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Glitches in a flat layer...  

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Cranberryhiker
(@cranberryhiker)
Eminent Member
Glitches in a flat layer...

This has started happening with PETG - bed temp 85, and extruder temp 230.

It was so bad on the last part I printed, that it knocked the P.I.N.D.A. sensor out of whack.

Thoughts?

Posted : 13/11/2020 5:49 pm
Cranberryhiker
(@cranberryhiker)
Eminent Member
Topic starter answered:
RE: Glitches in a flat layer...

Another photograph.

Posted : 13/11/2020 5:50 pm
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(@)
Illustrious Member
RE: Glitches in a flat layer...

Those are probably fingerprints on the print sheet. Plain dish detergent, or dish soap and hot water will wash them away. Alcohol will just smear them around and make your life worse.

Not sure why, but some PETG sticks like superglue and you want fingerprints or gluestick or Windex, but some brands, colors, types, stick less than PLA and need a pure unadulterated print surface. No rhyme nor reason I have found, either.

This post was modified 11 months ago by --
Posted : 14/11/2020 12:38 am
Swiss_Cheese
(@swiss_cheese)
Noble Member
RE: Glitches in a flat layer...

That doesn't appear to be a dirty print surface issue to me, it looks like you have some type of blobs going on maybe snagging on the edge at one point, but I'm not sure why your having problems with the second layer not sticking in those areas, did you touch the first layer with oily fingers while it was printing?

If not maybe try reorienting the print in slicer and see if you get a different result.

The Filament Whisperer...
Posted : 14/11/2020 12:54 am
Cranberryhiker
(@cranberryhiker)
Eminent Member
Topic starter answered:
RE: Glitches in a flat layer...

Definitely didn't touch the first layer. I alcohol-wash the surface before each print, religiously. I *had*, as I said, knocked the P.I.N.D.A. sensor out of whack just before this, and while I think I did the first-layer calibration well, it's possible that I didn't.

Here's a new development - I tried to print something shortly after this one, and got what I think is called a "crash." See the video at https://photos.app.goo.gl/r7gLMYA459QWu3K69. Or https://photos.app.goo.gl/3WcvJhwAiwK5G9gQ9 ...

What's going on, here? (If it is a crash, then why?)

Posted : 14/11/2020 1:33 am
Cranberryhiker
(@cranberryhiker)
Eminent Member
Topic starter answered:
RE: Glitches in a flat layer...

@tim-m30

Alcohol - seems always to get rid of any finger-grease, for me. You're saying it doesn't for you?

Posted : 14/11/2020 1:34 am
Swiss_Cheese
(@swiss_cheese)
Noble Member
RE: Glitches in a flat layer...

well the video inst that high quality but it looks as though you have it sitting at the exact same level as the tip of the nozzle, normally you would use one of the zip ties to space the pinda a zip tie thickness above the nozzle. in the video it seems as though the pinda is hitting the print like an eraser.

this would definitely be a problem.

alcohol works fine for cleaning as a general rule, but every now and then you need to clean better then just a general IPA rub, im pretty sure thats not the problem here.

The Filament Whisperer...
Posted : 14/11/2020 1:41 am
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(@)
Illustrious Member
RE: Glitches in a flat layer...

@cranberryhiker

Here's photos from earlier prints. The bed was thoroughly wiped down with 91% isopropanol is still showing fingerprints. The skull print was washed quite well with 99% isopropyl. You judge if they are clean enough.

If you have any doubts, try the thorough soap and water wash with hot water rinse. At this point, you have nothing to lose.

 

 

 

This post was modified 11 months ago by --
Posted : 14/11/2020 2:57 am
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(@)
Illustrious Member
RE: Glitches in a flat layer...

@dan-p12

And you are wrong. Alcohol does not, as a general rule, work for everyone. If you squirt a large puddle onto the print sheet, use a large absorbent rag to quickly distribute then lift all of the resulting solution, yes, it can work. But even that doesn't clean as well as a simple hot water scrub at a sink.

Alcohol is a solvent that dissolves grease into solution, and leaves a microscopic film of oils as it evaporates; soap is a surfactant, places the grease in an emulsion that rinses away entirely.

This post was modified 11 months ago by --
Posted : 14/11/2020 3:04 am
Swiss_Cheese
(@swiss_cheese)
Noble Member
RE: Glitches in a flat layer...

well Tim, since you seem to know everything, I guess theirs no point in anyone else trying to help, but you at least should take the time to notice that cranberryhiker's problem isn't with the first layer and find a way to move on.

Enjoy and good luck

The Filament Whisperer...
Posted : 14/11/2020 4:06 am
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(@)
Illustrious Member
RE: Glitches in a flat layer...

@dan-p12

The first layer is pulling up in spots. The spots look remarkably like typical finger prints. Fingerprints propagate up through layers as the print progresses. This fouls the adhesion of the upper layers which in turn curl, generally upwards. This curl leads to collisions with the nozzle, fan shroud, or even the PINDA. Also, fingerprints are one of the most common maladies in printing, and alcohol, while it works for some, it doesn't work for everyone.  

The fact the PINDA is low may be a result of a poor initial adjustment; knocking into the curls; or, it might be the standard Mk3S extruder warp now that PETG is being printed for a while.  The video - well - it's clear the PINDA is dragging, but the root cause of that is still up in the air. 

The gap between the nozzle height and PINDA height should be 0.8 mm nominal. 

Fixing the PINDA won't fix the curling. 

Posted : 14/11/2020 4:23 am
Peter M
(@peter-m)
Noble Member
RE: Glitches in a flat layer...

Cleaning with dish soap is a lot better then with alcohol.

And yes a few prints you can clean with alcohol, but then dish soap is needed again.

And if you change filament pla to petg I would use dish soap.

Then if you print big flat model, the mk3 can not print this with standard settings(to fast), you need to print hotter or slower, the extruder will go so fast that temperature is not high enough to make a smooth layer.

Posted : 14/11/2020 7:56 am
Cranberryhiker
(@cranberryhiker)
Eminent Member
Topic starter answered:
RE: Glitches in a flat layer...

Wow - thanks, everyone for the cascade of advice! It is very much appreciated (though it did get a little abrasive, at one point, there...)

When I readjusted the P.I.N.D.A. after it got knocked a bit, I *did* do the zip tie thing. The only problem might be that I used my own, rather than one from the kit, zip tie. It might have had a thinner tongue than the "official Prusa zip ties." 🙂

So I will (re)-readjust the P.I.N.D.A., and if it is still fakakta, then I'll wash the board with soap and water (even though, if waterboarded into making a guess, I would insist that that is not the problem, here) and see how all of that goes.

Again, thank you all for your awesome support! 🙂

This post was modified 11 months ago by Cranberryhiker
Posted : 14/11/2020 1:06 pm
Cranberryhiker
(@cranberryhiker)
Eminent Member
Topic starter answered:
RE: Glitches in a flat layer...

Looks good so far. Again, thanks, folks!

Posted : 14/11/2020 2:56 pm
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(@)
Illustrious Member
RE: Glitches in a flat layer...

This is - 99.9% of the time - contaminants on the print surface.  While it might have been caused by the PINDA rubbing the print, that would have been pretty obvious to even a casual user. Since you didn't notice the PINDA crashing at this point, oils are the more likely problem. As in all remote help, it could be something else, but you go where the majority of prior experience leads.

Posted : 14/11/2020 3:59 pm
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