Thread Dies

[BUSTINDOGS]

I want to put a new barrel on a vanguard action which is a metric thread. I had the bright idea of using a thread die instead of changing the gears in the lathe to cut metric threads and going through the process of cutting metric threads. I plan to make a fixture to hold the die so I can start it straight and turn a nice little run-in feature on the barrel to also aid in starting it straight. Anyone done something like this before? I have used dies before, but never one this large.

 

[sable tireur]

With all the firearms forums on the web, don't you think this would have made the headlines by now?

There are lots of conversations about this process and how it could be made to work but so far...nothing.

Threading on your lathe usually implies that you have already established perpendicularity and concentricity. Adding another fixture and the die to this mix will create some unnecessary problems.

Check out some of the other conversations to gain the deeper understanding of this quest.

 

[tobnpr]

Adding another fixture and the die to this mix will create some unnecessary problems.

This.
There's no such thing as a tailstock on an engine lathe that's perfectly aligned radially and axially to the spindle centerline- which is why we use floating holders for most reaming and tapping second ops on a lathe.

That said...
It is possible to use a rigid setup for chamber reaming, so I suppose that concept could be adapted if you were dead-set on doing it for a die holder.
The reaming setup (seen it, not done it) requires a tooling block that's rigidly attached to the cross-slide, and is bored in-place with a cutter(s) in the headstock/spindle. End result can't be anything but perfectly true to the spindle axis. Using that hole as a holder for your die fixture (assuming the die fixture you fabricate is also true) could yield "acceptable" results I suspect- but it's a s***-ton of work for a one-off.

Personally (as I'm missing some change gears for my Sheldon), I'd just get a prefit and be done with it.

 

[Taylorbok]

I'm sure it would/ could work but as mentioned gonna be a fair bit of work to get it set up to produce good results, it should be quicker for you to swap the gears in the lathe.

 

[BUSTINDOGS]

I guess I'll change the gears and do it the right way... My thinking is if the gun doesn't shoot I'll be cussing that thread die for years.