Z axis hitting the print bed after calibration  

Re: Z axis hitting the print bed after calibration

Is the LED on th PINDA probe on when it is far from the bed?

Re: Z axis hitting the print bed after calibration

Oh woah, the PINDA led never turns on. Is there a doc page on troubleshooting the pinda sensor?

Re: Z axis hitting the print bed after calibration

You need to lower your PINDA because it is placed too high.
PINDA tries to find the bed but because it is too high, the nozzle will crash into the bed instead.

Re: Z axis hitting the print bed after calibration

I'll give lowering the sensor a try.

I'm a bit confused though, I've been printing for months without problems with the PINDA sensor level and it's aligned the way the manual shows. What would cause it to be to high now?

Also, the first time the extruder crashed into the bed it pushed the bed down probably a centimeter before the power down stopped it. I definitely understand that if the PINDA is too high the nozzle would crash before the PINDA signaled to stop, but if the nozzle was pushing that far down wouldn't the PINDA then be close enough to signal the stop?

And the sensor is extending past the nozzle tip at least a couple of millimeters or so, I would think the fact that the sensor will physically touch the bed before the nozzle would mean that the inductive signal would have a chance to fire before the nozzle actually touches the bed?

I'm also looking into why the PINDA LED isn't turning on at all now. I'm not ruling out the PINDA being too high (maybe there's part of the setup that I still don't completely understand), but the fact that the PINDA's LED used to turn on and off and the fact that it's not turning on at all now makes me suspect that it's not a placement issue (the sensor was really snuggly clamped down so I can't imagine it jiggled free and moved up/away from the bed) and more of a the-sensor-isn't-working issue.

Re: Z axis hitting the print bed after calibration

It may be that the PINDA sensor is defective or the cable has gone off.
You can check this by holding a metal part (eg a screwdriver) to the sensor. Then the diode on the sensor will be switched off. If not, PINDA may be broken.

Re: Z axis hitting the print bed after calibration

Ah cool. That makes sense. I'll try checking the sensor with a screw driver to see if the sensor recognizes it. Thanks! I'll report back in a bit.

Re: Z axis hitting the print bed after calibration

Just remembered to post back here.

I worked through with prusa support and it turns out the PINDA sensor is def the likely problem. They've shipped a new one (should be here tomorrow actually). Once it's in I'll test it and report back.

It's just tricky...

What it comes down to is the sensor has only one or two notches that put it in the correct range and then you need to fine-tune from there.  When it is calibrating, it will start high and work lower and lower until the sensor triggers (red light on the sensor).  That's when it thinks it is at Zero-Z.    If you are too high, lower the sensor one notch and try again.  If you go too low, the nozzle will bury.  Have your hand on the power switch and power-off as soon as you see scraping.  Adjust live-Z to fine-tune this and during a test print, you can micro-tune it and actually see your layers improve or get worse from the adjustments.  My first benchy was 100% pristine once I figured this out.  Hope this helps.