I would swear that I have seen round stock or regular mandrels to hold square stock and I can't relocate the items that I saw because I'm not using the right words to search on Google or elsewhere. Some time ago eBay had such a part to hold lathe bits for sharpening that were mounted in a square holder for setting the angle and I can't relocate those either. What I've got in mind is something to hold a 1/4 or 3/8 HSS tool bit with a set screw so it can be set to duplicate the same angle face when sharpening. It would have to work better than a newbie trying to do it by hand. Any leads??