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Textured Sheet First Layer Issues with PETG.  

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khyzersoze
(@khyzersoze)
Eminent Member
Textured Sheet First Layer Issues with PETG.

I've been printing with the textured sheet and PETG for over a year with good results and no issues, until a print went bad and caused a cascade of issues that ended up with me replacing the hot-end.  Anyway I replaced it and ever since then I can't get the same results for the first layer on the textured sheet with PETG that I did before.  I am using the same brand of PETG, same textured sheet.  I've cleaned the sheet, re-calibrated the Z and have it on 7x7 leveling.  When I do the first layer calibration everything looks fine.  It's at the point where I can't go any lower on the Z without risking hitting the sheet or ripping the layer.  During this time there might have been a slicer update, so it's possible maybe that had an effect as well.

In the picture below you can see the results that I was previously getting before on the left and on the right are the results that I'm getting now.  I can't seem to get the same smushed textured look anymore.

I am using Generic PETG settings and the Quality 0.15 Setting.

Anyone got any ideas of what I can be missing?

Posted : 02/02/2022 3:38 am
kpreid
(@kpreid)
Trusted Member
RE: Textured Sheet First Layer Issues with PETG.

That looks like the usual nozzle too high for the first layer. But you say you've adjusted it down. Some hypotheses:

  • Under-extrusion, so the height is right but not enough plastic is going in to make it squashed wide enough.
  • Somehow the gcode is directing the extruder to start higher up than it does during calibration.
  • Generally, wrong slicer settings / wrong printer profile. Have you reset the print, filament, and printer settings to all Prusa default profiles?
  • Your PINDA's temperature sensitivity is causing the print to turn out differently than the calibration.
  • It's actually not set low enough.

Could you post a picture of the square the first layer calibration routine prints (top while it's on the printer and bottom after peeling it off)?

Posted : 02/02/2022 3:58 am
khyzersoze
(@khyzersoze)
Eminent Member
Topic starter answered:
RE: Textured Sheet First Layer Issues with PETG.

I will see if I can get a picture of the first layer calibration for you tomorrow.

Posted : 02/02/2022 8:57 am
khyzersoze
(@khyzersoze)
Eminent Member
Topic starter answered:
RE: Textured Sheet First Layer Issues with PETG.

As promised, here is the first layer calibration results with my current z settings.  The same z settings for the print on the right side in the first post.  Other prints that I have done with no issue before are now having the same issues using the same GCODE that I was using before.

Posted : 02/02/2022 4:25 pm
kpreid
(@kpreid)
Trusted Member
RE: Textured Sheet First Layer Issues with PETG.

Interesting! The top surface of your first-layer swatch looks nicely fused, but the bottom isn't meeting. I've never had that happen. Maybe the extruder temperature is too low and the plastic doesn't flow like it should? I've got no good ideas and maybe someone else has one.

Posted : 02/02/2022 4:31 pm
Bob
 Bob
(@bob-2)
Reputable Member
RE: Textured Sheet First Layer Issues with PETG.

Your z-offset is too high.  Not by a lot, but still too high.  I'd try lowering it by -0.050 and try again.

Regards

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit, Prusa I3 Mk3s+ kit

Posted : 02/02/2022 4:56 pm
khyzersoze
(@khyzersoze)
Eminent Member
Topic starter answered:
RE: Textured Sheet First Layer Issues with PETG.

Alright Here is the First layer lowered by -0.050

Here it is lowered by  -0.055 from original

Here it is lowered by -.1000 from original

 

Lowering it by -.1 does indeed make the bottom look better, but it makes the top look like it's faded/scraped?  I think it'll print fine, because it was sort of like this previously.

I did try having the z this low before, but it caused issues for prints that took up more area of the sheet.  For smaller prints it was fine.  This was when I had it at 3x3 leveling though.  I now have it at 7x7 and maybe it won't be an issue anymore.

I'm currently testing out a small print that only takes up the middle of the sheet with the additional -.1 setting to see if the bottom turns out how I like.  Afterwards I will try multiplying the object and printing across the plate to see if different areas of the sheet are still an issue.

 

Posted : 02/02/2022 7:18 pm
Bob
 Bob
(@bob-2)
Reputable Member
RE: Textured Sheet First Layer Issues with PETG.

What you are aiming for is to have that little rectangle to be a solid flat sheet of plastic.  When you're too high there are gaps or trenches between the filament strands, when you're too low there are ridges between the filament strands.  Your last two photos look like your damned close, you could take it down a little bit more, but keep your increments around -0.025 to -0.50. 

If this were mine I'd dial it down just a touch more, but right now you're really really close.

As for the top appearance looking faded or scraped, who really cares?  This is all about good first layer adhesion, that first layer will get 3 or more full layers on top before it even starts with infill so you'll never see it. 

Cheers

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit, Prusa I3 Mk3s+ kit

Posted : 02/02/2022 8:10 pm
khyzersoze
(@khyzersoze)
Eminent Member
Topic starter answered:
RE: Textured Sheet First Layer Issues with PETG.

Thanks Bob.  Once I get this dialed in, I want to see what the behavior is when printing across the whole plate.  Of course, that is a different issue altogether if I'm getting different results at each part of the plate.  Hopefully the switch to 7x7 leveling from 3x3 helps with that.

Posted : 02/02/2022 8:36 pm
jsw
 jsw
(@jsw)
Famed Member
RE: Textured Sheet First Layer Issues with PETG.

For the textured sheet, I'm in the habit of tuning the Z just to the point that the 'brush strokes' blend in to the texture.

Posted : 02/02/2022 8:42 pm
khyzersoze
(@khyzersoze)
Eminent Member
Topic starter answered:
RE: Textured Sheet First Layer Issues with PETG.

I guess what threw me off is that if you looks at my initial live z calibration patch, and the printed part on the right of the first picture, you would not guess that they were both printed at the same z-height.  It looks drastically different in terms of level of smush against the sheet.

Posted : 02/02/2022 10:09 pm
khyzersoze
(@khyzersoze)
Eminent Member
Topic starter answered:
RE: Textured Sheet First Layer Issues with PETG.

So it looks like I did indeed still have the z up too high and lowering it helped with print adhesion as well as having a nice textured pattern.  Thanks guys for helping me determine that I still had a bit more to lower on the Z.

Of course..... I had to just run into another issue shortly afterwards....

https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-general-discussion-announcements-and-releases/holy-layer-shift/#post-574744

Posted : 03/02/2022 6:06 am
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