Y-axis not homing
I am wondering if anyone else is having a problem with the Y axis not homing correctly when a print begins.
If the bed is all the way forward when a run begins, as it is when after the last print completes, it only moves the bed back a few centimeters rather than all the way to the back. It thinks the Y is homed, then proceeds with the bed leveling procedure. It touches the first few locations on the first row, but when it tries to check the locations on the second row, the bed runs out of travel and the stepper motor makes a bad sound as it tries move the bed farther.
My work-around is to push the bed all the way to the back after I remove a printed part from the bed. If it starts off in the homed position it works. It didn't use to do this, but has done this ever since I installed the latest firmware (3.1.3-245). Do I have a setting wrong?
Re: Y-axis not homing
I would guess that something is binding your Y axis after it has moved the few centimetres, which fools the printer into thinking it has homed. Remember this printer measures resistance to movement as its virtual endstops - so to its limited senses a bind = an endstop.
Remove your Y belt. Check the bed movement. Check the bearings and the U bolts. Lubricate. Without the belt on the bed should run freely enough to move under its own weight all the way from front to back if you tilt the printer.
Once you have smooth front to back movement the problem should be solved.
HTH
Re: Y-axis not homing
the bed runs out of travel and the stepper motor makes a bad sound
Your Y-belt appears to be too loose tension, which makes it "jammed" (hence the noise).
Check the belt tension in the menu and tighten it so that you fall in the 240 ± 40 range.
Bear MK3 with Bondtech extruder
Re: Y-axis not homing
Make sure that there is a gap between the Y pulley and the Y motor body.
Also ensure that you don't have some filament strings wrapped around the Y pulley.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Y-axis not homing
Thanks for the excellent suggestions. I believe the belt tension is correct (256), and there is a gap between the Y pulley and motor body. However, there does seem to be some resistance when the Y stepper motor turns. It makes a periodic buzz as the bed travels forward and backward. So, when it buzzes I assume there is more resistance. When it is trying to home, perhaps it senses resistance and assumes it is at the end of the travel.
So, I guess my next move is to remove the belt and check bearings, U-bolts, etc. Is there a recommendation on lubrication? I will search the forum.
Thanks again for your answers.
Re: Y-axis not homing
Ha, well, I found my problem. I went and looked again at the gap between Y pulley and stepper motor. No gap! It was rubbing just a little bit. It turns out I could feel it rubbing. I just didn't know what I was feeling.
Now it homes perfectly. I am going to try turning the crash detection back on. I think little bit of resistance was causing the printer to detect a crash, and then forcing a layer shift.
Thanks again. I should have caught that myself. 😉
Re: Y-axis not homing
Hi - yes I found my Y-gear on the stepper was binding too - although it must have slipped.
I think I had the belt too tight ( is this possible 🙂 ? )
I think the belt being too tight forced the gear/cog out of the position I set when setting my printer up - because I set it up with forensic detail.
Thanks you guys were correct.