Thanks PJs
I machined the 9/16" hex broach to .585" across the flats of the hex, after hardening it was set up in the tilting dividing fixture and ground to .570" across the flats which gave some wiggle room on the hex of the vises screw and allowed for a couple of sharpening's, it's also ground at a 3° taper to allow for the 1° wobble in the broaching tool and to give the cutter some side clearance as it passes through the hole.
It works very well, here is a photo of the grinding process on the 9/16" broach
Thanks PJs
Doug
Attachment 24897