Help!
My Prusa i3 MK2S after hundreds (thousands, I suspect) of hours behaving has started moving its Y axis too far. Any ideas?
I’m trying to calibrate the printer after it started behaving oddly after a print went badly wrong (loads of spaghetti overnight).
Whilst the calibration is taking place, the printer stalls the Y axis, at both ends of the travel – I can see it’s up against the end stop (bearing at the front, switch at the back) and I can hear the thump-thump of the stepper skipping, so it’s not having its movement restricted, it really does seem to be moving too far.
Needless to say the calibration is failing.
Any ideas people? I’m stumped and I have a load of printing I’m supposed to be doing for others 
are you sure nothing has changed? Do you have a backup of the settings?
I don’t have a backup of the settings, but I don’t see why anything has changed – I haven’t been playing with printer settings.
A thought though: perhaps it’s normal for Y to stall during calibration and I just haven’t noticed in the past?
when you home the printer does the head go where you expect it to?
Yes it homes OK. I noticed that the bed was loose, so I’ve tightened that. Still no joy.
I’m wondering whether the steppers stalling in Y is a red herring, but I doubt it? If the stepper is stalling then the printer no longer knows where the bed is in Y, so that can’t be right?
I’m really puzzled. I swear it is moving too much in Y when calibrating – by several mm I would think (a couple of seconds of thumping after hitting the end of travel) – both when the bed is full back and full forward.
Currently wondering about resetting the printer’s settings in some way, or re-flashing the firmware, although that doesn’t feel like the right thing to do.
If the steps on the Y axis are incorrect you could try printing out a calibration cube to check how well the steppers are calibrated. You may have to think carefully about where you position the print so it doesn’t try and print off the bed.
Did you tighten the bed before this problem started, or after?
This sounds like a mechanical problem. Try to move the bed 1mm, measure the travelled distance, move the bed 10 mm, and measure again.
If the last measurement is not ten times the first, you are loosing steps, either by a mechanical problem, or less likely, a problem with the drivers.
Try this at different distances from home.
Tried a factory reset but still the same. Don’t think I can print any kind of calibration cube at the moment as the printer is out of calibration so it’ll either print in thin air or plough a groove in the bed (or a mixture, I expect).
Bed moves freely in Y, I can’t see anything jamming anything (no waste filament spaghetti anywhere I can see), printer still stalls after moving too far in Y during XYZ calibration, in both directions, which seems wrong to me.
I’m thinking about re-flashing the firmware, although that’s clutching at straws. I can’t help thinking that as it happened after the spaghetti monster, it must be mechanical somehow…
Can’t really see what mechanical issue would cause this. Edit your configuration.h file and increase the number of steps per mm to bring it within bounds. If you have the original configuration.h use that.
`This is the stock Prusa firmware – I’ve never had the need to build my own. As an aside, I have re-flashed the firmware, to no avail.
Now, I can believe that the printer has rattled itself out of calibration and it’s possible I will have to re-jig it to get everything square, so the real question is: does the i3 MK2 stall in Y whilst doing XYZ calibration? Is that normal? Is this a red herring?
That we don’t know, we build our own i3s. If you mean that it is not able to complete the sequence then this would suggest that there is a software issue, could be a sensor issue. We don’t use this method.
Maybe you updated your slicer software and now it thinks your print bed is bigger than it really is?
@Mark_Wheadon so does it trigger the endstop? And does the endstop work? check cabling and make sure that the endstop signal is received. You can check this by pressing the endstop and using a g-code to get status of endstops (google for it as I do not remember it). And also check the status when the endstop is not pressed.
@Kevin_Danger_Powers This is happening before anything is printed, during the printer’s setup calibration sequence.
I had this happen this weekend, though with the X axis. I cleaned and relubricated the rods, and then recalibrated the entire printer, and the problem went away.
@Craig_Trader So what symptoms were you seeing?