Settings for print with PETG

  • Hi,

    i know that this question its not for this forum, but i post here if someone, can help me.

    Since 1 week aprox. i am triying to print in PETG... but i have problems, when for print the piece, the nozzle do not have to make movements in a vacuum, the piece prints well. I have to say that it is a material that I like very much ...

    But ... when I try to print several pieces, or a piece with two bodies, that the head has to make movements in a vacuum, it gets stuck. I suppose it will be because of the configuration of the retraction.

    Can someone tell me what values do you use?

    Thank you

  • Are you using a direct or bowden setup?
    What retraction length and speed are you using? (pressure advance?)
    What temperature?

    I could only ever acheive a clog with pet-g when I used way too high temp (270 C), in this case I could see clear signs of discoloration on the printed part aswell.

    BTW, I use
    -240 C
    -FW retraction of 3mm at 100mm/sec
    -pressure advance of 0.3s (I use a long, ~75 cm bowden setup)

  • I've done a fair bit of testing with E3D Edge which is a type of PETG, as well as Taulman T Glass and other generic PET-Gs. They are all a bit different but in general I have found that the higher the print temperature, the more "stringy" they become. I generally use the lowest temperature that I can get away with which is in the region of 220 degC on my machine but varies a bit depending on filament type. I also have to use an extra mm of so of retraction.

  • @denke said in Settings for print with PETG:

    BTW, I use
    -240 C
    -FW retraction of 3mm at 100mm/sec
    -pressure advance of 0.3s (I use a long, ~75 cm bowden setup)

    I note that you are using a highish amount of pressure (I need 0.5 with my Diamond hot end). Just out of curiosity, do you have any problems printing circles or arcs? If so, may I ask what slicer you use? The reason I ask is that, although I really would like to use pressure advance, I've had to disable it because I get all sorts of erratic movements when doing arcs of any kind with pressure advance enabled.

  • How fast are your travels? Zhop? Wipe on travel?

    Is the filament new? PETG can get stale and take on moisture. Maybe try a fresh roll or try drying it.

    There are a couple other thread about petg printing tips. Try the search.

  • The high pressure advance value will reduce the amount of retraction needed. It sounds like it may be getting pulled too far up and during a longer travel move it has a chance to cool and solidify causing the jam.

  • @phaedrux said in Settings for print with PETG:

    The high pressure advance value will reduce the amount of retraction needed. It sounds like it may be getting pulled too far up and during a longer travel move it has a chance to cool and solidify causing the jam.

    It's Denke and I (sometimes) that are using high pressure advance but we're not the ones having problems - no idea if the OP is using it, he doesn't say.

  • Ah yes. Reading comprehension impaired due to fatigue and reading on a phone while eating in hospital cafeteria. I should probably not bother but the distraction is nice.

  • @deckingman
    Yes, I need to use quite high pressure advance because of the long bowden setup.

    -Custom Delta for 1.74
    -Duet Wifi
    -Smart Effector
    -Olssen Ruby 0.4mm
    -Bondtech-style extruder (self made)

    I get much better results with pressure advance and circles:
    Yesterday I printed three tubes simmultaniously with 5mm outer and 3mm inner diameter (for idler roller shaft size conversion 🙂 ) and it came out the best with the following settings:
    -Firmware retraction - 3mm with 0.1mm extra advance on unretract, 150mm/sec speed
    -Pressure advance of 0.3 ... 0.4 (at 0.5 it gets very loud)

    I use cura 3.3.1 under linux,
    -I had to add "Printer Settings" plugin to enable firmware retraction
    -Coasting off
    -240 deg for pet-g
    -65 deg bed
    -45mm/sec wall speed
    -120mm/sec infill speed
    -250mm/sec travel speed

    Did I miss anything?

  • Hi,

    Thanks for comments, In this moment is printing... Really, I don't know why.

    I have change slicer, in this working print I am using Cura 3.8.1...

    This supposes that it is a problem of the configuration of the slicer ... Then I will look for the differences ...

  • @denke

    Thanks. May I also ask whet version of firmware you are using?

    I use Slic3R which occasionally, creates uneven segment lengths for arc moves. Normally this doesn't affect the print unless I try to use pressure advance. It seems that these random odd segment lengths trigger pressure advance to happen when it shouldn't. I didn't get this behaviour with older firmware, which is why i asked what version you are using.

    @peirof Sorry for hijacking your thread.

  • @deckingman
    I use the latest 2.0 stable release.

    I'll add that true, the results were much better with pressure advance, and resulted in a suprisingly strong part, the inner and outer surfice was far from perfect. I accounted this to the extremely high retraction count per printed length ratio.

    I remembered that you posted a youtube link once, and re-checked.
    Aaaaaand .... you have a very cool printer!!

  • @denke

    Thanks. I have to say that I love what pressure advance can do - it's just this issue with curves that I have. It looks like I'll have to find another slicer but none that I've tried so far can deal well with multiple machine profiles and firmware retraction and 5 extruders. The latest version of Cura is about the only one I haven't tried - I'll give that a go when I get time.

  • @deckingman
    Happy hunting!

  • @deckingman cura requires a plugin called printer settings to enable firmware retraction. You can also input your speed settings and the print time estimates will become accurate.

    Overall I like Cura better but it takes a lot more settings tweaking to get it really dialed in. Even then it can do some bizarre things.

    No experience using it with multiple colors

  • @phaedrux Thanks. I've got a very old version of Cura which I gave up on but I haven't tied the later versions. The other one that's on my list to try is Kissslicer, but it only supports 4 extruders and even then only with the paid for version. I like to "try before I buy" (learned that lesson with S3D but I did eventually get a refund).

    TBH I'd much prefer to stick with Slic3R but for pressure advance to work for me, I'd have to revert back to using a version of firmware around 1.17 or 1.18 - that was much more tolerant of less than perfect gcode files.

  • @deckingman said in Settings for print with PETG:

    @phaedrux Thanks. I've got a very old version of Cura

    Cura changed a LOT, and recently.

    I'm using the "latest", and many, many times (after setting a decent printer profile) I can just "accept all defaults" and get a great print. Some specialty stuff, like 1 layer thinwall for RC airplanes, requires a bunch of settings. But most prints... use the new summary gui, click one or two basic things, and print.

    Its not magic, and its not perfect... but it has evolved a lot in just the last few months.

  • @deckingman I'm curious, were you using the detect thin lines option in Slic3r? I've found that it can break up lines more than you'd expect when trying to vary the line thickness below nozzle width. Sometimes it works out great and combines two lines into a thicker line of gap fill, other times it utterly ruins a print. I could see the way it breaks up lines playing Havok with pressure advance.

  • @danal agreed. The version 3 series of Cura has really improved. My biggest complaint is the GUI performance is pretty poor for me. And occasionally certain models will take an extremely long time to slice with some of the optimization settings enabled.

  • @phaedrux said in Settings for print with PETG:

    @deckingman I'm curious, were you using the detect thin lines option in Slic3r? .......................................

    Quick answer is no.

    Longer answer is that what Slic3R does is random - or at least if there is a pattern to it, I haven't been able to fathom it. I have a test piece which is simply 10 cylinders of different sizes. When it's sliced and I look through the gcode file, for 95% of the layers it's fine and every segment for any given circle is the same size. But, every now and then there will be one circle which has a larger segment, followed by one or more small segments. That "pattern" may repeat for a few moves then resort to every segments being the same size. It doesn't happen on every layer, nor does it happen on the same cylinder every time. I might get 2 or 3 layers where every circle is fine with no odd size segments. On the next layer, one or more of the cylinders will have uneven segment sizes.

    It's hard to spot unless you know what to look for, and doesn't show up under normal printing - the difference in segment size isn't that great. It's only when I enable high pressure advance that I get problems trying to print it.

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