XYZ-calibration fails at first point ("Bed calibration point was not found")  

XYZ-calibration fails at first point ("Bed calibration point was not found")

Hi guys,

happy to be with you. 😉

I've just upgraded our Original Prusa MK3S with the MMU2S. Before the upgrade I could print examples very well with no problems. It was an already assembled one from the prusa shop.

I did everything according to the guide on help.prusa3d.com and got to Step 9 of Chapter 8:"Preflight check". I performed "Calibrate Z" and then wanted to calibrate XYZ as well. At this point I am stuck.

I'm always getting our printer to start scanning for "calibration point 1" with the PINDA probe. Its scanning over the marked circle on the heatbed. For me it looks like its scanning the right area. But in the end of the procedure for "calibration point 1" it stops and gives me this error: "XYZ calibration failed. Bed calibration point was not found."

I investigated the manual for guidance and also searched for similar problems in the forums. So far I didn’t find the reason for my problem.

What I tried so far:
- factory reset and new flashing of MK3S with "prusa3d_fw_MK3S_3_9_1_3518.hex"
- readjusting the PINDA probe like explained in Chapter 8 Preflight check Step 1 through 3. I did this several times. First the distance between the PIND probe and the nozzle was about 1.2mm. Then I had it on about 0.6mm. And finally, it is between 0.8 to 1.0mm. The XYZ calibration didn’t work in any of these configurations.
- I checked that the zip ties for the cables exiting the extruder are firmly closed and not touching anything even while the extruder is in its outermost right/left positions in X.
- I thought maybe the new firmware has some problems in it so I made another factory reset and then downloaded and installed both: "prusa3d_fw_MK3S_3_9_0_3421.hex" (to the Printer USB-B) and "prusa3d_fw_MMU2board_1_0_6.hex" (to the MMU2 - Micro-USB)
These are from the 19th May 2020. Didn’t make a difference.
- I tried running the Calibration Wizard after bringing the X-axis all the way to the upper end of the Z-Axis with the Z: XXX function that its accessible by holding the control knob pressed after hitting the reset button. It didn’t reach the end totally and stopped at Z: 210mm. So I shut the printer down for more than 5 sec and restarted it. After restart I did the F: XXX thing again and made sure the X-axis goes all the way up until it is blocked by the ends of the Z-axis.
- I have tested the PINDA probe with homing the printer so that the probe was hovering about 2mm above and inside the little circle on the heatbed. I then checked the sensor info page and it showed “1”. I made that with all four points. I even stopped in the middle somewhere between two points and checked the sensor info. It was “0”.
- I ran the self-test several times and there where no problems besides the one with XYZ calibration.

My conclusions:
- It’s not the firmware
- It’s not an issue with the PINDA probe
- The axes are not blocked

What can I do more? I’ve read on the help page ( https://help.prusa3d.com/en/article/calibration-failed_2033 ) that there is most likely something wrong with my assembly. Before the upgrade with MMU2S it worked fine and the only thing I’ve changed in the assembly is the extruder. Do I have to reassemble the extruder?

Hint:
Not sure if it’s important but my extruder bumps into the left shaft and touches it with the lower screw of the extruder fan. It does that when its looking for reference. As well I noticed that the upper screw of the fan is not touching the shaft. It’s a difference of about 0.2mm.

I hope you can help me getting this right!

Thanks! 🙂
Simon