Troubleshooting PETG First Layer - Overextrusion?
Hello,
I've printed a ton of PLA since I've got my MK3S two years ago, but barely any PETG. I'm starting now, and I'm noticing some first layer issues.
I'm using:
- Textured Sheet (Z Adjust is -0.975, compared to the Smooth Sheet -0.700)
- Filament: Fiberology Easy PETG
with this first layer settings:
- Bed Temp: 85
- Nozzle Temp: 240
- Speed: 20mm/s
- Height: 0.2mm (nozzle is 0.4mm)
I'm attaching a picture - These two first layers printed together side by side. I think the Z height looks good, but I'm not sure if there's something about the temperature, speed, or something else that might be causing this.
Note that i had already removed them from the sheet and put them back there for the pic. I didn't print at a weird angle.
Any ideas? 🙂
RE: Troubleshooting PETG First Layer - Overextrusion?
Hard to say for sure…
The z height looks good from your pics. If you can post a pic of the bottom of one of the prints, that would be helpful.
For me, with PETG, shiny means hotter temps. Maybe try a first layer at 10* cooler and see what you get. Those ‘bubbles’ almost look like hot-spots.
Have you dried your filament? They could also be the result of moisture boiling off during the print.
Cheers
RE: Troubleshooting PETG First Layer - Overextrusion?
I don't think it's overextrusion, that would cause more regular artifacts. Is it possible the material is coming from somewhere else? Did you check your hot end for leakage?
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RE: Troubleshooting PETG First Layer - Overextrusion?
That looks like a patch of oil/grease on the bed. You get raising like that when you have contaminants on the bed and the filament doesn't stick in that area.
RE: Troubleshooting PETG First Layer - Overextrusion?
Thanks for all the tips! I've raised the nozzle a bit (to -0.950) and the problem has disappeared. I kept everything else the same, but I now realised I was printing with Prusament PETG temps instead of the Fiberology recommended ones (as per the Prusa Slicer default profile), so I also changed it as well, to extrude a bit cooler.
RE: Troubleshooting PETG First Layer - Overextrusion?
Also, PETG is more likely than PLA to curl back and stick to the nozzle/heater block. This can lead to more accumulation of crud which can then drop down at unexpected times to cause artifacts like the one you're seeing.
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RE: Troubleshooting PETG First Layer - Overextrusion?
yes.. too hot.. and I think Neophyl's advice sounds like it could be the issue.. some contaminant.. clean with soap/water well. For some reason, I find that both the smooth and the rough need a good scrubbing of dish soap & water occasionally. IPA won't always work as well.
RE: Troubleshooting PETG First Layer - Overextrusion?
After a few more tries, where I applied all your suggestions (Cleaning the bed well, lowering the temperature) it's working great now!
So I guess it was a combination of it all? 🙂
Thanks everyone again! <3