On Tuesday 06 March 2018 23:31:20 Jon Elson wrote: > On 03/06/2018 10:05 PM, Gene Heskett wrote: > > Greetings all; > > > > It appears that its well nigh impossible to get a firm enough grip > > on a tap shank, and on the smooth, unkeyed TTS ER-32 holder, to > > reliably lock a tap for rigid tapping. I've considered buying > > ER-32's with square sockets, but for >8mm taps, the TTS > > adapter/holder will spin in the R8. > > There are tap chucks that have a round shank, and will fit > in collets or end mill holders. > You can also take the handle out and use a standard tap > handle in a collet or big Jacobs chuck, although come of > them are not centered well.
I've tried that several times Jon, and the resultant eccentricity pretty much makes a 9-32 hole using an 8-32 tap. That crap is stamped out of wheel weights I think. Perhaps I could braze on an expansion sleeve, then turn it true, bringing it up to 3/4 in diameter for better traction in the R8. But whats needed as a universal fix, is an R8 to tap thats keyed. I'm thinking of, when I can locate the square socket R8's, boring it round for 1/2" or so, and only 5 thou bigger than the opposing corner to opposing corner of the tap. That should hold the tap fairly true. > > I do rigid tapping with small taps, but have gone up to > 10-32 without slipping. A 10-32 in alu is usually ok, but an 8mm in steel is not a working setup here, and this is with 15 to 17 inch long wrenches tightening the ER-32 nut. The limit there is the drawbar's teeny little square butt. I could put an 8 point socket on it, but by the time its truly locked, I can feel the threads on the bolt, or in the collet, giving way. And gaining access to replace the drawbolt in a G0704 is, because my spindle encoder is in the way, not a very quickly done job. > > Jon > > ---------------------------------------------------------------------- >-------- 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 -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ 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
