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I recently purchased a spool of PETG to try working with it. I have managed to dial in most of the settings in Prusaslicer but one, in particular, is giving me a problem. As seen in the photo, the clip I printed has extra extrusion on the inside and outside. I have noticed that the nozzle will pause at the seam for about 5 secs before continuing. (The bottom is not Elephant's foot, I just didn't clean off all the brim)

Photo of the front and back of a 3D printed clip showing extra extrusion

I positioned the seam on the inside of the model. I know that the extra extrusion is caused by the seam but why would it also appear on the outside of the model?

Screenshot of the Prusaslicer Preview of the model showing the seam and retractions

I have printed the same clip in PLA without any printing errors. What setting within Prusaslicer needs to change so I can get rid of the extra plastic on the inside and outside of the print?

[I don't know what relevant print settings are needed to solve this problem, but will edit the question when I get some guidance.]

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  • $\begingroup$ It's very likely just wet. PETG does awful things on resuming extrusion after retract/travel when it's wet. Unless it's been activelly dried in the past week and stored in a sealed container with fresh/dried dessicant, PETG is wet. $\endgroup$ Aug 19, 2022 at 3:11
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    $\begingroup$ Funny enough, it has been in a filament dryer for the past week. $\endgroup$
    – agarza
    Aug 19, 2022 at 4:34
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    $\begingroup$ It depends how good the filament dryer is. If it's completely closed and no air can get in/out, the humidity stays inside. $\endgroup$
    – FarO
    Aug 19, 2022 at 9:44
  • $\begingroup$ What @FarO said. There are plenty of bad filament dryers that don't actually work. $\endgroup$ Aug 19, 2022 at 18:44
  • $\begingroup$ While the idea of "wet" filament is possible, it would manifest itself over the whole model not just in one area. As seen in the photo, the front and sides of the print are fine; the area where the seam occurs is noticeably bad. But another solution was found. $\endgroup$
    – agarza
    Sep 1, 2022 at 19:51

2 Answers 2

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After checking several places online, I finally got an answer in a Discord chat.

The solution was to turn off the Power-loss recovery setting on the printer itself.

After that was done, the print came out beautifully.

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  • $\begingroup$ I just thought of that when I saw this question bumped and came here just to suggest you check that. Yep, power-loss recovery is the most horrible anti-feature on these printers. It's designed to stall the printer for a long time after unretracting but before printing by performing the (long, blocking) SD card write at the first print (extrusion+motion) move of a new layer. It's just horribly misdesigned and useless and needs to be turned off. $\endgroup$ Sep 2, 2022 at 0:11
  • $\begingroup$ @R..GitHubSTOPHELPINGICE Very true. Just another example of a great idea that was poorly executed. $\endgroup$
    – agarza
    Sep 2, 2022 at 1:07
  • $\begingroup$ Yep. Executing the idea well is rather hard though. To actually work well it'd need something like a small UPS to power the printer minus bed heater until next layer change, then pause, park the head (so the hotend doesn't sit on the print and ruin it), and record state for recovery. It also needs a printer that homes at max Z, not min Z, so that Z can be re-homed without destroying the print, and that has very good homing reproducibility in X and Y. And it needs a bed surface that doesn't release the print on cooling. And..... $\endgroup$ Sep 2, 2022 at 2:03
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Looks like Retract at layer change is causing this. Disable that and see. This will help you to improve the quality a lot.

It will be under retraction settings:

Screenshot of retraction settings

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    $\begingroup$ After disabling "Retract on layer change", the problem still exists. $\endgroup$
    – agarza
    Aug 19, 2022 at 16:52

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