Chambering, preference?

shortmag · Jul 26, 2006

How do you prefer to chamber, between centers? through head stock? or ? I am setting up my Nardini for chambering with a Flush system. I would like to here all the input I can before I order my chambering tooling.

Thank you

cheechako · Jul 26, 2006

short

Everyone has their own favorite method. I prefer to thread with the muzzle end in a four jaw and the breech end centered, supported near the breech with a steady rest. I then remove the tailstock and do the breech and chamber on the steady rest. My reason - once I get everything set up and in line I do not like to take the barrel out of the chuck until everything is done. And I feel that the longer distance between muzzle support and breech support the better. JMHO

Ray

Rustystud · Jul 26, 2006

Shortmag:

I think you have to have the flexability to do it either way. I prefer the headstock and a cathead.

I have a hollow center mounted on a piece of 3/8 black pipe for center to center work. I use a piece of heater hose and a duff norton coupler for through the headstock.

Rustystud

shortmag · Jul 26, 2006

Well I just made the first dumb mistake of my life, I wish! Just measured my headstock, I would have to be working with 28" and longer barrels to work thru the headstock. So my only option is between centers. Would you suggest using bushed center cutters or is there a better way to dial in using a steady rest? I reviewed the post with shop made center rest with a bearing, looks like it would be much easer to dial in with range rods and a last word indicator.

wesg · Jul 26, 2006

You can make a sleeve with 2 pairs of 4 setscrews to allow dialing in in a steady rest. Indicate the OD of it with the barrel between centers and then fine tune by indicating the bore.

Or, make an internal center for the spindle. I just did one for my Graziano. I threaded a heavy sleeve to fit the tail end of the spindle and bored it for a piece of hollow Thomson shaft with a center threaded in the end. It'll eventually be used with a flushing system, or I could have used a solid shaft and ground the tip.

Or more elaborate, several years ago I made one for a big Monarch that has an inside out 4 jaw chuck on the end so I can true it up in concert with a cathead on the spindle.

Flapjack Frank · Jul 27, 2006

Shortmag

Doing any work on the lathe is more accurate when done using a steady rest. Keep the working end as far away form the chuck as possible.

As for dialing it in on the steady reast, good luck, I have never found this easy, but most machinist have no trouble with it.

Kurt Westfall · Jul 27, 2006

? Why do you( Ray and Flapjack ) feel that farther away from the chuck is better? Not trying to start a fight, just woundering. To me it would seam that the closer to the chuck the better as it would be a more ridged setup.

Zebra13 · Jul 27, 2006

Gentlemen,

Speaking of chambering in a lathe with a big headstock, I thought I saw, on this forum, a drawing of a device (center, sleeve, etc.) somebody had posted that fit up to the outboard side and into one's spindle so you could chamber "through the headstock" despite the headstock being to big to pass a barrel all the way through. Sound familiar? It might have been a drawing from John Hinnant as it looked similar to his stuff. I am unable to "re-find" the post. If anybody out there has it and wants to re-post, or knows where I can find it, I would appreciate it.

Thanks,
Justin

Flapjack Frank · Jul 27, 2006

Kurt,

Good question, I do not suppose I have ever had anyone ask me "why" the distance is important.

I see two reasons. First, the ways are usually in better condition the further away from the chuck you get. Most machining is done right at the chuck, and that is where all the use of the ways is at as well. Ware and tear will be more pronounced there.

Second, if you have just a little "slop" or movement in the headstock, or if you use a three jaw chuck that is not exactly centered (which most are not) by moving away from it and using a steady rest you remove this out of round movement from the part being turned.

The combination of the two are devistating for something that is in need of every bit of accuracy you can muster.

Thanks again for the good question, and I am not worried about starting a fight, you cannot hit me to hard trom this distance.

Flapjack Frank

cheechako · Jul 27, 2006

Why do you( Ray and Flapjack ) feel that farther away from the chuck is better?

Kurt

I think it's called geomertry, or at least one of those math subjects that we should have paid more attention to.

A perfectly aligned barrel would be one whose exact center at the muzzle end is aligned with the exact center of the breech end. So, when aligning said barrel, the farther apart your two data points are the more accurate the alignment. Am I wrong??

Ray

Kurt Westfall · Jul 27, 2006

Fair enough. Geomertry? Don't think that was taught back in my school dazes.

Clemson · Jul 27, 2006

Let's assume that the muzzle of a 22" barrel is chucked up in a 3-jaw and measures a fairly sloppy .005" runnout. Twenty inches of barrel down the ways the steady holds the thing....well....steady. The two inches that stick out of the steady, where you want to do your chambering and threading, will have a max runnout of 2 / 20 * .005 = 0.0005"

I challenge anyone to mount a barrel in a 4-jaw through the headstock and do much better than that! For a hunting rifle, it just isn't necessary. I use a collet to hold the muzzle. Runnout is more like a max of 0.001 at the muzzle. The chamber end is held in the steady rest, and you can do the math yourself.

Clemson

Ken R Catskin · Jul 27, 2006

Zebra - your not talking that napkin drawing I did are you?

http://tumalo.org/catskin/BarrelJig.pdf

Still haven't built that to test it out, it would need a coupler and such for the flushing sysem too.

Ken

geomertry - huh?

zero · Jul 27, 2006

cut the threads between centers..
put the stedy rest close to the chamber end of the barrel.. that will give you a rigid
setup to cut the chamber as true to the bore as posible(you may need to take a very ight clean up cut on the barrell od befor any work on the barrel begins..)..

shortmag · Jul 27, 2006

Thank you all! I realy appreciate all the advise.

Zebra13 · Jul 28, 2006

Ken,
I don't know...I can't get my $%!@#* computer to pull up the drawing! I will keep trying!

Thanks,
Justin

J. Randall · Jul 28, 2006

Frank, I have to respectfully disagree. If you have enough slop in the headstock to cause problems it should be addressed before you start the gunwork. If you have a 3jaw with an out of round condition, either shim it till it runs true, or put the 4 jaw on and dial it in dead nuts[my prefernce]. It would have to have a bunch of wear on the carriage ways to cause any measurable taper on about and Inch of shank and threads. Also you are pushing the reamer with the tailstock ways, and they are generally in good shape up near the chuck. This may sound crude but I have seen it done many times, on a lathe with a long headstock, build a doughnout out near the muzzle end of the barrel by carefully wrapping it with masking tape till it will just barely slip through the spindle,this suppports the outer end quite well. then chuck the breech end just as close to the chuck as you can comfortably do your turning,threading and chambering all in one shot. I have seen enough of these done this way that will shoot one hole groups at a 100yds and 4inch groups out to 800 yards to make a believer out of me. James

ulav8r · Jul 28, 2006

Don't use a chuck.

At the Colorado School of Trades in the mid-70's we used 9 inch South Bends and got very good results with a dead center in the head stock. The barrel blank had centers cut with a piloted center cutter to get the centers concentric with the bore. The barrel was then turned between centers to get the rear cylinder and thread stub concentric. Threads were cut between centers and then set up for chambering.

The drive plate was unscrewed from the spindle at least one full turn. The dog on the muzzle was lashed to the drive plate and the plate tightend to hold the barrel tight to the center. the cylinder was then centered in a steady rest. The rest was set just behind the threads on the cylinder that had been turned between centers and polished.

This may be somewhat slower than using a chuck and working through the headstock, but it will give good results with most any lathe that that is long enough for the barrel and has decent spindle bearings. Working through the headstock is more dependant on the quality of the spindle bearings and adjustment of the jaws for runout.

cheechako · Jul 28, 2006

shortmag

A lot will depend on whether you are working on a a finished barrel or a new blank. Finished barrels, if they are blued, are tough to work with a steady rest because you cannot put the rest anywhere that the bluing might be rubbed off. So they generally are best done through the headstock with a spider or whatever other means you might choose to use to keep it in line.

Barrel blanks are a different cat. What I do is first run in a 60 degree piloted center reamer to freshen the centers used during the turning or grinding of the blank. Then I spin the blank between centers and with a dial indicator check the concentricity of the outside. If it's nuts dead on, good. If not I take a light cut at both ends, maybe and inch or two long so that I have two cylindrical points to indicate on. The one on the muzzle end will be removed when I take the required inch or two off the muzzle and the one on the breech will be removed during threading. The main thing is you now have two perfect indicating points on the barrel. How you go from there (thru the headstock or on the steady) is up to you.

wesg · Jul 28, 2006

Ken,

How are you going to true that up? Eyeball through the bore?

Chambering, preference?

Plastic

Cast Iron

Rustystud

Guest

Plastic

Titanium

Plastic

Stainless

Plastic

Plastic

Cast Iron

Stainless

Aluminum

Aluminum

Aluminum

Plastic

Plastic

Stainless

Cast Iron

Cast Iron

Titanium

Similar threads