Keling NEMA42 2830oz-in motors vibrating

[mcArch]

I have two KL42H2150-42-8A Nema 42 2830oz-in step motors running the gantry on this 5 axis machine: http://www.cnczone.com/forums/plasma...a_10x5x24.html The motors are vibrating quite a bit and I cannot tune them to be smooth enough. I have tuned them using the trimpot on the Gecko 203V's & can get them pretty quiet at ~0.5rev/sec, but not silent & at some rpm they are really noisy. I am using Gecko 203V's at 6amps for drivers & 72V (KL7220) power supply. Is there some other way I can tune them to run more smoothly?

I have it running on Pacific Bearing 25mm Profile Rail, could this have anything to do with it if it were in need of grease?

They are 8 wire motors & I have them wired Bi-polar parallel, will a different wiring run more smoothly? Lower voltage? Seems to be vibrating way too much.

I spoke with Keling & they are sure that it's not the motors as they have sold hundreds of them & have not had any problems + they say because it's both motors doing the same thing, it's most likely some other mechanical issue. Any ideas anyone? Thanks in advanace.
Cheers!
-Calvino

[MillworkMike]

Im pretty sure its The Nature of the beast!! Alot of people say stay under 1200in-oz steppers for that reason. The Keling 906in-oz Nema 34s with a 3 to 1 belt reduction would give you more torque and you would have almost no vibration. Then again I may be dead wrong so lets hope some one else will chime in and give there opinion.

[mcArch]

Thanks MillworkMike . . . These are on a 3:1 belt reduction already. I'm going to check the #'s & see, maybe I can go down to a pair of HomeshopCNC's RS34-1840's & still have enough torque to push that 5.3hp spindle through hard woods & some alum. Throuble is that gantry + the Y & Z & that big spindle weigh about 500 - 600# + I need about 150# to push that spindle, to match everything up. Actually, that's not that much force required of the motors with the 3:1 & the 1"pitchDia. I'll check the #'s on it.

Any other thoughts anyone?
Thanks
-Calvino

[Zygoat]

normally with steppers it would be the drivers causing issues. but you said you are using geckos, so i doubt it. you could always talk to them to be sure, see if they have any ideas/ suggestions.

assuming that will lead no where. you could always try dampers.


read this thread.

http://www.cnczone.com/forums/steppe..._damper-7.html


here is a video that sum's up the effect pretty well. (from that thread)



in the simplest form some people just shove a hockey puck with a hole drilled in the middle on the shaft.

hope that helps.