Issues printing with PRUSA i3 MK2, nozzle height and filament issue!
I just installed a replacement heatbed MK42 for my PRUSA i3 MK2, but encountering a weird issue when printing the Prusa_logo_20M. The 1st layer prints perfectly (shown below), but immediately following the infill of the rectangle—the extruder raises to begin the next layer and begins dragging the filament because the nozzle is too darn high. Why does the nozzle raise like this after the first layer prints without issue?
The first two screenshots show the initial layer is printing correctly. My Z-Axis adjustment is -0.244. The calibration gcode also printed fine, so I thought I was ready for printing. Once the first layer completes its printing and infill of the rectangle, the nozzle moves higher and then begins to extrude the filament much higher than it should. This results in the filament not sticking and will end up curling into a mess if you're not watching the printer.
The third screenshot (shown above) shows how the extrude raised its height after the initial layer. Why?
I've engaged PRUSA support on this because I'm burning a lot of time troubleshooting w/o luck. When I attempt to calibrate XYZ, the nozzle presses down hard on the bed. However, Auto Home and Bed Mesh Leveling seem to work fine and pass. Why does the XYZ calibration smash into the bed, but the actual printing of the calibration gcode file print fine?
Any suggestions? I appreciate your consideration and support! 😛
Re: Issues printing with PRUSA i3 MK2, nozzle height and filament issue!
The first thing I see is that your PINDA probe should not have this bump on its tip! So it might be a faulty probe. But if it was the only issue, you shouldn't be able to have a proper first layer...
This may be an obvious question but have you run a full XYZ calibration after the bed replacement?
Is it a genuine Prusa MK42 bed?
Do you use the gcode provided on the SD card or a gcode generated by you with a slicer?
Re: Issues printing with PRUSA i3 MK2, nozzle height and filament issue!
Great news! I believe I've uncovered the issue with my PRUSA i3 MK2. I had previously installed firmware, prusa3d_fw_3_0_12.zip and then performed factory reset, then ran the calibration XYZ. The print jobs failed after the first layer printed because the nozzle raised up and then dragged the filament because the nozzle/ extruder was too high from the build plate.
I decided to roll back to firmware 3_0_6 from last September 2016..... and that worked flawlessly. I performed a factory reset, calibration XYZ and then tweaked the live Z adjust during the V2Calibration.gcode. I then printed the Prusa logo, dual color and tested a pumpkin model from Thingiverse. The quality is perfect and everything prints as expected. Woot! 
I'm so EXCITED, but ..... a little curious as to why the firmware 3.0.12 presented problems for me. No issues after I reverted back to 3.0.6. I used the '1_75mm_MK2-RAMBo13a-E3Dv6full' for my MK2.
Anyone else have insight into this issue? Is there a bug in the firmware or some sort of setting that needs to be tweaked?
Re: Issues printing with PRUSA i3 MK2, nozzle height and filament issue!
The issue may have been corrected by the factory reset, not the new firmware.
My recommendation:
1) Do a factory reset.
2) Install the latest Firmware (make sure not to use the MMU version if you don't have MMU)
3) Do an XYZ Cal
4) Set PINDA and Live Z (as per:
5) Print from the SD card again.
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 or loss. If you solve your problem, please post the solution…
Re: Issues printing with PRUSA i3 MK2, nozzle height and filament issue!
Your PINDA probe appears worn from collisions with extruded material and i recommend you replace it.