Notifications
Clear all

Z Calibration Drifting?  

  RSS
Ke88
 Ke88
(@ke88)
Active Member
Z Calibration Drifting?

Hello All,

Had my Mk3s+ for ~6 months.  Really nice printer.  I've run into an issue that I suspect is a failing PINDA probe, but I was hoping to get some validation/ideas of other sources.

The problem is that when I start a print, occasionally the printhead will be printing much much lower than the print that just completed.  I initially did the live adjust such that the offset was around -1.5mm (quite large I know), which worked great for ~5.5 months.  Then suddenly one print was digging into the bed which caused me to raise that offset to about -1.0 to get a good first layer.  Again, last night I start a print and the same thing happens causing me to raise the offset to -0.3mm.  No other settings changed, same slicer, same settings, etc.  I am running PrusaSlicer through RepetierHost and the print is being executed by RepetierServer, FW version is 3.9.3-3556.

As I mentioned, I suspect the PINDA probe is starting to fail, which I gather can happen.  Does anyone have an alternative explanation or anything to check?

Thanks for reading

 

Posted : 23/09/2021 1:28 pm
cwbullet
(@cwbullet)
Illustrious Member
Drift

A slow drift can be normal but it should slow to near nill change.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 23/09/2021 2:07 pm
Ke88 liked
Ke88
 Ke88
(@ke88)
Active Member
Topic starter answered:
drift

So a drift of half a mm in between prints is atypical?

Posted : 23/09/2021 2:36 pm
bobstro
(@bobstro)
Illustrious Member
Not normal, but may not be PINDA failure
Posted by: @ke88

So a drift of half a mm in between prints is atypical?

Definitely not normal. I'd make sure the PINDA probe isn't loose or moving before making too many replacements. Also check to make sure the support arm holding it is aligned properly and not sagging. Depending on the age of your printer, some of the earlier design revisions were prone to sagging.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 23/09/2021 2:42 pm
Ke88 liked
Ke88
 Ke88
(@ke88)
Active Member
Topic starter answered:
R: Not normal, but may not be PINDA failure

Interesting.  I attempted to wiggle it after the first shift and it was very secure, however I will double check.  As for the age:  I purchased it around April or so.  Not sure if that pre-data any major design changes.

Posted : 23/09/2021 2:47 pm
cwbullet
(@cwbullet)
Illustrious Member
push

I would gently push it from the bottom and not pull on the wires.  

Posted by: @ke88

Interesting.  I attempted to wiggle it after the first shift and it was very secure, however I will double check.  As for the age:  I purchased it around April or so.  Not sure if that pre-data any major design changes.

 

--------------------
Chuck H
3D Printer Review Blog...
Posted : 23/09/2021 3:04 pm
bobstro and Ke88 liked
Zorro_X
(@zorro_x)
Eminent Member
Similar problem here

Hi, it is interesting, I have a similar problem here ( https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/first-layer-flow-problem/ ) but in the opposite way : Z-Axis seems too high each new print (?!)

Posted : 23/09/2021 3:44 pm
Ke88 liked
bobstro
(@bobstro)
Illustrious Member
SuperPINDA or PINDA?

Is yours a PINDA or SuperPINDA probe? Just to confirm: If you let the printer cool off completely between prints, do you still get the same problem? Conversely, if you lower the nozzle close to the bed and warm it before a print, do you still experience drift? The PINDA v2.1 and SuperPINDA were supposed to eliminate temperature variability, but I've been contacted by owners of both asking for help modifying the 2-step warmup procedure I've documented here

If the behavior of yours has changed, it's most likely a failing probe, but this is worth a check.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 23/09/2021 4:27 pm
Ke88 liked
fuchsr
(@fuchsr)
Noble Member

I've seen this a few times. Each time it was the PINDA loose in its holder. Didn't feel like it when I wiggled it but a quarter turn of the screw that holds it in place fixed it every time.

Posted : 23/09/2021 7:22 pm
Ke88 liked
Ke88
 Ke88
(@ke88)
Active Member
Topic starter answered:
A few leads

Hi All,

I checked the holder and apparently the screw has wiggled out.  I resecured the probe and will run a recalibration.  If this solves the problem I will feel quite foolish 🙂  The only thing is that if the sensor was loose I would expect it to slip downwards which would result in sensing the bed higher up which would result in the first layer being higher not lower... More testing needed to see if it fixes the problem.

I'm pretty sure it's the SuperPINDA. 

 

Thanks for all the help so far guys!

Posted : 24/09/2021 2:11 am
Dan Rogers
(@dan-rogers)
Noble Member
Doesn't cost anything to just make sure it's tightly screwed in.

Makes total sense that it would drift closer - or further with a loose probe.  Imagine the probe slipping down enough to hit your print late in the print - it will knock the sensor higher.  Then it slips down and hits at another time... up and down we go.  Just tighten the screw and don't over-think it.

Posted : 24/09/2021 10:18 am
bobstro liked
bobstro
(@bobstro)
Illustrious Member
Great diagnostic check!
Posted by: @dan-rogers

Makes total sense that it would drift closer - or further with a loose probe.  Imagine the probe slipping down enough to hit your print late in the print - it will knock the sensor higher.  Then it slips down and hits at another time... up and down we go.  Just tighten the screw and don't over-think it.

That's a great explanation and a good diagnostic check. If it only goes lower and is not random, check out mechanical issues.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 24/09/2021 4:04 pm
Ke88
 Ke88
(@ke88)
Active Member
Topic starter answered:
So far so good...

Hello all,

I reset the PINDA height and re-ran all calibration steps and am printing fine now.  I will watch for this behavior in subsequent prints and report back if it crops up again.  Thanks again all 🙂

Posted : 25/09/2021 10:42 pm
Share: