Layer Shift and Strange High Motor Resistant Issue
I have a MK3S+ that has been running for years about 3 to 5 days a week. Some times more. Recently I have started getting layer shifts every print unless I print at 80% speed or bellow and even then sometimes. This happens on both the X and Y axis. There are no odd sounds during movement of the x or Y axis. When running the belt self test, both results come back at a crazy number in the 160s. Both the X and Y belts are not crooked when looked at from on top or from the side. Setup Wizard passed setup with no issues.
What have I checked and tried to fix:
Guide Rods Cleaned and inspected for damage. (No Damage)
Guide Rods and Bearings lubricated with Super Lube Grease ( No change in belt test number)
Belts loosened (No effect in belt test number)
Belts tightened. (No effect in belt test number)
Belts taken off and both Axis smoothness tested without belts. Both axis are smooth. With belts there is a decent amount of resistance but no uneven jerks.
Y axis Guide rods were re-settled after loosening the front and back plates of the frame (No effect).
Motor Pulleys checked. Both have the grub screw tight and aligned to flat part of shaft.
Idler pulleys checked. Smoothly free spinning.
Idler pulleys changed. (No improvement).
Obstructions around the guide rods checked (None)
Issue noticed:
If I take the grub screws off of the motor pulley, leave the belt on, and move the extruder back and forth by hand the pulley moves forward on the shaft when the extruder is at one end and then moves back towards the motor on the shaft when the extruder is on the other end. This also happens for the Y-xis motor pulley. To me that seems like the X and Y axis are skewed, but I can't figure out how that is so when the belts are aligned and the bearings run smoothly on the guide rods and that I don't see any crookedness anywhere.
I am kind of running out of ideas and hoping someone can point me in a new direction. The only thing left in my mind is some sort of structural issues with the frame itself or the printed pieces holding the motor/pulleys or with the motors themselves.
Are there recent, apparently false, crashes in the logs?
With power off move the axes by hand - are they smooth?
Remove belts and turn the motors by hand. You should feel the steps but otherwise smooth, no grating, likewise turn the idler pulleys with some pressure (use the belt) are they still smooth?
When idler bearings, or internal motor bearings, are failing the resistance under pressure can be the first symptom. Uneven belt alignment can be hard on bearings.
Cheerio,
RE: Layer Shift and Strange High Motor Resistant Issue
Yes, I checked the cash logs and there is a lot of crashes apparently.
Last Print:
Filament run out 15
Crash X 14
Crash Y 168
The last print had a X axis layer shift and no filament runout or layershift in the Y axis.
With the power off and the belts on, moving the extruder on the axis and the build plate in the Y axis is smooth but there is some resistance. The resistance is consistent through the motion from end to end.
I will take off the belts and check the pulleys by hand in a bit and will update.
RE: Layer Shift and Strange High Motor Resistant Issue
Having taken the belts off again, the extruder runs very smoothly on the x axis. So is the build plate on the Y axis. Both idler pulleys are very smooth when moved using the belt. The main point of resistance is the stepper motors. When i spin the motors by hand I can feel each step. There is a decent amount of resistance. More so than on the extruder motor, but that could be because they are different types. I dont hear any grinding or feel any sticky spots when i turn the motor but as I said earlier, there is decent amount of resistance. I don't know how much resistance there is supposed to be, so i don't know if it is normal or not, but it is spinnable with one hand, just not super easy to do so.
All those false crashes do suggest bearing issues, the stepper resistance should be perceptible but light.
Cheerio,
RE: Layer Shift and Strange High Motor Resistant Issue
Well, the Stepper Motor seemed to be the only issue left so I took it off and switched it for another one off of my MMU. resistance numbers instantly went from 170s to 270s. It appears I have worked both my X and Y motors to death. Time to get new ones. Thank you very much Diem.