Greg,As far as tooling goes, I'm pretty sure you'd be able to find a bigger double chamfer kinematic mount insert that would work to cut that thread. You'd probably need to find the next narrowest insert and take two passes with an axial shift to get the right form width. That would avoid the need for custom tooling at the expense of a little longer cycle time.
Photo of similar size "drill rod" with a size 12 for scale.Hi again Bob:
I believe the first thing to do is to establish just what this thread is supposed to do.
If it has to mate with something, that's a very different proposition than if it's just going to be filled with grout.
Finding that out decides if this is even going to be a workable strategy or if it's just hopeless.
So before you get too deep into this...find that out.
The trial I proposed with a single or two flute home made boring bar is a good and cheap way to do that.
Actually about 2.25" overall depth for the thread.This sure looks like the kind of job that could kick your ass if you're not sure what you're doing.
You're planning to threadmill with a 1.5" T-slot cutter or woodruff type cutter 4" down in a 1.84" bore in steel with a Cat40 machine? That's a hell of a lot of cutter engagement with a big stick out on a lightweight machine. Sure it's possible, but not economically. Are you going to take 20 passes each part?
I'd recommend you go buy yourself a good cnc lathe.
Mills don't make very good lathes and you need a good lathe for this job.