On Sun, 26 Apr 2015 21:18:02 +0000, MATHSMAN
wrote:

I need to cut a square hole through a stainless bolt, using it as a lathe
tool holder.I have drilled bolt no problem with Cobalt drills. Is it now
down to a lot of work with taper files or can I BROACH IT?

Here's what a guy on you tube did
https://www.youtube.com/watch?v=7n1r5XfVkyk