There needs to be a key between the two vise tubes to keep the front jaw from rotating. The exterior one is easy to cut on the mill, the interior one not so easy. Adding to the problem is I have threads on one end so it needs to be blind. Sooo, even if I had a broach, it wouldn’t work.
[OxTool] Tom is going to cut a through slot in the outer tube and “make it one” by welding the tube to the base plate. For various reasons, I’m not so keen on that idea and hit on this one, from watching too many shaper videos, using the lathe to cut the keyway. So I got out my biggest boring bar (a whopping 3/4″), ground a square edge on a HSS blank, locked the spindle and started plunging. Took forever but worked well.