On Sunday 02 July 2017 09:15:05 jeremy youngs wrote: > Try ebay seller cwjkman , he sells surplus screws reasonably > I found him, but how do I do a search within what he has?
I was not able to find loose balls that are oversize. I /think/ they are .125 and 3.25mm are hens teeth. Also. I found some screws, a pair of them TBE, with dual ball nuts. <http://www.ebay.com/itm/2-set-Anti-Backlash-Ball-Lead-screw-RM2505-1500mm-C7-Dual-Ball-nut-end-machine/152072443766?_trksid=p2046732.c100040.m2060&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20140107095009%26meid%3Df4f402ce00d94286a67ccc7b7b3cee5e%26pid%3D100040%26rk%3D4%26rkt%3D4%26sd%3D232093037158> Can anyone tell me if what I see in that set of pix, the coupling tabs with a screw in only one end, is a way of adjusting the phase and therefore the backlash of that nut style? By making the coupling tabs with an offset for instance? Or perhaps some Reynolds wrap shims between the 2 halves? These are 50mm longer but that would allow me to remachine the ends for a better fit as the 1450 I put there a year ago is a tad short, on the driving end in particular. That short 10mm stub needs to be at least 15mm longer than shown in order to fully seat the timeing pulley on it. And another 25mm would give me room to do a taperlock hub, which I've grown very fond of over the last 60 years. They do not slip and do not need a keyway to do it. > On Jul 2, 2017 12:12 AM, "Gene Heskett" <[email protected]> wrote: > > On Saturday 01 July 2017 21:34:27 Gene Heskett wrote: > > > Greetings guys; > > > > > > That <$200 2505 by 1475 screw I used for z drive is haunting me, > > > again. > > > > > > First, I never did get around to shimming some preload into the > > > thrust bearing, so a years messing around later, the far end of > > > the screw is moving around .0055" as it takes up the reversal > > > slack. And obviously the balls in the ballnut need refilled with > > > decent balls about .005" bigger. > > > > > > Then today I made a cutting tool, .0495" wide, to cut those 10 tpi > > > square threads I'll need on the end of this barrel, and I am > > > damned glad I picked up a piece of pvc pipe to practice on. > > > Setting g76 with a q0.000, I found it was drifting left > > > approximately .001" per cycle, and that a q-0.5 helped but > > > something wasn't slipping uniformly, so I added a microsecond to > > > the driver pulses, no diff, then started on the mechanicals, so > > > the first 5 or so passes did not result in a usable thread. I > > > wound up snugging up the setscrews in the motor pulley, and in the > > > pulley driving the screw before that seemed to settle. The > > > backlash seems to vary at random by about 2 thou, so the starting > > > point of each sweep to the left at cutting depth wanders around > > > about 2 thou. > > > > Now, there is one problem with committing all this to gcode. The is > > an extractor clearance that reaches across the back face, and which > > must be timed to the end face that stops the barrel at the proper > > rotation angle such that this relief is exactly centered on the left > > side. But the drawings I can source, do not give a measurement! So > > one would have to to test fit it, and trim the stop face forward by > > making the cutaway, then measureing the angle to determine how much > > to face off of the stop face to bring the recess to the proper > > location. > > > > It could be rather handy to have a starting angle variable for the > > g76 cycle that we could use to delay the start of the threading pass > > in relation to the index pulse in order to duplicate what we can > > measure on the shot out barrel being removed. > > > > The 800lb gorilla is: would that bring LinuxCNC back under the ITAR > > restrictions? > > > > > I can, its a pita to do, reynolds wrap the thrust bearings to get > > > a bit of preload, which would cut the backlash in half, but where > > > the heck do I find oversized balls for the nut that are that > > > grossly oversized? AFAIK, its a std Chinese 2505 ball and screw, > > > but I don't have a clue how big the std balls for one of those > > > critters are. > > > > > > Has anyone here tried to rebuild one of these, or are those rolled > > > screws and its equally cheap nut so soft I'd be wasting my time? > > > > The only replacement I can find is another C7 grade, with freight, > > $165 on my front deck in 5 or 6 weeks. Another twin to this one with > > its sloppy build doesn't pull my trigger. C5's and C3's add $500 or > > $700 more. If I can src the balls, I'll gladly re-stuff this one. > > > > > Thanks all. > > > > > > Cheers, Gene Heskett > > > > 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 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
