Mini Bed Belt Pulley Slipping

Just started a print on my Mini, and while the bed was extending outward to its farthest position to be prepped, the belt that drives it started slipping. Made a horrible ratcheting noise, and wouldn’t stop till I cut the power. I tried twice more with the same result.

I can’t see anything caught in there. Any suggestions? Is the belt maybe worn out, or is it possibly a calibration issue?

Mini 1 or 2? For either check belt tension.

On the 2, check the sensorless homing sensitivity.

Thanks for asking: it’s a Mini 1. So how do I check or adjust belt tension?

Check the OHAI website for Mini 1.03 and 1.04 assembly instructions. I would think there would be belt tension instructions there.

Thanks, I’ll check it out.

So on closer examination, I don’t think the bed drive belt is loose. It seems to work just fine making small adjustments on the Y-axis.

The problem occurs only when it gets to (or very close to) the home position, fully extended out front. That’s when it starts juddering endlessly.

Is there some sensor that tells the bed that it’s reached the home position? Or some way to recalibrate the bed’s actual position? I tried reducing the Y-axis length settings from 154mm, but it didn’t help.