Gene, As far as I know ALL R8 collets have a 7/16"-20 UNF draw-bar thread, if it does not have that it is not an R8 collet! Your TSC does not stock UNF bolts? Pretty sure the ones around here stock both UNC and UNF in at least Grade 2. I know ACE stocks both UNF and UNC in Grade 2, 5 and 8 as well as in stainless, but we are lucky to have one of the better ACEs.
While on the subject of thread standards ... I can't find it mentioned anywhere, but there is also what is sometimes referred to as a UNUF (Ultra Fine) thread. I guess it is not officially part of the UTS since I can't find a reference anywhere, but I have seen it referred to as UNUF on drawings and part lists. The "UNUF" I have encountered is 100tpi on small (#10 and .25") set screws used for making fine adjustments on optical instruments and stages. You can get them from supply houses such as McMaster, so they are more or less standard parts. Cheers, Kurt On Mon, Apr 2, 2018 at 11:52 PM, Gene Heskett <[email protected]> wrote: > On Monday 02 April 2018 21:33:22 David Berndt wrote: > > > What? What exactly is the pitch/sizing on a USS bolt? Google doesn't > > really return much for a USS thread chart... UNS? 7/16-18? TSC was > > formed in 1938, perhaps you got their last piece of original stock? > > Their drawer marking is still old style, uss & sae. When they actually > label it that is. > > Eeecks! > > They changed the designation when I wasn't paying any attention, one of > the hazards of reaching my over-ripe age I guess. > > At <https://en.wikipedia.org/wiki/Unified_Thread_Standard> Nowadays it > appears what used to be USS is to be called by "UNC" (14 tpi for a > 7/16") and SAE is to be called "UNF" (20 tpi for a 7/16"). Ack > wikipedia, there is also a UNEF (28 tpi) but I've not seen one of those > critters in my 83 years plain enough to remember it. > > Its likely a good thing you called me on it, else I would have carved a > hunk of A2 to 18 tpi tomorrow. And it still would not have fit. > > But now I'm curious, do I have metric threaded R8's? The 14 screws in a > few degrees over a full turn before it jams. But the R8 is Bridgeports > pet tool holder so I assumed it was an American bolt. And taking this > one out of the G0704 is, shall we say, a "project" thats is not going to > happen unless it fails. So I'd better get out my taps and see how a > 10mm coarse thread fits in one of these, I might have a crossbreed of > some sort. If you hear muttering from North Central WV by the time the > weather passes by tomorrow, you'll know why. > > Thanks for the gentle reminder. I think you may have saved me from making > a mistake. > > > On Mon, 02 Apr 2018 19:35:27 -0400, Gene Heskett > > <[email protected]> > > > > wrote: > > > I rigged the 5C to ER-40 to the mills table, then found I needed a > > > draw bolt about 4" long to keep the R8 from rotating in the ER40 > > > collet. So I saddled up and ran out to TSC, where I found the 7/16 > > > bolts they had were only grade 5. So I got one and some washers to > > > adjust the length with, came back and found the bolt was USS while > > > the butt end of the R8 was SAE. So I'll have to round up some 1/2" > > > A2 and put it all back in the lathe to apply a g76 and make some SAE > > > threads. > > > > > > I also found I'll need a better way to clamp it to the table, > > > probably by making a big v-block and a thick steel bar to clamp it > > > into the V. > > > > > > Some days I swear its not worth gnawing thru the straps to get up > > > and pee in the mornings. :( > > -- > 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 > [email protected] > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
