On Wednesday 11 December 2013 17:55:39 Leonardo Marsaglia did opine: > 2013/12/11 Gene Heskett <ghesk...@wdtv.com> > > > Question: Is this enough of a velocity variation to effect the > > performance of the hardening process? Or cause premature wear > > anyplace from the vibration, like in the cable trough feeding this > > carriage? > > I found the velocity variation quite good for the hardening process > since it takes 1 second aprox between the finish of the heating and the > cooling process so I think it's going to be ok on that side. About the > stress that the parts could have, well the system is rather made to > last, the carriage is supported by two round steel guides of 80 mm and > they are coated, I don't think the machine in the original state was > quieter than this, because we only replaced the original bronze nut for > a new one made out of nylon. > > > Maybe this is a case where the vibration dampers on the rear end of > > our steppers that are often used, might be expanded into a damper big > > enough to absorb the majority of this "vibration'? > > The nut itself it's mounted over a plate that has a few milimeters of > travel in all directions except in the direction of the movement of the > joint. So this way it can suit any variation on the machine. But the > coupling on the motor it's direct steel with steel so a damper could > help a lot. > > > This damper gismo isn't an area well characterized, or at least I've > > not found someone proposing formulas for their making on the net, so > > most of use make our own according to our own thinking. If the rear > > shaft isn't available, then a thin flywheel on the drive end, with a > > tubular rim filled with large ball bearing balls for rolling weight, > > running in heavy grease to dampen the motion of the balls relative to > > the rim could make a noticeable difference, but with the reduced rate > > of available acceleration that swinging weight would cost. Not > > talking my nema 23's here, where such a constuct might be the size of > > a roller skate weheel but something perhaps 8 to 10" in overall > > diameter, keeping in mind it needs to strong enough to take the rpms > > involved. It goes without saying that its demise at speed would of > > course become quite a hazard. :( Containment cages could be > > indicated/demanded by the safety people. > > I think I can get some dampers that are often used for hydraulic pumps > and so, that could work well for this job. After all I don't need the > accuracy of a lathe. Anyway I was thinking that also a big ballscrew > (50 mm or diameter) would be of help because the force that the motor > has to do to break the inertia will be a lot less than now with my > steel screw and nylon nut. This is an idea for the future of course now > I need the machine on production :). > > I will try to uplad some videos this weekend.
Huge yabut there. Co$t... The precision of the ball screw apparently isn't needed, and keeping it clean for long life could be a problem, particularly when the nylon nut can be replaced several times during overnight maintenance for 2% of the cost of the ball screw and nut that size. Assuming reasonably clean screws, and a heat formed acetal/delrin nut I'd think screw/nut life would be quite reasonable and its lower friction compared to nylon, a win-win. And heat molded acetel can have backlash under .001". Just shield it if you can from the induction heating. External air coming it would lower it 100F or more, doing wonders for any "cold flow" the constant weight might induce. So would gun drilling the screw and running room temp recycled water through it if the screw gets too hot to touch. Easy if the nut is driven and the screw mounted rigidly. Cheers, Gene -- "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> My computer, my documents, my briefcase, my ASS! -- Ben Cook A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
