Z motors arent in sync

Hi all,
Ive got an interesting (if annoying) problem with my prusa mendel iteration 2, basicly ive leveled the z axis but after ive moved it all the way to the top and back down to the bed several times its no longer level, the idler end is approx 2mm lower than the motor end, its as if the motors arent synced, its got me totally stumped, the only thing i can think of is that its the motors themselves, they are nema 17's but i savaged them from a printer, but they are a matched pair so im not sure if this is the case, any ideas??

Could one have deteriorated? Are they getting enough amperage/voltage? If it is borderline, maybe one needs a bit more power than the other to avoid missing steps? Is there more friction on one threaded rod than the other?

On my setup with everything disconnected, if I spin one by hand the other follows. Is this happening with yours? I would check both sides that way.

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Yvan

Singularity Machine

Hi, thanks for your reply, ive greased the threaded rod but there doesnt seem to be any more friction on one than the other, if i have everything disconnected and manual turn one the other one turns aswell but not quite as much. Could the torque ratings be the cause? because i got there motors out of an old printer i cant be sure on the torque however a friend of mine thought they were around 25N.cm

Switching the motors around from left to right might be the next step. Now the idler side seems to lag, so if that switches sides with the motor, that would be a clue. How about the wiring and soldering points on the motors? Could there be a faulty connection there?

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Yvan

Singularity Machine

Hi there,

I'm interested to see if you ever came to a resolution to the Z axis sync issue ? did you find out what was at fault ?

-C

Most bed level issues are mechanical rather than motors. Things that look like motors often are couplings slipping.