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Nozzle way above bed (first print calibration).  

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RGH
 RGH
(@rgh)
New Member
Nozzle way above bed (first print calibration).

Just finished by Mk3S+ build. XYZ calibration Wizard went fine. However, on the first layer calibration print, the nozzle is a good 1-1.5mm above the bed. Far far more than can be corrected. The extruded PLA can be seen to fall down onto the bed (and eventually gets caught and blobs up on the nozzle.

I've adjusted the PINDA sensor at least 3 times, that didn't help. I manually adjusted the Z screws a couple of times (i.e. last instructions in kit build) The nozzle is consistently the same 1.5mm above the bed.

The handbook talks a lot about the nozzle hitting the bed, but not the opposite problem!

Although this is my first Prusa, I've used other 3D printers in the past.

(In case someone asks ... no I didn't have the steel sheet on for the very initial 4 point calibration. I used a normal piece of paper ... not sure what else I could have missed).

 

Thanks!

 

RGH

 

Posted : 17/02/2021 5:12 pm
hli
 hli
(@hli)
Trusted Member
RE: Nozzle way above bed (first print calibration).

The range for a Z correction is 2mm downwards. This is measured from the point where the PINDA sensor detectds the bed. If you already set the Live-Z to -2.0mm, your PINDA sensor is too low and needs to be higher.

Posted : 17/02/2021 5:30 pm
Dan Rogers
(@dan-rogers)
Prominent Member
RE: Nozzle way above bed (first print calibration).

During your calibration print, did you use the button on your control panel to shift to "adjust live-Z"?  You didn't mention whether you tried any adjustment after your manual calibration.  In case you did not know about live Z, once your calibration print finishes the nozzle wipe, click the control button once, and scroll down to the adjust live-z setting, and click the button once the cursor is resting there.

That activates live-z setting - and you should see your current nozzle height as zero.  To move the head closer to the bed as the calibration starts, turn counter clockwise rather aggressively (given the distances you are observing) .  A value of -500 is .5mm closer to the bed, and so on.  If you are far away, don't have to spin slowly.  During your first cal, your goal is to get the head zeroed in on the bed surface while it is traipsing around the bed.  As it gets to the square in the closest leftest corner, you want to start zeroing in on a good squish.

 

Posted : 17/02/2021 6:30 pm
RGH
 RGH
(@rgh)
New Member
Topic starter answered:
RE: Nozzle way above bed (first print calibration).

@hli, @dan-rogers

Thanks. It looks like I had two problems, one, my PINDA might have been a little too low. (I had tried raising it up before, but I then got the fail-to-detect error. This time it was just a tiny squeak of a raise.).

However, the real problem is that I simply did not have enough time while it was trailing around the bed to lower it down enough. I was whizzing around the dial but obviously, I didn't want to go too fast, lest I run into the bed!

Anyway, I think I've dialed it in now. Now I'm trying to deal with the fact that none of my computers has an integrated SD Card reader (writer!). (Do any, these days?). I'm digging through old boxes to find the one I bought in 2002!

Posted : 17/02/2021 6:41 pm
Dan Rogers
(@dan-rogers)
Prominent Member
RE: Nozzle way above bed (first print calibration).

@rgh

I bought one on amazon - they're super cheap and plug into SD port.

Posted : 17/02/2021 6:43 pm
hli
 hli
(@hli)
Trusted Member
RE: Nozzle way above bed (first print calibration).
Posted by: @dan-rogers

@rgh

I bought one on amazon - they're super cheap and plug into SD port.

An SD card reader for the SD card slot?

Posted : 17/02/2021 7:13 pm
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