On Tuesday 03 April 2018 00:40:27 Kurt Jacobson wrote: > 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. > I wasn't aware of those. Usually I've just made my own, but not finer than 50 tpi. But since putting tapered gibs in the 7x12, I think it could do 100 tpi stuff now. I haven't tried anything like that on the sheldon, but with hand sharpened HSS tooling I don't see why not. it did true up its own spindle by regrinding the short MT5 taper in its bore. Well enough an ER-40 adaptor runs at under .001 TIR 4" from the collet. And after the same grinder on the faceplates, the big chucks run pretty true.
And I'd like to cobble up a target to mount in the tailstock, and a laser diode in the spider so I could measure bed wear and calibrate that out with a lincurve/offset combo. The bed doesn't look that bad, but... I didn't attempt to do tapered gibs when I rebuilt it, figured the carriage was heavy enough to hold it, but have since found thats not the case, I have seen it lift the 10 thou or so before the new gibs catch it. Later this summer maybe. At the same time I put some preload in the z screw thrust bearing. Despite some Reynolds wrap shims, it still has 3 or 4 thou of end play. > Cheers, > Kurt > > On Mon, Apr 2, 2018 at 11:52 PM, Gene Heskett <ghesk...@shentel.net> 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 > > > <ghesk...@shentel.net> > > > > > > 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 > > 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 -- 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
