Nozzle crashing into the bed during calibration
Hi everyone!
I started a print but aborted it due to some issues on the model that needed fixing. I started another run almost immediately afterwards and the printer failed to properly calibrate and instead crashed into the bed while searching for the front/right calibration point, leaving a rather deep point scar behind:
I tried to redo the XYZ-calibration, which succeeded in finding the first (front/center) point, but failed to find the second one (right/center). This resulted in the nozzle descending further and further while going back and forth until finally scraping across the bed. This is the resulting damage:
I cut power at this point to prevent the extruder from further damaging the bed, so sadly no error message.
It would be very surprising if the bed died in the short time span between those two prints. The printer was not even turned off or modified somehow in the meantime.
Can anyone help me figure out what is going on?
EDIT: Flashing the newest firmware (v3.0.9) does not seem to fix this either.
Re: Nozzle crashing into the bed during calibration
Have you checked your PINDA-probe? This is often a result of the probe coming loose, use some loctite when fastening it.
Re: Nozzle crashing into the bed during calibration
Yes, I checked the PINDA probe. It is definitely not loose at all and has worked properly for many prints prior to the failure. This leads to my assumption that the probe mounting is not the issue.
I think it is also curious that both instances of the detection failing are on the right side of the bed (front/right and center/right), but I do not have a fitting hypothesis yet.
Re: Nozzle crashing into the bed during calibration
Yes, I checked the PINDA probe. It is definitely not loose at all and has worked properly for many prints prior to the failure. This leads to my assumption that the probe mounting is not the issue.
I think it is also curious that both instances of the detection failing are on the right side of the bed (front/right and center/right), but I do not have a fitting hypothesis yet.
And you haven't lifted the printer or accidentally managed to get the Y-rods to not sit all the way down into the frame?
Are your Z carriage all the way up before you start the calibration?
Re: Nozzle crashing into the bed during calibration
The printer has not been moved at all between the print that worked and the print that failed and the Y-rods are positioned correctly (I just double-checked).
My Z-carriage definitely was all the way up (also double-checked), because this was my initial suspicion as well.
I should probably note that the nozzle goes back and forth over the second point for a while before it begins touching the bed. It just does not stop in time. So the problem is probably not that it starts out too low (which would be caused by the Y-carriage not being aligned properly I guess).
Thanks for taking the time, by the way! 🙂
Re: Nozzle crashing into the bed during calibration
Maybe broken PINDA cable loses contact when the extruder is on right side? Did you try to trigger the probe by hand using piece of metal to test its function over problematic probing point?
Re: Nozzle crashing into the bed during calibration
Are you running the latest firmware, I noticed on before on older firmware that after a cancelled a print operation strange things happened (i.e. print head collided with bed on next print) powered printer on and off and all was well again...
Re: Nozzle crashing into the bed during calibration
Yes, I am on the latest firmware (see my original post).
I also just tested the PINDA cable theory and it seems to be the cause! Pushing the cable to the side during search fixes it! This probably means that the whole probe needs to be replaced since the cable is not detachable.
Thank you all so far!
Re: Nozzle crashing into the bed during calibration
Exactly the same problem I have on one of my MK2's. I noticed it during a print where it would hit calibration point 3 and just stop. There is a short in my cable and had to order a new probe from Prusa. Shipped today so I should have it before the weekend.
Re: Nozzle crashing into the bed during calibration
richard.i A short in your cable, where? A cable can be repaired outside the Pinda probe, so no need for a new pinda. My first job was a TV repair man before my A levels. I was taught the obvious is often the fault. Only after the obvious get out the Oscilloscope for TV waveforms . Or last resort replace an entire part. Back in the good old days 🙂 Before total LSI.
The cable can be spliced.
Nigel
Life is keeping interested and excited by knowledge and new things.
Re: Nozzle crashing into the bed during calibration
Merv
True, the cable can be spliced but it will be hard to find. I will try that once I get the replacement in. If successful I will have a ready spare.
Re: Nozzle crashing into the bed during calibration
Richard
The "usual" place for the probe cable to become fractured is at the back of the extruder where the long cable tie is located and where the cable turns 90 degrees to join the cable bundle.
Splicing at that point is not ideal; it would be better to replace a section of cable around that point.
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: Nozzle crashing into the bed during calibration
Yes, that is exactly where the cable seems to have failed in my case. Splicing it is not ideal, but it will be a last resort.