Try ebay seller cwjkman , he sells surplus screws reasonably 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
