On 7 March 2018 at 04:05, Gene Heskett <ghesk...@shentel.net> wrote: > So the only way is to buy R8's with square bores,
I don't think that is the only way at all. You could make solid ER32 "collets" with grub screws in the end. (getting the extractor flange right would be a challenge). Bored true they would hold the tap true, with drive from the grub screws on the square. Needs one per tap size, but it's an easy CNC turning job. I recently (and accidentally) bought a pair of floating tap holders. There is no reason that those would not work for rigid tapping, and they add a bit of relaxation to the process in the event of a problem. Those take a DA collet and have a pair of grub-screws to grip the flat. ER collets specifically for tapping exist (with a square in the back) https://www.ebay.com/itm/Techniks-1-2-ER25-Rigid-Tap-Collet/122122673510 You could add a pair of drive grub-screws to a standard round R8 collet. You might need to soften it off to allow tapping, though. At which point you might as well make your own, again it's a simple turning job. You wouldn't need to heat treat for your volume of work. It would not need to be a split collet. Bored for the tap diameter and relying on screws for grip and retention it ought to be fine. -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1916 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
