XYZ Calibrations run fine but auto home doesn't.
Hi I'm having an issue with my Prusa i3 MK3s. I've had a total of 14 days of printing since I got my printer, however in my last print I had extremely large layer shifting in the Y axis. The layer that caused the crash was off by about an entire inch towards the back of the printer.
Since that crash I haven't been able to print correctly. And my printer won't auto home correctly. When running auto home the Y axis stops around the middle of the bed. I have ran XYZ calibration and self test multiple times and neither of those fixed anything. I then updated the firmware to the latest version and that didn't change anything and I also did a factory reset and that also did nothing.
I also looked through this guide https://www.prusa3d.com/layer-shifting/ I tightened my Y-axis belt as it's value was 302. But whenever I auto home it still stops in near the middle of the bed in the y direction instead of going all the way to the left corner which says "print area" on the bed. I also tightened the screws in the pulley some more, but they didn't seem to be the problem because they were already pretty tight.
One thing I do notice is that it's much much easier to pull the bed to the front of the printer than it is to push the bed to the back. I don't know if this is normal or not.
This has all been pretty frustrating so I hope no one else has had this problem, but if you have some help would be appreciated.
RE: XYZ Calibrations run fine but auto home doesn't.
Does your XYZ calibration end up successfully ? Any error message during the unsuccessful print?
Edit: how the first layer calibration looks like? does it perform correctly?
even an old man can learn new things 🙂
Standard I3 mk3s, MMU2S, Prusa Enclosure, Fusion 360, PrusaSlicer, Windows 10
PRUSA MINI+ Prusalink + Prusa Connect
RE: XYZ Calibrations run fine but auto home doesn't.
@zoltan
The XYZ ends successfully stating that the axes are perpendicular. No I can't perform a first layer calibration because it thinks that the home position is midway through the y axis which is a problem when it tries to start at the back of the bed and come forward, by doing that it tries to move the bed too far forwards further than is possible.
RE: XYZ Calibrations run fine but auto home doesn't.
"One thing I do notice is that it's much much easier to pull the bed to the front of the printer than it is to push the bed to the back. I don't know if this is normal or not."
This is your smoking gun. This is absolutely not normal. You have some mechanical issue stopping the bed from moving that needs to be fixed. When the bed becomes hard to move the Trinamic drivers are interpreting that as the bed has reached end of travel. Hence the printer now thinks Y home is halfway through the travel.
Fix your mechanical issue (belts / bearings) until your bed travels smoothly all the way from front to back. That will solve the problem.
RE: XYZ Calibrations run fine but auto home doesn't.
The bed should slide back and forth under gravity: lift the printer at the front a few inches and the bed will slide to the rear, lift the printer at the rear and the bed will slide forward. Back and forth should be very easy and no difference.
U-bolts that are too tight will cause what you are experiencing. Loosen them so they wiggle, then tighten until they don't wiggle; no more or you deform the bearings and they seize.