Well, I hope if G76 is indeed broken it can be fixed? Acme taps exist but are expensive. They are usually two stage in order to get the depth cut. We can do rigid tapping on the Emco but not sure if we have enough travel for the long tap and not sure we have enough torque at lower speeds to pull it off. Acme tap example: (https://www.amazon.com/Alfa-Tools-AT66572-8-8-Acme/dp/B00DYFSH30)
> On Jan 16, 2018, at 8:58 PM, Gene Heskett <ghesk...@shentel.net> wrote: > > I am inclined to agree in that g76 is broken in this regard. My feeling > is that it should retract to the drive_line, and no further. I have in > most cases managed a work around with the tools I have by jumping in 2 > directions, first being from USS threads to SAE, which are marginally > less deep, and then to the next bigger bolt if there is room for it. > > But from previous discussions, it appears your bolt size is fixed. Given > that, I only see one workable solution, which is to make, or buy if it > can be found, a tap, and use the g33.1, rigid tapping. This requires a > keyed to the spindle mounting for the tap, and adequate torque to turn > the tap. I have neither but I have gotten away with it by writing a peck > tap wrapper, advancing the end point only a small fraction of a turn per > pass ever deeper into the hole. When the tap is 8mm and above, its very > difficult to get a std er32 collet tight enough that the shank won't > slip, and I am talking about wrenches 18" long. Ditto the drawbolt of an > R-8 collet, with a 3/4" bore to hold a TTS toolholder. The TTS, > installed in an R8 collet, doesn't offer enough traction unless its that > proverbial 1/8 turn from broke. > > I'd call Nook and ask them where they buy the taps for making their nuts. > I've made carefull note of how proud they are when the asking for a 1/2" > 10 tpi bronze is right at $50/copy the last time I bought 2 of them. Its > possible they make their own taps. > > Humm, useing the tool you have in a small boring head, driven by g33.1 > might be workable as that would then back out at the same diameter it > went in. Put a spindle shut down to adjust the boring head, and a click > to run the next cycle, to the same depth, but a thou or 3 bigger each > pass. A boring head like Andy's would be ideal as its self incrementing > for diameter. > > Good luck Tom. > > 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 ------------------------------------------------------------------------------ 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
