My M300 will often allow the build plate to lower when the power is turned off, especially if I still have large print part on the platform, I think it is because the M300 build plate is so heavy. Mine still works properly once power is restored.
My M300 does not get jammed when fully down.
If your printer only gets jammed when fully lowered you could place something in the bottom of the printer to prevent the bed from falling completely to the bottom, l would suggest something compressible like a sponge foam block.
If you would be able to record that behavior on video, would be great.
When the Z motor turns off, the platform moves down under it's own weight, reaches the end of the screw, where in this particular case, for some reason (steeper angle of the z-screw threading at the end?) the torque needed to move it back up is higher than what the motor can provide.
The platform moving down on it's own when the motor is turned off is normal. The platform getting stuck isn't, I haven't seen anything like that on any M300 I've worked on.
I'll try to get a repro on this. I'm thinking starting off the motor with a lower RPM (=higher torque) initially should be enough to get this fixed for the next release.
if we start Kalibration and disconect the heating plug the bed move to adder direktion ! and after time stope and give message missing signal plattform
second problem if we start Referenz the Platform move always down never up
um...usually that is the first place you start, then off to the forum to see if anyone else had similar issue. But no video and having English as second or third makes for a bad diagnosis. lol
I have M200 1st Gen but sounds to me like loose wire but having more info is always helpful like when it started..after a successful print or never been able to get a print...stuff like that I think would be helpful but I'm no engineer.