Printer "homes" mid print.
Hi all.
Sorry if this is a duplicate topic, I have searched but nothing seems to cover our problem.
One of our i3 MK3S (3.10.1-4697) printers will suddenly (sort of) "home" mid print. Invariably the X axis shifts slightly, so the print becomes offset. Subsequent "homes" during the same job will usually move the X axis closer to the original position, but not always. The print job shown is printing in the center of the bed, and all axis are smooth and free. (Hopefully I have managed to include a video clip of the failure)
https://forum.prusa3d.com/wp-content/uploads/2022/05/Prusa_Homing_LoRez.mp4
My question is: What triggers the software to "home" while printing?
Many thanks,
Garry
Best Answer by fuchsr:
Is crash detection on? If so, I'd turn it off. For me it did more harm than good, turned it off, never looked back. And check the IR filament sensor.
RE: Printer "homes" mid print.
Is crash detection on? If so, I'd turn it off. For me it did more harm than good, turned it off, never looked back. And check the IR filament sensor.
RE: Printer "homes" mid print.
That seems to move the same distance in each direction. Check motor pulley screws
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Printer "homes" mid print.
Hi.
Thanks for the suggestion.
We have checked the belts, belt tension, motor screws and motor pulley screws.
The offset is not consistent, sometimes it will move a certain amount, then a bit later move back to almost, but not quite, the original position.
It seems to be less a slip or a jump, and more the "homing" coming up with slightly different position each time (which is totally reasonable and to be expected). If we could only figure out what is triggering the home sequence.
Many thanks,
Garry
RE: Printer "homes" mid print.
Hi,
> Is crash detection on?
Yes. I will try turning it off and see if this helps (though it doesn't complain about crashing).
> And check the IR filament sensor
What would I be looking for in particular?
Many thanks,
Garry
RE: Printer "homes" mid print.
I would consider lubing the smooth rods because homing position is based on motor stall current, if there is additional friction, it can trigger early.
regards J0an
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Printer "homes" mid print.
> And check the IR filament sensor
https://help.prusa3d.com/article/ir-filament-sensor-troubleshooting-mk2-5s-mk3s_112226
But I begin to suspect I took your use of "home" literally, as in, print heading going to home. But reading your post again it seems you're talking about layer shifts. Here's my usual "list of suspects" for layer shifts (I understand you've checked some of them):
* Grub screws on X motor not properly tightened. One has to be tightened against the flat side of the motor shaft!
* Belt not correctly tightened. Use this tension meter to get it right: < https://www.prusaprinters.org/prints/46639>
* X carriage over-squeezed. Loosen the back plate on the X carriage axis.
* Nozzle hit an obstacle. Some patterns such as grid have lines that cross within one layer. This can lead to little pile-ups at the intersection points, in particular if you have slight overextrusion, which in turn can lead to the nozzle catching at those pile-ups. See < https://help.prusa3d.com/en/article/infill-patterns_177130/>
* Zip ties on the wire bundle on the back of the extruder not properly positioned, so they or the cables hit the model.
RE: Printer "homes" mid print.
Hi Joan and fuchsr,
Thanks for your help. Checking the fault counters before and after a "glitch" we found that the Y crash counter had incremented by one.
Turning crash detection off allowed us to print an entire problematic model with no issues.
We will now clean then lube all guide rods and then turn crash detection back on and see if this has helped.
Again, thanks for your help!
Garry