Missed steps on one axis.

[Lodran]

I'm getting a bit of lean on my Y axis - about 1mm in a 60mm tall print. I instrumented the motor step functions, so that I can track all steps after the printer is homed. From what I can see, it is always issuing the right number of steps, so you would expect the issue to be a mechanical one.

Thing is, it's not mechanical - If I replace the electronics with RAMPS, and run it with Marlin, it never leans. When moving the X and Y axis by hand, they move easily and cleanly (The printer is an Ordbot, so smooth movement on X and Y is pretty much a given).

That leaves motor current and acceleration as possibilities - The current is set at 1.5 amps, which runs the motors warm, but not too hot to touch. The motor driver is not overheating, as printer never misses a large number of steps at a time.

I've tried turning both acceleration and jerk settings down to aggressively low values, but the lean is still there.

I have to suspect that something's going wrong in the stepping logic, and on occasion it attempts to move the motor faster than is possible.

[se5a]

try disabling the endstops except when homing. it's a line somewhere in the config, you'll need to change it and re-compile. I had this problem and it took me about two weeks to find it was noisy endstops.

[Lodran]

That was one of the first things I tried. I've since determined that some of the lean is caused by the printer's frame, so I'm going to close this until I can come up with a test case that makes it obvious (I've had some models lean differently at different heights).