I have started printing with PETG so I can create objects that won't deform if I leave them in my car.

My first prints look good, but have strings of material coming off the print in places.

What should I try to prevent that?

I haven't had this problem with PLA.

  • 3
    $\begingroup$ Can you attach an image? $\endgroup$ – Davo Aug 21 '17 at 13:16
  • $\begingroup$ I know PETG by nature strings a bit. You may want to increase the temperature in the room, or add an enclosure. I think when the hot end pulls away from the piece, the material is instantly hardening causing the stringiness, maybe increasing the environmental temperature will allow the filament to release from the work piece before it hardens into a stringy mess. $\endgroup$ – ctilley79 Oct 15 '17 at 21:28
  • $\begingroup$ Would turning off the fan that cools the filament (not the print head) accomplish the same goal of slowing down the hardening of the PETG? $\endgroup$ – Gdalya Oct 16 '17 at 23:55

I've had similar experiences switching from PLA to PETG, and haven't gotten it fully figured out yet.

From what I know so far, to reduce petg strings:

  • Increase retraction
  • Lower temperature
  • $\begingroup$ Thank you for your input. I spoke to a friend at work, and he said that he saw online somewhere that what you need to do is to adjust your temperature until you can just push through the filament by hand. He got good results printing at 250, whereas I was at 240 on a printer similar to mine. However, he also said that the exact temperature varies from printer to printer and also each spool of PETG may be different. $\endgroup$ – Gdalya Sep 15 '17 at 21:40
  • $\begingroup$ That sounds like good advice to me, thanks for sharing it! $\endgroup$ – ctag Sep 16 '17 at 1:12

If you are using a printer that runs Marlin, you might consider upgrading to a version with Linear Advance. Once I started using Linear Advance, I reduced the stringing of PETG. Also I was able to reduce the retraction amount without reducing the quality of the prints.

  • $\begingroup$ Thank you. How do I tell if my printer runs Marlin? $\endgroup$ – Gdalya Oct 16 '17 at 23:52
  • $\begingroup$ well , what printer do you have ? $\endgroup$ – Kotiq Oct 17 '17 at 0:13
  • $\begingroup$ Keep in mind that Linear Advance was added this year in the Marlin firmware . I also did a temperature tower print , and ended up lowering by 10 degrees the print temperature. You can start by doing that , before you start changing the firmware on the printer :) $\endgroup$ – Kotiq Oct 17 '17 at 0:15

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