Quote Originally Posted by clough42 View Post
Has anyone else had any trouble with the auto-bed-level sometimes not running or not completing?

Sometimes, the G28 runs, and it homes in the center, but the G29 sequence doesn't run and the printer is left with the Z level off by about 6mm. Those first layers don't adhere to the bed real well when they're applied from 6mm up.

I haven't figured out how to reproduce it at will yet, but it seems to happen if I've already run one print job and haven't reset the printer. Or maybe it's just happening when the Z axis is high (90mm or more) and it takes a long time for the G28 Z probe.

Ideas?
I used to have that problem. And yes, it was because I had finished a tall print, and it took the printer too long to home the Z axis that the X and Y steppers timed out and were deactivated, losing the X and Y home position. G29 will not run in this case, so I changed the stepper deactivating delay from (I think it was) 40 to 150. I haven't had the problem since. Sorry, I cannot remember where the setting is in the firmware.

edit: configuration_adv.h
//default stepper release if idle
#define DEFAULT_STEPPER_DEACTIVE_TIME 60

I changed the 60 to 150.