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Mk3 XYZ Calibration fail - Y distance nanmm  

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cvincross
(@cvincross)
Active Member
Mk3 XYZ Calibration fail - Y distance nanmm

After 154 days of printing my Mk3 has suddenly started failing XYZ calibration. (consult manual)  support>details> lists "nanmm" for left and right Y axis distances and a skew of 0.24

firmware 3.8.1-2869

I've noticed that auto home parks the sensor about 5mm to the right of the circle.  Giving it gentle pressure makes in pop a step over and the probe aligns with the circle.  The stepper only allows for that one step of movement...but it will clunk back and forth between the correct position and the out of aligned one.

I've tried resetting the PINDA lower and higher multiple times.  This seems to effect skew but does not allow passing calibration.  I've checked the PINDA output in pronterface and there are no significant deviations.  suspected bad cable on probe... but cant make the probe flicker with flexing by hand.  

I've removed heat bed and reinstalled it carefully.

Are "nanmm" readings normal for a failed calibration?

Thanks for any help.

This topic was modified 4 years ago by cvincross
Posted : 03/04/2020 2:21 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Mk3 XYZ Calibration fail - Y distance nanmm

have you tried Lubricating the X and Y axes?

Z has less repetitive movement,  but would also benefit from lubrication in the long term 
https://help.prusa3d.com/en/article/i3-printers-regular-maintenance_2072#rods-and-bearings
regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 03/04/2020 5:03 pm
cvincross
(@cvincross)
Active Member
Topic starter answered:
RE: Mk3 XYZ Calibration fail - Y distance nanmm

I'll try lubricating.

I should clarify that this printer has been in a classroom setting outside of my direct observation.  So it is possible that frame skewing has occurred.  I'm just trying to narrow down the possibilities and rule out electronics before I tear it down and rebuild the frame.

Does anyone have input on the "nanmm" values or any other clues that might point to an electronics issue?

Posted : 03/04/2020 5:57 pm
cvincross
(@cvincross)
Active Member
Topic starter answered:
RE: Mk3 XYZ Calibration fail - Y distance nanmm

Update.

I bypassed the warnings about not being calibrated.  I was able to do a first layer calibration and got a consistent bead.  I then started a print and it appears to be level and straight.  No apparent issues.  seems to be a beautiful print.

Any ideas what could be causing the calibration to fail?

Posted : 04/04/2020 4:01 pm
cvincross
(@cvincross)
Active Member
Topic starter answered:
RE: Mk3 XYZ Calibration fail - Y distance nanmm

Resolved.

Silly me.  my brain came unplugged.  I forgot to unload the filament.  Drag from the roll was messing up the calibration process.   Oh to have the hours back 😉 

Calibration successful.  Bed slightly skewed but good enough.

 

Posted : 05/04/2020 5:39 am
cvincross
(@cvincross)
Active Member
Topic starter answered:
RE: Mk3 XYZ Calibration fail - Y distance nanmm

Resolved - UPDATE - loose X axis gear.

the actual issue was the drive gear on the X axis had worked loose enough to slip a little.  The flat side caught the movement in one direction but it would give way under any strain.  Thus my printer only passing calibration when I disconnected filament.  I would get good prints on an nearly empty roll but a new roll would fail with shifted layers.  The gear was holding well enough to pull a little weight but when there was any resistance everything failed as the gear slipped back and forth.  tightened the gear and all skew disappeared from my calibration and prints are perfect.

This post was modified 4 years ago by cvincross
Posted : 06/04/2020 5:40 pm
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