Hi all,

I would like to know how folks go about cutting the radius from the straight contour of the chamber/breech cylinder down to the primary taper of a barrel. I thwant to do this to a barrel on a rifle I am currently building. I think I have a clue on how to do it. First I would cut some steps from the chamber/breech cylinder down to the primary taper. The blend them in with a half round file. My question is when I have the barrels in between centers should have the tailstock offset to match the primary taper or just leave the tailstock in-line? I know that there are better ways to do this with the making of a fixture (I have the plans for). But my access time is limited to the machine's and am looking for a down and dirty quick way to get it done.


Thanks! Chris

From he following post: Update 3-25-08 Shane Thompson Mini Mauser. PART 3 BARREL CONTOUR!!!!

This what I am asking about going from this:



to this:


My question is do I need to offset for taper or can this cut be made between centers?

The cut has to be made with the barrel straight between centers. If you have it offset, it will cut the steps offset, and they won't meet the two end sections right.

The reason you offset to do the taper is so that you can cut the taper while the carriage feed is going straight.

Since you're cutting the taper (radius) by stepping, no reason to offset.

dave

When I use to do this stuff we had a very expensive radii cutter.
My current lath has a tapper attachment so cutting the tapper is easy. Cutting the radius is a problem. What I can do is set up the barrel in my harrig head with a center support in the bore. I can program the radius in the mill and spin the barrel to cut the contour. Put the barrel back in the lathe and polish it out.

I use to watched Dennis Bellm over at P.O. Ackley's Custom Rifle Barrel Shop hand feed a standard r/h carbide cutter with the cross slide, and with the carriage moving at high speed, resulting in a beautiful radius. After which he would offset the tail stock, attach the pneumatic follower rest, and finish the job. It takes a lot of practice and guts to try that free hand on a customers barrel. Practice, practice, practice!

quote:

Originally posted by Westpac:
I use to watched Dennis Bellm over at P.O. Ackley's Custom Rifle Barrel Shop hand feed a standard r/h carbide cutter with the cross slide, and with the carriage moving at high speed, resulting in a beautiful radius. After which he would offset the tail stock, attach the pneumatic follower rest, and finish the job. It takes a lot of practice and guts to try that free hand on a customers barrel. Practice, practice, practice!

The larger the tool nose radius the easier this is to do and the less risky. If you use a really large radius the setup needs to be rigid.

Mark Stratton had an ingenious tool post attachment at Trinidad. I believe it is in his gunsmith tooling book as well.

I have a couple different methods I have used. Initially I would step the barrel to something similar of what I wanted the radius to be. Hand cut the radius manually, then file to final fit.

Now I use a radii tool similar to what kcstott mentioned, though mine was not very expensive. I can do convex and concave radii with quite a range. You need a decent size lathe to run them though...

OR, you could buy a CNC lathe Kidding, some machine shops will take on piece jobs if they are slow and you are not a pain in the butt. doughnuts or beer are always good bribes.

I have made a tool like the one in Strattons book and it works well. I have been putting an elipse on mine recently and the step cut and file is the only way to do it short of a cnc and it works good to. I like to make more cuts and file less so the shape you are going for is maintained better and obviously less file work...make the machine do the work!

I have also sent my elipse drawing to kreiger and had them cnc profile a new barrel.