MK2S ZYZ Calibration Fails (Nozzle digs into bed)
Hello,
I recently built the MK2S from a kit and am having issues with the XYZ calibration step. The self test passes successfully. Basically, when I start the XYZ calibration step, the nozzle slowly descends towards the print bed with each pass but it never stops when it reaches the bed. The first time I tried this, I didn't catch it in time and the nozzle continued to dig deep gouges into the print bed and I had to manually cancel it. I've tried to readjust the height of the PINDA probe, so that it's slightly higher or lower than the thickness of a zip tie, but it doesn't seem to make any difference. Even with the height just a hair higher than the nozzle, it doesn't stop. Could anyone tell me what the issue may be?
Re: MK2S ZYZ Calibration Fails (Nozzle digs into bed)
Your approach to lower the pinda sensor is sound. Too bad it didn't help 🙁 The sensor has roughly a detection range of slightly less than 1 mm i was told - some a bit more, some a bit less. Prusas ziptie fetish is nice and all, but as a reference for the mounting height of the PINDA probe, i think "zipties" is a strange unit to measure in.
Anyway, try a simple test first: when you look at your PINDA probe, you should see a faint red light (might have to dim your lights int he room to actually see it) The light needs to go off, it metal (iron, steel, something magnetic) is present in the sensor range (i.e. a screwdrive). Is that working?
Re: MK2S ZYZ Calibration Fails (Nozzle digs into bed)
Thank you very much for your response and suggestion. I was able to confirm that the PINDA sensor appears to be working. Its red LED is on and it does turn off when it's near a metal object. After working with Lucas from chat, and doing some additional tests, it seems like there may be an issue with my Y axis assembly or motor.
The autohome function doesn't work properly and is offset on the Y axis. Also, sometimes the Y axis motor can move forwards but can't reverse. The self test was passing at the time that I wrote this originally, but now it's failing at the Y axis step. It looks that may be causing the XYZ calibration step to fail since it's not scanning in the right area, if I had to guess.
I put together some videos for support to review. My best guess right now is that maybe the Y axis stepper motor is faulty or maybe my Y axis assembly has some some sort of issue.
Re: MK2S ZYZ Calibration Fails (Nozzle digs into bed)
Did you find the problem with the PINDA? I am having similar problems, and cannot seem to get a good compromise with the PINDA height. When I lower it, the z height goes way past -1 to get a half decent first layer; If I raise it slightly, the extruder head catches on the paper placed onto the bed when calibrating. If this is a fault with the PINDA, the the support at Prusa should know and send a replacement, but they seem to take forever to respond. At this rate, the printer will be out of date by the time I get it printing anything. The technology will have moved on ...
Re: MK2S ZYZ Calibration Fails (Nozzle digs into bed)
I worked with Prusa support and they were able to identify that I had a defective Y end stop. I was sent a replacement end stop and now the XYZ calibration step, autohome, and self test all pass successfully and consistently. I suspect that the problem with the XYZ calibration was that it wasn't scanning in the correct area before, due to the issue with the end stop. The PINDA sensor and its alignment were actually fine in my case, and I didn't need to make any additional changes there.
Re: MK2S ZYZ Calibration Fails (Nozzle digs into bed)
Do you know why the self test did pass while you had the defective endstop? IMHO it should fail then.
Re: MK2S XYZ Calibration Fails (Nozzle digs into bed)
The issues that I was having seemed to be very intermittent. In addition, I wasn't getting very consistent test results at all, so it's hard to make sense of exactly what happened. At first, the self test was working fine, then the XYZ calibration failed, and then I found later that the self test started failing. It's hard to say what was going on. Everything has been working perfectly after replacing the defective Y end stop, though.