How do you turn a barrel with out chatter?

triumph406 · Jun 30, 2022

thermite said:
Meahhh.... my view is one learns to turn steel looooong before stepping up to doing anything much atall with tube artillery, any bore-size.

Along the way, dealing with the chatter & vibration issues are meant to be learnt, understood, and well-enough to become a comfort, not a barrier. "In the metal". Hands-on. Not "on Tee Vee"

ELSE NOT.

Profiling a barrel FIRST, learning general lathe turning, tooling, set-ups, and compensations for marginal equipment LATER has poor odds of a good outcome, regardless.

VERY poor!

Agreed, if turning a barrel causes chatter, and the OP doesn't know why, then there's going to numerous other challenges for the OP
How to turn a thread for a suppressor?
How to ream the chamber?

hopefully it's his own barrel and not a customers.

---------------------------------------------------

If I had to do a lot of barrels, I'd rough the OD, and send it out for centerless grinding, sounds expensive, but the guy I used to use for centerless grinding was rediculously cheap. Couldn't hold a tolerance when required, but the price was right.

triumph406 · Jul 1, 2022

thermite said:
No need to be a "gunsmith" to be aware. Most anyone with eyes or even only a functioning sense of TOUCH is generally aware that "bang-stick" barrels are almost NEVER purely "right-circular cylinder" shapes, end to end.

There is nearly ALWAYS a "profile" of some sort.

Old Skewl octagonal barrel, BTW, was finished by hand draw-filing. Lathe chatter - nor any lathe at all - not really a factor. See also the earliest form of "Damascus" barrel technique, fintional, not just decorative.

Not entirely true, I shoot NRL22 (22LR) and would say 95% of rifles have bull barrels of constant diameter. Small sample size of course.

michiganbuck · Jul 1, 2022

Wow, almost $400 for a ww1 98 barrel.

I used to turn ww2 98barrels ODs with HSS tool bits with zero chatter.
I think sharpness and proper rake angles are key to no Chatter turning.

Mauser Gewehr 98 Barrel | World War 1 | 8mm Mauser

You are considering a vintage Mauser Gewehr 98 Barrel -- It's chambered for 7.92x57mm Mauser ammunition. It's in good shape.

oldarmsofidaho.com

clarkmag · Jul 26, 2022

I have tapered a number of barrels this year.
My compound has 3.5" of travel. I set the compound to 0.22 degrees. There is not that much resolution or accuracy on the degree dial, so I dial the angle in with a dial indicator.

My little PM1236 lathe works best on cutting pounds of steel with positive rake and sharp carbide inserts made for Aluminum.

Keeping that 3.5 inch travel close to the chuck helps. The live center in the tailstock gets further and further away, until the taper angle changes to 3.5 degrees near the breech. The last 3.5" cut before the angle change is the worst for chatter.

Change spindle speeds, change cutting depth.

6 pounds of chips is a real mess.

SilveradoHauler · Aug 8, 2022

Air Follower Steady Rest

I have run across a couple of references to using what was termed an "air follower steady rest" on a manual machine when contouring rifle barrels. In the photos of the barrels I have seen it appears to work well but I have no idea what the rest actually looks like. They seem to be DIY projects...

www.hobby-machinist.com

I am gathering parts now to build a similar unit. I have most everything except for the air cylinders.

Look at the photo carefully, there is a boring head in the tailstock used for offsetting the taper.

I have tapered a few M98 barrels to remove the steps, did not use any type of steady or follower. Correct tool geometry, feeds and speeds are the key, no chatter. P.O. Ackley explains this in one of his books. I have one of the barrels left, if I get around to it I will post a photo.

I also am building a tracer attachment for one of my lathes to simplify profiling barrels. Combined with the air follower this will make a nice barrel contouring machine.

NewGunPlumber · Aug 10, 2022

That's and interesting jig. Haven't seen one like that before but like the theory

steve-l · Aug 12, 2022

SilveradoHauler said:
Air Follower Steady Rest

I have run across a couple of references to using what was termed an "air follower steady rest" on a manual machine when contouring rifle barrels. In the photos of the barrels I have seen it appears to work well but I have no idea what the rest actually looks like. They seem to be DIY projects...

www.hobby-machinist.com

I am gathering parts now to build a similar unit. I have most everything except for the air cylinders.

Look at the photo carefully, there is a boring head in the tailstock used for offsetting the taper.

I have tapered a few M98 barrels to remove the steps, did not use any type of steady or follower. Correct tool geometry, feeds and speeds are the key, no chatter. P.O. Ackley explains this in one of his books. I have one of the barrels left, if I get around to it I will post a photo.

I also am building a tracer attachment for one of my lathes to simplify profiling barrels. Combined with the air follower this will make a nice barrel contouring machine.

Please show us the tailstock rig with the boring head. Have you used this rig yet? Mass is an effective deterrent to chatter. The pistons and brass heads appear a bit low in mass. How effective is this?

Freedommachine · Aug 16, 2022

clarkmag said:
I have tapered a number of barrels this year.
My compound has 3.5" of travel. I set the compound to 0.22 degrees. There is not that much resolution or accuracy on the degree dial, so I dial the angle in with a dial indicator.

My little PM1236 lathe works best on cutting pounds of steel with positive rake and sharp carbide inserts made for Aluminum.

Keeping that 3.5 inch travel close to the chuck helps. The live center in the tailstock gets further and further away, until the taper angle changes to 3.5 degrees near the breech. The last 3.5" cut before the angle change is the worst for chatter.

Change spindle speeds, change cutting depth.

6 pounds of chips is a real mess.

Is that a single flute endmill? I had never thought to use one on a lathe before, I'll have to try that.

clarkmag · Aug 16, 2022

Freedommachine said:
Is that a single flute endmill? I had never thought to use one on a lathe before, I'll have to try that.

Yes.

wyop · Aug 25, 2022

When I profile barrels, the rough cuts I do with a special tool at slow RPM's that cuts chips that are "6's and 9's". I'll take a pic of the tool I've ground for this job and post it tonight.

michiganbuck · Sep 19, 2022

I know a crackerjack is a kind of wheel dresser.
But something we also called a cracker jack was a vice-like / pliers-like device often made of wood that you would hanker down on the OD of a shaft (barrel) with a slip of abrasive between the jaws and the steel to be polished paper. starting out with 120 or what, and going down to whatever finish you like. The hand travel would be slow so it was like you were turning with a tool bit, travel was about tool bit speed. You would end up with a darn good-looking finish.
You could also tickle in an OD size with this method.
Getting a lot more pressure on the abrasive paper with little chance of locking a finder in the paper

50BMG DUDE · Oct 14, 2022

I've turned thousands of barrels, literally. I make many of the barrels sold in the gun kit building market (not AR's). I've done pencil AK barrels up to .50 BMG M2HB barrels. I've tried hydraulic steadies, pnuematic steadies, a new Okuma LB3000 w/ variable freq spindle speed, lead shot in the bore, rubber/lead bands like they use on brake drums. Best thing I've found wheather on a turning center, toolroom lathe or even on an old Southbend 14 is a DCMT holder taking about .030-.040 per pass, .01 per rev FR. running about 500 RPM (play with RPM depending on diameter). LAP your tailstock center hole! - Hold the spindle end in a chuck, collet, or we use a Schunk face driver. NO COOLANT

I'll bet I've made 50,000 lbs of chips turned off of barrel blanks this way.

YMMV

john.k · Oct 15, 2022

Traditionally barrels wernt turned ,but rolled to shape in barrel mills and finished by 'spinners'......a dangerous trade where if a 8ft grinding wheel didnt explode and get you,then the silica dust certainly would.

NewGunPlumber · Oct 17, 2022

50BMG DUDE said:
I've turned thousands of barrels, literally. I make many of the barrels sold in the gun kit building market (not AR's). I've done pencil AK barrels up to .50 BMG M2HB barrels. I've tried hydraulic steadies, pnuematic steadies, a new Okuma LB3000 w/ variable freq spindle speed, lead shot in the bore, rubber/lead bands like they use on brake drums. Best thing I've found wheather on a turning center, toolroom lathe or even on an old Southbend 14 is a DCMT holder taking about .030-.040 per pass, .01 per rev FR. running about 500 RPM (play with RPM depending on diameter). LAP your tailstock center hole! - Hold the spindle end in a chuck, collet, or we use a Schunk face driver. NO COOLANT

I'll bet I've made 50,000 lbs of chips turned off of barrel blanks this way.

YMMV

What insert do you use?

kenton · Oct 17, 2022

NewGunPlumber said:
What insert do you use?

And what nose radius?

Nmbmxer · Oct 17, 2022

The couple of barrels I've done started as 1.25" blanks and I did the profile in steps, pulling a few inches of barrel out at a time and finished with a pneumatic belt sander to blend the steps. That finishing sander would hog off material with a coarse belt.

220swift · Oct 17, 2022

50bmgDude
Any pictures ?
Do you set your cutting edge on center?
Thanks for posting helpful info and sharing your knowledge.

Hal

50BMG DUDE · Oct 18, 2022

Using Kenametal DCMT3251LF KC5010Grade is my goto. The smaller the nose rad the less tool pressure. I tried to get VNMG to work for me but the negative geometry just makes for chatter.

Dead nutz on center height, no pics, never thought to take any. Next time I'm running barrels I'll grab some.

Another thing is if you do start to get chatter, stop it immediately, change your feed override up or Spindle RPM down. Once you have chatter in the blank you will not likely get it out on the lathe. I have saved a blank or two with a cheap porter cable belt sander and an 80 grit belt to get out any chatter.

john.k · Oct 18, 2022

Oddly enough ,the worst chatter imaginable is really good for the grinder ........the wheel loves the interrupted surface ,and grinds freely until the chatter is all ground out,then you have to tension all the steadies or you will get grinder chatter.

Nmbmxer · Oct 19, 2022

This is the kind of belt linisher we had for polishing turned parts:

2022-10-19 09_19_55-Dynabrade - 1-1_2 x 30_, 3,400 RPM Air Belt Sander - 61087755 - MSC Indust...png

How do you turn a barrel with out chatter?

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