a barrel down of that length without chatter on a regular lathe.
It's my understanding the big barrel makers do use a hydraulic follower of some type, but I've never seen one. I'm not so sure they "grind" a barrel, they turn them.
Since I only chamber barrels and not make them, I order them tapered the way I want them, generally. The odd occasions I've turned one or two down is for my own entertainment. Not something I would want to do on a regular basis.
02-21-2009, 01:12 PM
I see you have asked the question on a couple of other forums without much help there either.
I have never seen either a hydraulic or a spring loaded follow rest, but have been thinking more about a spring loaded one. It would not need to have as wide a range of adjustment as a convential follow rest as the diameters will be in about the same size ranges, so that simplifies things a bit. A stout vertical flat or rectangle with a V piece to follow the work should handle most sizes.
I can picture a follow rest like that, hinged about halfway between the bed and the lathe centerline. On either side of the hinge joint, a piece of flat welded pointing to the rear of the lathe with a stout spring, like a valve spring, between them to force the follower toward the work. A piece of all thread through the spring to adjust the tension and position should complete the project.
02-21-2009, 02:06 PM
Douglas barrel blanks are normally furnished "as turned", Shilen's are (or were when I spoke with Dough Shilen about them several years ago) belt sanded.
Jim, on your spring loaded follow rest, I don't know that I would want to go with a hinged arm for the rest, as changes in position/tension could possibly create vertical error in it. If you do it with a vertical piece of square tubing and a piece of round bar in a "T" shape, you could have a spring loaded plunger in a bored hole in the top bar, set at center height. Think I'll start scrounging some materials, even though I don't do much taper turning with only an 11x24" lathe.
02-21-2009, 02:33 PM
Just thinking out loud. Mike hasn't gotten much help with the question on other sites and you have to start somewhere. It should not be too difficult to cobble something up.
There should be some float in the follower I agree. It could be nothing more than a piece of flat brass or UHMW as all it really needs to do is damp the chatter.
02-21-2009, 03:03 PM
Mike I've been there too, now days I get my barrels from these guys.
http://www.rifle-barrels.net/ They will contour them to anything you want and there laped after there contoured. They may charged more for one coustom contoured but as you said time is money, yours or theres. PS the finish on all I have goten from them has been first rate, I don't even polish them for BR rifles any more.
02-21-2009, 04:39 PM
Thanks on all the replies, I was thinking along the same lines. Think I may modify my current follower rest to a spring/plunger type arrangement, with a threadded end to adjust tension, and a brass tip to bear against the bbl.
I was Hoping that someone had run into the same problem that I have and has solved it...easily.
38 Cal & kurt...Thanks for the input. I make exact reproduction barrels for the old Winchesters, and unfortunately the barrels I make/supply are not what one would call "off the shelf"'. Cut rifling, 5 or 6 grove, specific land grove widths etc.
I've tried taking to the BBL manufacturers, they don't want to play unless I order 200 or so.
I've got an older guy with an old P&W rifling machine that supplies me with rifled blanks, I'll do the tapering & octagoning, threading chambering, roll marking etc here in the shop.
02-21-2009, 07:14 PM
Piggy backing on Dave's suggestion. How about an upright with an air cylinder working against the barrel. A large enough cylinder and shop air with a regulator might suffice.
I have a hydraulic tracer, I think you do too, they don't really use high pressure. Come to think of it, run a hydraulic line from your power unit to a hydraulic cylinder.
02-21-2009, 07:17 PM
I have seen your work Mike, its beautiful. You guys should check out his web sight. I think IIRC that the barrel makers do use some kind of hydraulic follower. Me, I have a OD grinder.
paul j smeltzer
02-21-2009, 07:38 PM
I have fitted and turned quite a number of barrrels since 1960. I found early on that it was a pain to turn barrels to shape. I built a 5 hp belt grinder with a back stand idler and 2"' X 72 " belts. To use the grinder, a mandrel was fitted to the action or chamber end of the barrel, a second mandrel made of copper was fitted into the muzzle end, both with a round handle extension. wearing a pair of leather gloves well oiled in the crotch of the thumb and index fingers. the handles were grasped the barrel presented to the belt at about a 30' angle, the barrel will then begin to spin quite rapidly if you let it. aplying pressure with your hands you can control the speed and therefore the grinding of the barrel. Buy starting with 40 grit and working down to worn 320 you can achive a "factory" look or continue on and polish. If I started with a unturned blank, I would turn the barrel down in long steps if necessary using a steady rest. then grind as above . From 1948 to 1960 I used the lathe for all tapering. Paul
02-21-2009, 09:26 PM
Well Im no Gunsmith But if youre inducing chatter when cuttin tapered Barrels perhaps (1) Youre trying to take off too much material at once,(2) is youre tool sharp (ex. new insert) or fresh sharpened Hss cutter? (3) rigid setup all tight /(4 ) Is tool on centerline of barrel>?% are you runing the correct feed and speed for the Particular Application? (5) We are assuming yopure lathe Bearings are up to snuff? (6Try lighter cuts what type of tool atre you using>? What type of material? It all plays a part. Sounds like a nice project.
02-22-2009, 09:20 AM
Yes I've messed with speeds, feeds, light cuts with HSS, heavy cuts with carbide, and just about everything in between. The barrels just pretty springy with 28 or 30 inches between centers., 22 Inches between centers seems to be my max before chatter.
I do probably 2-3 round and or 1/2 round barrels a month; so I do get some practice
As I mentioned earlier current practice is to do it inch by inch then blending, and its time consuming.
I WISH I had a tracer lathe that would really help with the carbine barrels, three different tapers on those .
I do have a Bridgeport tracer mill, wanna trade;)
Brought the follower rest in from the shop last night, looking at it, I think it would be fairly easy to make some ďspring ď fingers for it. Coil spring inside a cylinder pushing on a brass piston, the coil spring would allow for threaded adjustment to go inside the spring.
All....I appreciate all the suggestions, thereís a lot of knowledge on this forum, its great that you folks are willing to share.
Keep it coming
02-22-2009, 01:04 PM
Mike; i knew you had a tracer mill. I was suggesting just using the power pack on it to pressurize a hydraulic cylinder on the follow rest.
02-23-2009, 12:25 PM
Mark Stratton has plans for this in his book, ""Tricks of the Trade: Custom Rifle Metalsmithing" Book by Mark Stratton
" I think is the title, I'll check tonight when I get home.
His solution is a traveling steady with three air driven pistons that take the vibration out of the cut without pushing the barrel around like a standard traveling steady with only two rest pads.
I've done a few tapered barrels from blanks on my old 12" Atlas, definitely not the first choice, but you use what you have. I used the tail stock set over to determine the taper and then used the steady rest for support, tapering about 6" at a time and then resetting the steady. I am only a hobbiest so time didn't count. Sure wouldn't want to make a living doing it this way.
02-25-2009, 09:58 PM
I've been running through the same thing with turning some 3" diameter stock for barrels to some Parrott rifles. My lathe starts chattering like a couple squirrels fightin' over a nut. I picked up on a tip from one of the guys that added a block of wood into the opposite side of his four position toolholder. I also switched over to a sharp HSS bit instead of a carbide. I actually rest a 2' chunk 1x4 on the compound and follow the cutter. (hey, I don't have a turret toolholder). These recomendations really tamed things down quite a bit for my barrel turning. I am not working a pre-prod environment, so I don't know if holding a chunk of wood against the barrel will work for you. The snubber block in the toolholder would allow you some freedom though. The block gets adjusted after each cut. I can dig up the thread in the third hand if you are interested in more info.
02-25-2009, 10:11 PM
I have only done two barrels with long tapers, both done between centers with the tailstock offset. Chatter was horrible.
I had a piece of lead about 2 lbs and I used a big hammer and a piece of rod to bash a dent in the lead about the diameter of the small end of the barrel.
I held the lead opposite the sharp HSS tool bit with my left hand and used the right hand to apply cutting oil.
The mass of the lead just flat killed any chatter. I was just blown away that I hit on an answer first try!!
I don't know how that would work with your 'production' needs but it seems that there might be a way to rig up an 'arm' with a chunk of lead and a light spring to hold it opposite the cutting tool????
02-25-2009, 11:00 PM
If I remember right Bob Brownell recommended taking a 2"x2"x24" piece of white oak and drilling a hole at one end to fit a bolt that screwed into a follower rest hole in the saddle. You applied pressure by hand on the back side of the barrel to kill the chatter. Gary P. Hansen
02-26-2009, 09:29 AM
Hey guys...Great ideas,
Gary...I esp like that idea of a 2 x 2 piece of oak...quick, simple, and cheap. Think I may give that a shot.
02-26-2009, 11:50 AM
Now just make sure that you come back and tell us how things worked out, hear??
02-26-2009, 05:04 PM
If you could leave extra holding stock on the chamber end of the barrel you can hold the work piece in bored soft jaws more secure and thus deaden the part some or just leave the whole bar attached like with a bar feed.. We used to use lead shot in a bag or holder of sorts to dampen vibration on parts being machined, similar to this there was a boring bar made called a "devibar?" that had lead shot inside of it. When we made M-16 on a Monarch we had 2 hydraulic follower rests to take care of spring and chatter. No sanding or grinding involved.
03-04-2009, 08:03 PM
A taper-steady? 3 points of contact, 2 pads or rollers and 1 cutting tool. They all scissor in an iris formation based on a taper attachment. It would take some math and some fine adjustment on the pads or rollers, but it could be done. Think Hoberman sphere but in 2D. The body of the steady taper would maintain alignment, the moving parts would just set the radial distances. As long as everything is connected to form a closed circle, errors should average out. There could be as many pads as needed, they just need to be adjusted to converge on the tool as it approaches the center.
03-06-2009, 10:25 AM
Thanks for the input... I think I get it, took several cups of coffee and a couple of stubby crayons.
03-10-2009, 01:02 PM
What we would do in the various jobbing shops I have worked in would be to turn your barrel one half at the required taper, flip it and turn the other half, blending with the last cut of the first taper. Not really difficult at all but does require exact indicating of all machined surfaces. We have used soft jaws in chuck bored out to whatever taper is on your blueprint and using an adjustable 4 jaw chuck to indicate the SPOTTED unturned portion of barrel. Try this. It does take patience indicating from chuck to tailstock and back again but it produces a beautiful job. I know you can do this!
04-02-2009, 09:50 AM
Don't know if you have found a remedy but I'm going to run into a similar problem soon and came up with this, might work. Imagine if you could find a big enough blob of steel for the base it wouldn't even need fastening to the cross slide. I'm guessing deflection would be measured in tenth's and depend on diameter of work. Sliding the base in and out should take care of getting close to dead centre per pass but even this would change as it followed taper. Don't know how critical this would be, maybe someone else here knows or even if this would work. When I get around to making it will let you know, think the trick will be getting the right combination of pivot length and weight. If it were used regularly maybe a screw adjustment (40tpi) would be justified as well to counter depth of cut.
11-09-2009, 08:37 PM
hey i dont know if any one has solved this problem satisfactorly but i will give my 2 cents.. i hve taken lead as mentioned before and used it sucessfully on barrels just keep it lubricated got this idea yrs ago just by thinking lead dont sing out like most metals when dropped on the floor just figured it would stop the lathe from singing too.... and another i have found that your relief angle cut on your tools does make a difference (yes i still hand grind)
11-09-2009, 09:00 PM
I am envisioning something like a plunger..and as Jim suggested a valve spring..and then maybe a roller blade wheel on center with the barrel... Or perhaps a pair of roller blade wheels with the barrel 'v blocked' if you will..between them...
A person just has to kill the harmonic..and a poly wheel might just do that.
I know what you are struggling with... and I kill the chatter with a 2x2 hard wood stick. I would like a more professional solution for my barrel turning.
11-09-2009, 10:09 PM
Another thought would be to incorporate firm but compressible rubber rollers into the follower rest. Rubber is an excellent anti-vibration material.
11-11-2009, 11:08 PM
Wood was mentioned in the four sided tool post. Brass is better. This suggestion is in one of Brownells tricks of the trade books. You machine the first four inches of taper and then put the square brass rod in the 4 sided tool holder (opposite the cutting tool) and put a light contact pressure against the barrell and tighten things down. This spacing and material will significantly help to dampen the harmonics. At the gunsmithing course at Trinidad CO. several years ago a couple of students were fighting this problem and they were using a lead bar bent and draped over the barrell. One of the guys on this forum posted a thread on grinding a HSS finishing tool something like that might be a help. The other side of that coin so to speak would be to take a cut with a tool with a sharp point and very little lead angle. If you look at the cutting force vectors you want to minimize the force in the direction perpendicular to the turning axis. That is the direction that causes vibration. The column strength of the barrell is not a significant part of the problem. It is able to support the cutting force in that direction. Just some fodder for thought. Keep us posted on your progress.
Quetico Bobs Recommendation looks like the best prospect that I have seen short of a full blown Hydraulic follower.
11-12-2009, 08:25 PM
a spring loaded live center such as made by Co centric tool helps quite a bit. A local barrel maker uses a follower rest type tool with a bar of lead that hangs off of it pendulum style against the barrel as the taper is cut.
11-13-2009, 09:29 PM
Ridgid pipe die,the quick acting kind fitted with an old set of chasers re-ground to do the cutting.Only tie the quick acting lever to the taper attachment slide independant of the carrage.The carrage would traverse the length of the barrel on center while the die head did the taper following.With four cutters surrounding the work it shouldn't be able to chatter.
11-25-2009, 12:07 PM
Hard Urethane roller like a skateboard wheel would work? Would spread the load over more barrel area. Spring loaded and adjustable screw for spring pressure adjustment would be nice so you can turn down rhe pressure to minimumn required to eliminate chatter. Filling barrel with cerro safe to alter harmonics and simply heating and letting it run out later fior re use. Just my 1 cent worth,. Mike
12-06-2009, 08:48 AM
How about a pc of something soft with a hex in the center, and the same OD as a bearing? You could slid the hex down the barrel until it's snug, then your steady rest would tighten up against the bearing? Just a thought.
01-26-2010, 11:53 AM
You have almost got the answer, but a bit turned about!
Maybe 30 years ago I was asked if I could profile turn long bars of Spring steel, as used in Auto. Springs. They ranged in length from maybe 7 feet up to about 10 feet long, with diameters between 7/16" to about 13/16."
Much care and safety needed here!
They were turned on each end, or one end, varying lengths from 24 to 50"
The first say 9" approx was parallel and say between .3" and .5", which then was uniformly tapered around 16 to 38" up to full diameter, to a certain overall length. We needed to keep the result to within about .7" or so of specified design length
The solution was to build a special "Angle Plate" steady from some small offcuts of 3/4" Aluminium, (This is how we spell it in AUSTRALIA!)Tooling Plate. This was bolted to a slotted Tooling block which attached to the cross slide of my Colchester Triumph 2000 Lathe 71/2" x50", with Hydraulic Copy Turning Slide fitted. The slide is ground flat and has dovetail grooves, along its length. Very useful, that feature!
The vertical plate was bored at center height about 7/8"diam, and three 1/2" equal spaced holes bored on a larger PCD , which received eccentric stub axles, which have ball races of about 1 1/8 x5/16 x12" dble shielded. These are adjustable over about 5/16" diameter range, and are locked by an end fitted 1/4" x1/2" or so bolt and washer.
The OD of your blanks will need to be ground parallel to a uniform diameter, or turned if you can hold it tight. You will need to reference the OD to the BORE, and work out how to drive it. Threaded adapter or a face driver center? The LEADING steady is adjusted, close to the chuck end, and just nip the adjusters up to be a nice firm fit. The cross slide MUST NOT be moved once the steady is adjusted. That is what makes a Hydraulic Copy Slide so fabulous!! They really are the next best thing to CNC.
It would be useful to have a Rockwell C or or a Brinell hardness test done, or ask the supplier of the blank barrel. This will guide you in selecting the Speed envelope. The Speed / Feed envelope is very important in achieving good results.
You may need to experiment on a couple of reject barrels, prior to machining, to get a feel for speeds etc. It is really trial and error, but you will get better results at speeds over 600 RPM.
You next will need to set either a good precision Straightedge, on the template holder of the copy slide, or a centered ground bar of decent size, ?1" Silver steel bar mounted between centers and just track it along while noting the change in RADIUS. Major Diam. minus the Minor Diam and divide by two. over the length needed.
Now for the GOOD news! You MUST do this job in ONE PASS ONLY! Use a GOOD carbide tip that is precision ground with maybe .010 .015 nose radius and a good top rake ground into it with approach angle 90 degrees. You need to use an insert tip which is precision ground , and has a sharp cutting edge. Use a fairly hard finishing grade. Set it carefully on center height. From memory, I used to run my bars at fairly fast speeds, ranging from 750 to 1150 RPM. The tool is set within say 1/4" of the ball races. Needs a bit of clearance to allow the swarf to get away. The ideal is a tightly curled coil which may need to be clipped suitable set of diag cutters, every so often. It is preferable NOT to stop the spindle. If you do, withdraw the tool first.
Feed-rates used are important and were in the .005 to .010 IPR. At the max diameter, the depth of cut is getting quite small, and the finish can degrade if the feed rate is too fine.
Run WET with plenty of good coolant, and you will be delighted with the surface finish!I had no problem, while running, in lightly running my wet fingers over the bars. Get to know the process before trying this, it could be painful!
Use a live center in the tail-stock. CHECK every step twice. I had to be careful to have special outrigger support stands to stop whip, at the free end, and WITH no way of coming undone, or the result would have been a disaster! My machined end was secured using a loose oversize bush in a drill chuck, which had a little bit of clearance. On long bars, we slid the fixed steady with roller pads along the bar, following the cut, to prevent any possible excessive resonance type whip, as well as the tail-stock bush. This could be a lethal process if you fail to take all needed precautions. You are OK though as the barrel is short and supported at each end.
I got excellent results from this method, and the batch sizes were only small.
From around six, to sometimes fifteen of any size. The changeover times between batches was around three quarters of an hour, including the calculations, and setting the two straight edges. Vibration was rarely a problem,except for bars which had a rather deep depth of cut. The tips I used were KOMET unisix. These days all the suppliers have tips that will do the job. It may seem tedious and complex, but there aren't any short cuts!
At least, if you are using 4140 or similar, in the heat treated area, it machines very well at the higher speeds. I have turned maybe 1000
of these test springs, which give a variable rate with deflection, when coiled, and were only used in the test lab, prior to production, or on some Race cars.
By the way, this is my 51St. year in toolmaking and precision machining.
Hope I have given you some food for thought. Your web photos are fabulous.
01-26-2010, 12:13 PM
Thanks for the input
02-01-2010, 07:03 AM
Found an interesting reprint the other night.
MAKING RIFLE BARRELS.
From Machinery's Industrial Secrets. Reprinted by Lindsay Publications Inc.
2002 - ISBN 1-55918-280-6987654321 It is from Machinery Magazine
May 25 1916 About 64 pages, with numerous photos, and drawings.
YES, it is rather ancient, but sometimes Grandads approach works rather well.
The series of topics are based on the 0.303 Lee Enfield Barrel, and includes some detailed info on gun drilling, rifling, "Browning", which is the Blueinye a hammer. Even turning the blank is likely to cause some movement in the barrel. I am not sure, but possible, I picked it up from one of the vendors on E BAY. Another interesting contact is a nice gent in Vancouver "Guy Lautard"
He has written a number of great books for the home shop machinist etc. and a number relating to matters gunsmithing etc. His "Bedside Readers (3 of them,) are a really useful set if hints tips and ideas, on all manner of topics. He has a number of others including a couple of shooting related novels, which also have numerous good tips in them. Also has a VIDEO and instructions on making a rifling machine and demonstrates how to do it!
He does have a web site, but google it. I visited him in 1997 when I spent several days there, before going to Seattle for an SME conference. You will enjoy all his books, I sure do.
02-06-2010, 12:49 PM
Not a barrel, but at my last job I did a LOT of repair work to obsolete machiniery. I regularly had to turn a slight taper on a 24"x.500 rod for a webbed paper machine. Chatter was a real problem, and I spent a great deal of time working and reworking it until I got it right. Then on the ride home one night, I came up with an idea to build a tension device for the follower.
I built one using a rollerblade wheel and a gas strut from the rear hatch of a Metro. The polyurethane wheel combined with the gas spring effect dampened all the vibes and it really smoothed out the cut.
Sorry no pics. I left that follower when I left the company.
02-08-2010, 09:02 PM
Have you tried a brass or lead damper, hung accros the area of the cut? craig
03-03-2010, 05:07 PM
Isn't this a funny problem!
I ran into a thread over on the br forums addressing this very topic last month. It seems the consensus over there is to use a specific tool shape, DOC, and feed rate. I've tried it recently, with good success profiling blanks from 1.200 to .730 in some areas. The tool is a HSSCo, with a chip breaker ground in very close to the cutting edge. I did mine with a dremmel mounted cut-off wheel. DOC is only about .020, IPR .007, 360 RPM on a 1.00 piece, slower as it drops down. It takes a while, but defiantly removes all the drama and reduces the chip danger from 416 or LW (long, stringy, razor like).
You can find the thread here:
One thing I have done though, is stop profiling the entire blank between centers. I now chuck up only half at a time, but my profiles are all straight for the most part. I know one of the BR guys is using a steady mounted in the center, then blending the two sides. All of the finishing is done using a barrel spinner against wheels or paper.
I started out using positive rake carbide with a very small nose radius. It's a pain to deal with. Cut is good, but the chip gets my heart rate flowing like airborne school.
03-07-2010, 08:57 AM
I wonder how a tool post grinder would work for tapering a barrel? :confused:
03-09-2010, 04:22 PM
Grinding is a high force operation. If you use a regular wheel, you will still get chatter in the middle from tool pressure. If you use a skinny wheel, maybe 1/8 inch wide, you may get away with it.
03-16-2010, 04:12 PM
Let me preface this by saying that I have zero experience tapering barrels...
that being said what came to my mind first was to in stall a follower that was connected to a stepper motor, and translate the travel into the required number of steps. Unless you have all those skills that may not be very practical. You could, however, create a threaded follower and a small gear train to rotate the thread based on travel of the carriage. A rack and pinion or a gear train and a steel cable anchored at the head stock and end of the bed driving the follower...
03-17-2010, 10:02 AM
iornmonger...with all due respect... What??? You have lost me...sounds like you are talking about a power feed, which my late already has.
03-18-2010, 12:37 PM
I assumed that the taper is most likely being cut by offsetting the tail stock. Prior to a cut the barrel is displaced in the Y axis of the lathe. Since the cutting tool in this case follows a constant y axis displacement for each cut, the follow rest must be constantly adjusted to compensate for the metal that was removed. The follow rest needs to track the new profile, not the cutting tool, and that requires feedback. If a follow rest is mounted fixed in the y axis of the lathe and you attempt to cut a taper the follow rest will not, of course stay in contact with the barrel. If the follow rest was attached to the carriage, and it's distance from center was constantly adjusted in the y axis to compensate for the y axis change in diameter of the barrel, it would continue to support the barrel as the the taper is cut. The stepper motor was cited as a possible method of adjusting the follow rest continuously in a non mechanical means. If the tracking follow rest was mechanical, it would still have to track to match the taper being cut.
03-19-2010, 11:35 PM
what we did is use a follower rest with a primary tool bit to finish turn the barrel before the follower rest rollers contacted the barrel then the hydraulic taper attachment would finish the barrel. A lathe that I converted for the co. would take a 22 caliber blank 26" long the rough stock was 1 1/4" OD when the customer came to test the machine I became very scared, flood coolant, primary DOC .050" per side then the tracer, then one pass to finish, 20 HP, 1,200 RPM, 48 seconds, did I tell you I was scared, the customer was so happy I thought they were going to pee them selves. The follower rest was independent of the tracer slide. TJM$.02W :D
05-01-2010, 03:28 PM
I haven't turned any barrels yet but in other long and/or tubing work, I've used ... don't laugh ... a sawed off chip brush to both apply oil and dampen vibration when pressed mildly behind and just above the cut.
That said, lead dampens real well as mentioned and so probably would wood. Another thought might be to try a small patch of old carpet bearing cutting oil. It will dampen and lube at the same time.
Just one other thought, how about filling the barrel with the smallest gauge shot you can get and corking the ends. That might work well although it may not have enough "local" mass near the cut. In some other cases, I've tightly wrapped old lead solder around a part or spiraled it into an ID on tubular parts, but obviously this doesn't help much with a continuous length to cut.
05-04-2010, 07:08 AM
I tapered a 34 in 1.25 dia blank. I started out with carbide inserts while they worked well at both ends the center did suffer from chatter.
I switched over to a hand ground HSS tool with a slight negative rake.
.025 cut depth and 140 rpm with. 007 ipr.