I saw a similar idea for a damper years ago, except a square section copper ring was used in leu of the balls.
N. Christopher Perry > On Jan 24, 2017, at 12:45 AM, Gene Heskett <[email protected]> wrote: > > Greetings all; > > I see some "Nema 24" motors at quite reasonable prices showing up on > fleabay, in fairly high torque ratings, so I bought one 10 days back, > since I need a stronger one, with perhaps a damper on it on my x axis. I > bought the 8 wire model so I can drive it in parallel where I ought to > be able to get 3k rpms out of it. The mount bolt pattern appears to be a > duplicated of nema 23, but the body is just a wee bit fatter, the shaft > is double ended 8mm, and the whole thing looks like it will fit behind > the new apron with about 5mm of clearance between the back shaft end and > the face of the bed. So its perhaps 5mm longer than the double ended > nema 23 rated at 235 oz/in in there now. > > So I need to locate a 20 tooth, 8m bore pulley before I make the swap. > > Now, I don't believe this is going to help with the resonance stalls I am > getting at about 30 ipm, so I'm thinking of building a viscous damper to > fit on the rear of this puppy. But unlike the ones on my hf micromill, > which are long steel spools carrying a 2+ inch stack of heavy fender > washers with elastomer sheets between the washers, which are true shock > absorbers as the resonance is killed by the frictional losses as the > washers walk on the talcum covered elastomer, but I don't have room for > a 2+" stack of fender washers in this spot. 5/8" axially at best. > > I do have room for a larger diameter assembly on the back, so I am > thinking in terms of a 1/2" thick by maybe 4" in diameter alu wheel, > drilling in from the side at a low angle to put a couple set screws in > to clamp it to the motor shaft, and knock down 1 or 2 of my 00 buck 12 > gauge rounds, measure them, and bore as many pockets in the rim as I can > fit leaving about 20 to 30 thou for the balls to move within the pockets > filled with grease, and sealed over. A thin gasket to contain the > grease, and a 1/8" thick cap ring with a pair of 0-80 cap screws into > the fillets between the pockets should make a good torsional vibration > damper. Or plow a groove for a 1/16" o-ring on the outside of the cap, > and the inside radius of the cap ring on one side of it. Useing the > o-rings would tend to make the grease self distributing, and the small > clearance might even aid in the damping if I intentionally plow a > shallow 3rd groove between the grooves for the sealing o-rings would > further enhance the viscous losses of the grease moving back and forth > between pockets thru that narrow passage. > > What do the vibration engineers in this crowd think of this idea? > > 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
