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
