"Shimming" barrel to fit lathe?

[LRShooting]

I have access to a pretty good sized lathe that I did some work on and got running today. Ill save you the trouble of explanation, but its not mine and I cant afford to put money into it. Especially since its a pre-1912 schumacher, boye, and emmes lathe. It has two chucks...one that auto centers and one that is a 4 jaw independently adjustable. The auto center is not perfectly aligned, but will hold the barrel, the 4 jaw is too wide and I dont think a large bull barrel would hardly be big enough, much less the thin one Im working on.

Can you shim barrels to fit them into lathe using pipes formed into collets? Or would I be better off just using the auto center 3 jaw chuck and itll be accurate enough? Im looking to crown the barrel. I figure a tactical crown would be nice and wouldn't require me to have the barrel concentric as compared to say an 11 degree taper. Ill finish the barrel crown with a ball bearing and lapping compound of some sort. Probably just auto polish. This isn't a high end rifle, but it definitely needs a new crown. *Cheap chinese barrel.*

 

[Howard Roark]

As an experiment either way is fine. The preferable method would be to perfectly align the bore in the four jaw using shims to make the barrel fit. The out of true three jaw will give you an off center rebated 90° crown but that is the beauty of a 90° crown. You can't screw it up like an off center 11°.

Either way, do not mess with the muzzle after you cut it with a sharp tool. Lapping muzzles is for cleaning up a file and hacksaw job because you don't have a lathe.

 

[Zeke/PA]

I have access to a pretty good sized lathe that I did some work on and got running today. Ill save you the trouble of explanation, but its not mine and I cant afford to put money into it. Especially since its a pre-1912 schumacher, boye, and emmes lathe. It has two chucks...one that auto centers and one that is a 4 jaw independently adjustable. The auto center is not perfectly aligned, but will hold the barrel, the 4 jaw is too wide and I dont think a large bull barrel would hardly be big enough, much less the thin one Im working on.

Can you shim barrels to fit them into lathe using pipes formed into collets? Or would I be better off just using the auto center 3 jaw chuck and itll be accurate enough? Im looking to crown the barrel. I figure a tactical crown would be nice and wouldn't require me to have the barrel concentric as compared to say an 11 degree taper. Ill finish the barrel crown with a ball bearing and lapping compound of some sort. Probably just auto polish. This isn't a high end rifle, but it definitely needs a new crown. *Cheap chinese barrel.*

"Shims" in a four jaw? What am I missing here?
Is the lathe equipped with a steady rest by chance?

 

[rcmodel]

If you have a four jaw chuck you don't need shims, unless the barrel is really really tapered.

What you do need is a tight fitting bore spud, (make one out of brass rod) and a dial indicator to center the bore in the four-jaw chuck.

Stick the muzzle through the chuck from the back, dial indicate the bore perfectly centered,
And have your way with whatever type of crown you care to cut.

rc

 

[Steve2md]

Turning between centers prior to facing the breech and bore is also an option. That will give you bore to barrel concentricity in the easiest manner, though to turn between centers, you'll need to take much lighter cuts to keep from bringing the barrel to a halt.

 

[rcmodel]

I thought I thought all he is wanting to do is crown the muzzle of the barrel????

Maybe I read it wrong?

rc

 

[nettlle]

Can you chuck the 3 jaw in the 4 jaw and line the 3 jaw up that way?

 

[Steve2md]

RC, he did, I misread

 

[LRShooting]

If you have a four jaw chuck you don't need shims, unless the barrel is really really tapered.

What you do need is a tight fitting bore spud, (make one out of brass rod) and a dial indicator to center the bore in the four-jaw chuck.

Stick the muzzle through the chuck from the back, dial indicate the bore perfectly centered,
And have your way with whatever type of crown you care to cut.

rc

As a general reply to others as well, this is close to a 12 inch diameter chuck. The jaws are 1.5 to 2 inches wide with an arc radius of roughly 4 inches. That doesn't allOw them to tighten enough. It's a big lathe...I think Howard got it right. I don't know tho. I'm new to doing things properly . I need to sharpen the tools though, they are terrible dull and push work over through deflection rather than cutting. I'm gonna try to acquire a small south bend or atlas lathe this coming year. I'm still in college and trying to buy farms so ill see.

 

[Howard Roark]

I'd like to see the 4 jaw chuck that's too big to hold a barrel. The biggest that I've ever saw was a massive 4' 4 jaw that had a 2' 3 jaw on it for every day use. You don't see those very often.

 

[Blue68f100]

Some jaws can be flipped over for a different size. All depends on the jaw design. Allows for inside or outside grips of different ranges.

 

[Zeke/PA]

Is the barrel still attached to the action?
At any rate use at least 3 tapered wooden""shims" on the back end of the head stock to minimize the "whip" there.
Don't run the lathe at a high RPM.
Tools? I'm just guessing but it sounds like you're using Carbide stuff.
In all honesty, stick with High -Speed tools to end your headache as they can be sharpened on the average "home style" grinder.

 

[LRShooting]

Is the barrel still attached to the action?
At any rate use at least 3 tapered wooden""shims" on the back end of the head stock to minimize the "whip" there.
Don't run the lathe at a high RPM.
Tools? I'm just guessing but it sounds like you're using Carbide stuff.
In all honesty, stick with High -Speed tools to end your headache as they can be sharpened on the average "home style" grinder.

Yea...they aren't too expensive really for some that would do me well for what I need. I don't know what kind they are. I assume carbide because everything else is rusted bad and the cutting edge is grey and clean. I'm a little confused by the wooden shim thing though.

 

[LRShooting]

I'd like to see the 4 jaw chuck that's too big to hold a barrel. The biggest that I've ever saw was a massive 4' 4 jaw that had a 2' 3 jaw on it for every day use. You don't see those very often.

Ive never seen a lathe this big anywhere else either. Ill take some pictures when I can. Blue68 might take the cake. I don't know for sure what the jaw design is, but it'd sure be nice if I could just flip them. One of the chucks looks like it has "steps" on the outside that can be placed on the I.D. of pipe and opened to hold the work piece I'd its of that size.

 

[rcmodel]

Pretty sure if the chuck jaws have 'teeth' on the outside, they are reversible in the chuck, and will tighten to hold even the smallest work.

Before you take them out to reverse them, check to see if they are numbered to the chuck position, and put them back in the correct places.

The wooden wedges Zeke/PA is talking about go in the back of the tail stock hole to center the barrel where it comes out of the hole and the action is sticking out.

Without the wedges, the spinning action & barrel hanging out the back will be out of balance and try to flex & wiggle around when you spin it up.

Hope this helps.

rc

 

[Blue68f100]

We had a lathe at work that could handle a 25' long pipe and as large at 3'dia if I recall. It was a monster. There was 2 cranes set to service it. Working for an oil company we would end up turning some long drill pipe and some vessels were rather large in dia.

All of the lathes I've been around had jaws that were reversible. Hope your does..

 

[LRShooting]

Pretty sure if the chuck jaws have 'teeth' on the outside, they are reversible in the chuck, and will tighten to hold even the smallest work.

Before you take them out to reverse them, check to see if they are numbered to the chuck position, and put them back in the correct places.

The wooden wedges Zeke/PA is talking about go in the back of the tail stock hole to center the barrel where it comes out of the hole and the action is sticking out.

Without the wedges, the spinning action & barrel hanging out the back will be out of balance and try to flex & wiggle around when you spin it up.

Hope this helps.

rc

Oh, that makes since now. Im new to this, so I dont understand all the tricks yet. And these "teeth" are really just large steps. I think there is 3 steps, just like a stairs. They are rounded outwards, so flipping them around wouldn't really make since in this case. Its only the case with the 3 jaw auto center. I need to go look to see if the 4 jaw flips around. I sure hope it does...

 

[LRShooting]

We had a lathe at work that could handle a 25' long pipe and as large at 3'dia if I recall. It was a monster. There was 2 cranes set to service it. Working for an oil company we would end up turning some long drill pipe and some vessels were rather large in dia.

All of the lathes I've been around had jaws that were reversible. Hope your does..

Thats huge! I hope this one does too. Its not my lathe though...I dont know if I mentioned that in the post. Its my uncles, but he lives 6-7 hours away and I just tinker with it. We farm what land we haven't already bought from him sooo I have pretty well free range to use what ever is left there. Not much of interest except that lathe though...

 

[BBBBill]

Make a spider (piece of steel pipe or aluminum tube) large enough to be gripped by either chuck. Dial in/center as close as possible. Slip the barrel in, tighten the spider bolts, slip an alignment spud in the bore, and fine tune. Remove the spud and crown the barrel. You will still need to keep the speed slow and use the wedges on the back side to minimize barrel whip. Directions for making a spider can be found in various places on the web.

 

[rcmodel]

I sure hope it does..

Just based on 50 years experience with lathe chucks?

It does.

You looked at the big picture.
Not the fine details you had no idea what you were looking at..

Please excuse me for my blunt assessment of the lathe, and your view of it.

But, that's my story, and I'm sticking too it!.

rc

 

[dsm]

Here is the spider I made to do barrels on. The barrel is held in by 4 brass tipped 3/8-24 screws and there is a spider on the outboard side as well. Note: the action is screwed on to fit bolt nose clearance when I took the pic.

 

[dprice3844444]

check craigslist in Missouri
http://stlouis.craigslist.org/tls/4796301572.html
http://springfield.craigslist.org/tld/4788564448.html sold new in springfield
http://grizzly14-px.rtrk.ca/search?q=lathes

now if you could find a 10 or 11 inch delta,you could have something .most all the other lathes are 50's pre Korean war,ww2 era.are the spindles going to be in tolerance?are replacement parts like drive belts going to be available?
check out the grizzly lathes.you can go down to springfield to check them out.

 

[dubbleA]

I am with DSM. When doing anything on a barrel I prefer to run a spider on the outboard end along with a 4 jaw chuck or spider and coaxially indicate the barrel off the bore using a .0001" indicator. Doing so will make your chamber, crown, threads etc concentric and perpendicular to the bore. That's just the way I do it.

 

[Mr.510]

I'm not a gunsmith but I am a master craftsman machinist. With a big, old lathe like that here's what I'd do: Grab a piece of aluminum round stock the four jaw chuck can grip that's about an inch long. Bore a hole through it the barrel will slip-fit through. Saw cut through one wall making a "poor man's collet". Grab the barrel in the collet in the four jaw so that one jaw just misses the saw cut. Use a bushing or wood wedges as described above to center the action end that's hanging out the back of the headstock. Dial in the end of the barrel you're working on. I'd have this setup, dialed in, and be making barrel chips in 20 minutes.

 

[LRShooting]

Make a spider (piece of steel pipe or aluminum tube) large enough to be gripped by either chuck. Dial in/center as close as possible. Slip the barrel in, tighten the spider bolts, slip an alignment spud in the bore, and fine tune. Remove the spud and crown the barrel. You will still need to keep the speed slow and use the wedges on the back side to minimize barrel whip. Directions for making a spider can be found in various places on the web.

Good idea...Ill keep that in mind!