Sporadic X Axis Stepper Motor

I’ve been looking through all the previous forums that outline issues with X or Y axis stepper motors.

After completing a series of 24+ hour builds - I started one today that during the first couple of layers had issues with what I thought was belt slippage https://dl.dropboxusercontent.com/u/92045468/20160407_124609.jpg. I re-tensioned the X axis belt to closely match the Y axis tension. Since all issues appear to be in the X axis.

After tensioning the belt - the issue persisted, so I disassembled the extruder from the mount, and removed the bearings to ensure there was no build up of dirt/debris on the them. Wiped down the rails and bearings and re-assembled.

Still nothing. I feel as though I’ve got the belts tight enough, I may go back through and attempt to tighten further as when I mark the belt to examine slippage after moving X direction +300 -300 +300 there is about a 1/2" misalignment.

Using pronterface I recorded a few videos showing the movement, and inconsistent speed of the stepper during movement.

Videos:
https://dl.dropboxusercontent.com/u/92045468/20160407_123217.mp4


A newly discovered issue is that when the steppers are energized - I’m able to move the X axis fairly easily…


Any help would be greatly appreciated, I’m running out of ideas…

It looks like you either have a stepper motor electrical short on two of the 4 leads to that motor, or the belt pulley itself is slipping intermittently. Or it could be some other electrical issue. But I’d check the connectors and cables, especially for a pin slipping out of the housing.

Solution found - removal of stepper motor revealed that the shaft had actually fractured off and was spinning only when a burr would catch.