I have a problem with the up movement of the Z-Axis. It intermittently struggles and fail and then goes back down making a loud grinding noise. The motor is failing to lift the head as there appears to be too much friction. It is an intermittent problem, works fine for a while and then fails. Could this be a motor issue? Anyone experience this problem?
See videos;
Any help would be much appreciated. Thanks, Matt
We are having a similar issue when its moving up. Its not grinding like yours, but it wont go up unless you are helping the screw with your hand. It goes down ok, but ours sounds like its grinding of sorts as well… not as bad as that though. Is movement up an issue with farmbot in general?
I think I found a solution. 
Set max speed at 150, and acceleration for steps at 450. It moves a lot slower but no more problem with the up movement for now.
Mine still has this z-axis movement issue. Other ways to improve z-axis movement? Mine will make loud squeaking noise when moving down, and will have a hard time moving up. I changed max retries to 10, but still, sometimes it will stuck. And this seems to only happen when performing seeding related movement when z-axis is really low. It is fine when z is higher up.