3D Printing Request for help with PETG

Discussion in '3-D Printing and Related topics' started by Charles_McG, Mar 5, 2019.

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  1. Mar 8, 2019 #31

    cwbullet

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    You might be right. I just used slic3r to slice it and print it and it came out dead near perfect.
     
  2. Mar 8, 2019 #32

    Charles_McG

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    So it can be done. With the settings you list above? Retraction? seam alignment? Z hop? Fan?

    Could you send me the gcode file do I can compare it to Cura?
     
  3. Mar 8, 2019 #33

    cwbullet

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    I used the stock SLIC3R settings with the changes I listed above and a 10mm brim. That is all.
     
  4. Mar 9, 2019 #34

    Charles_McG

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    Thanks for the file, Chuck. Alas, Cura makes hay of it, even when set to a Prusa.

    I had the wall thickness set to 3 layers, and I noticed that Cura was inserting a tiny dab of inner wall under each lower rail. That forced a transverse movement while everything else was around the perimeter.

    I moved down to 1 wall thickness and Cura does the same number of passes, but with different movement. Much improved - still some strings, but easily file-able.

    I’m still having trouble with PET stringing on inside surfaces. Outer look great.

    I manually played with temp and fan during a print, to no effect other than making brittle spots.

    I love the way PET feels, but not the way it oozes.
     
  5. May 2, 2019 #35

    Charles_McG

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    So, I found an article on improving PETG prints that laid out the reasoning for various settings. And it’s made some improvements, but hasn’t fixed it entirely.

    The authors main argument was to avoid over-extruding. Avoid the pile up of melted filament accumulating on the nozzle. Raise the live Z. Thicker layers. Reduced flow adjustments. And, I’ve certainly seen a reduction in surface blobs - on the print and way down (but not gone) on the print.

    But the inside of the print is still stringy. As seen below. The only time it wasn’t was when I forced outer shell before inner shell. But that print was bad, I think because I had set too much retraction and extrusion started late and spotty.

    It always oozes so much after stopping. I have the extrusion tuned for wall thickness- I wonder how much I can turn it down? And maybe reduce the infill speed - it looks pretty high.

    The only suggestion I can’t implement in Cura is a 5mm wipe at the end of a layer. Cura limits you to 2x the nozzle diameter.

    View attachment 381618
     
  6. May 2, 2019 #36

    mpitfield

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    Have you tried another brand of PETG? If you send me the file I will print it using my PETG as a comparison.
     
  7. May 2, 2019 #37

    Ian A Dalton

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    I’ve struggled with PETG for months. I’ve done hours and hours trying to get usable prints. Most of my prints are utilitarian so I’m not looking for flawless, but simply useable. Right now I have useable prints from eSun Grey PETG. I have aCR-10s and I use Cura. Here are my main settings:

    E Temp: 245
    Bed Temp: 90
    Print Speed: 30 - 50 depending
    Retraction Distance: 6.5
    Retraction Speed: 60mms
    Combing: Off
    Fan: 50% after first layer
    Enable Coasting: Yes

    This has been a VERY frustrating journey but I think I am at a workable place. I still get strings and some are pretty bad but I can make it work for a few prints before I tinker again to dial things in.
     
    Last edited: May 2, 2019
  8. May 5, 2019 #38

    gorillamotors

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    Could you send a link to the article.
     
  9. May 8, 2019 #39

    Charles_McG

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  10. May 8, 2019 #40

    manixFan

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    Great link, thanks for that. Interesting that he does not recommend switching between PLA and PETG using the same nozzle. I do that routinely and now may have to rethink it. I've through the Slic3r manual and it does a good job of explaining the settings, but of course it does not say how they should be adjusted for different filaments. And not all slicing software uses the same terminology or even has the same number of settings.

    'Plug and play' this ain't!


    Tony
     
  11. May 8, 2019 #41

    Charles_McG

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    Indeed. I use Cura and some of the settings people mention (like the avoid crossing walls) don't seem to exist. Others have hard limits. For instance, this article mentions increasing wipe a large value (5mm). But Cura won't let you set more than 2X the nozzle (0.8 for me). I'm slowly learning that some settings hide underlying problems. When I unintentionally turned off random layer start point, I found I was over-retracting. The slow start to print was more obvious when it was aligned and stacked. I'm looking at coasting now - eyeing it like a calibration. The default Cura setting is 0.064uL. Well, the worm that self-extrudes after a print is done is about 3uL (0.45mm x 13mm) - that suggests I've got a lot of wiggle room to experiment.

    I think I still need to practice getting the Z set. I watched that blob build up on last night's print and knew it wasn't good. Mess that up, and the other things matter less.
    I need a good test print that I can do in 30-60 minutes. The tower torture test with all those short movements isn't very representative of what I actually print.
     
  12. May 8, 2019 #42

    cwbullet

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    Three things I have learned from my Prusa with PETG -
    1. never let it cool all the way down (damage to print surface).
    2. Windex aids with removal.
    3. The perfect Live z is essential to getting a good first layer.
     
  13. May 10, 2019 #43

    mpitfield

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    CHEP just uploaded a new video on PETG using his slicer of choice, Cura. Anyone having PETG issues might get some good info or tips from this.

     
    Bill Hanson and cwbullet like this.
  14. May 10, 2019 #44

    cwbullet

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    Great video!
     
  15. May 11, 2019 #45

    mpitfield

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    I need to try that neon green Prusament PETG.
     
  16. May 11, 2019 #46

    jbr

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    I print all my parts with PETG, no issues
     
  17. May 11, 2019 #47

    cwbullet

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    I have tried orange and black. I may order neon green in July if they start selling the new beds.
     
  18. May 12, 2019 #48

    Charles_McG

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    I saw this post earlier in the day, while googling. I tried the lower retraction speed, and sure enough, it reduced stringing and the bead on the inner z seam a lot.

    I looked in the Marlin settings on my Ender 5 and Vmax-e is 25. I wonder if faster retraction speeds were getting ignored.
     
  19. Aug 16, 2019 #49

    dr wogz

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    I am new to the PETG world, and am having eh same issues.. E-sun PETG 3 tries so far, and all have failed. stringy, globby,. and the feeder jams..

    The Maker gear post is a gerat one, and fond it yesterday. Despite many of the recommendations, I ended up with a print that crapped out with the first half hour, and a print that more than doubled in expected print time, due to s-l-o-w printing speeds..

    Will try again next week.
     
  20. Aug 16, 2019 #50

    manixFan

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    One thing that happened to me is the change in weather. By that I mean when I first started last winter I had good results with PETG. Then suddenly I started having issues, even with PLA. I finally figured it out when I was starting a print and the A/C kicked on. The printer is not in an enclosure and was right in the path of the A/C register. The cold air was creating a lot of issues during the print. I now close the vent and put a large piece of foam core in front of the printer to keep the air from hitting it. My prints are much better now.

    I also had to play around with the retraction settings quite a bit to avoid stringing on prints that have large gaps between areas, like a fin can. Also randomizing the seam on the external perimeter helped avoid a noticeable line in things line nosecones and couplers.

    Good luck,


    Tony
     
  21. Aug 17, 2019 #51

    Charles_McG

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    I finally got manageable prints and called it good. Retraction of 6mm at 25mm/s. A little coasting. And lowering the print bed compared to PLA. You don’t have to squish it onto the bed to make it stick (unlike PLA) - in fact, PETG hates it. If you’re getting build up on the nozzle, lower the bed/raise the live Z.

    I wrecked a spool of HB white PETG by attempting to dry it out in a food dehydrator. Probably unnecessary in the first place. My dehydrator runs too hot - the filament ended up wiggly from sags. Which increased the friction in the Bowden tube AND occasionally warped away from the extruded gear. So lots of under extruding. I fixed that by wedging a screw in the extruder spring and using a big rubber band to pull the arm down tighter. No grinding and much less under extrusion. I’m finishing that blasted roll tonight and will be moving on to the eSun.
     
  22. Aug 17, 2019 #52

    Ian A Dalton

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    Show us one of your results! I’m alway interested to see if workable means the same thing to others as it does myself. And yes, distance from the bed is critical.
     
  23. Aug 17, 2019 #53

    jbr

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    esun petg has been the only one to warp for me
    the red fin is esun and had 2 areas of separation, the rest are amazon basics
    had to use the soldering iron to fix the separations on the esun
    this was all printed using volcano with 65 watt heater and 1.2mm nozzle, 60C bed 280C nozzle

    [​IMG]
     
  24. Aug 17, 2019 #54

    Charles_McG

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    Let’s see.
    Here’s a 29-38mm adapter Indid as a test. I found a number of the stringing test objects to not be representative- time per layer too short, I think - so I did several of these as tests. This has some very fine threads but nearly no blobs.
    IMG_1022.jpg
    IMG_1025.jpg
     
  25. Aug 17, 2019 #55

    jbr

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    depending on the temp your casing gets to, you may find this adapter melted to your casing
     
  26. Aug 17, 2019 #56

    Charles_McG

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    29mm paper motor mount fits in as a liner.
     
  27. Aug 17, 2019 #57

    Ian A Dalton

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    Your level of acceptable print is about the same as mine. I just made a whole slew of eggtimer cases and got a ton of fine stringing.

    My bed seems to get hot enough and it’s 105 outside, I might try some ABS.
     
  28. Aug 17, 2019 #58

    jbr

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    that works, I did something similar
    [​IMG]
     
  29. Aug 17, 2019 #59

    dvdsnyd

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    I perused through this thread and didn't see anything about moisture and PETG.
    I fought and fought and fought with PETG for a while, and finally I tried drying it out. First I just used my oven set on the lowest setting as a proof of concept. It was a little too hot, but the results spoke for themselves. There are a couple options for drying out filament. I opted to modify an off the shelf dehumidifier, which I believe is really similar to the one the PrintDry guys based theirs on.
    Before I started to dry my PETG, it was super brittle, color was off, really stringy and just garbage, and super sensitive, almost uncontrollable with retract and other extruder settings.
    When dry, it is much easier to print, and much less sensitive.
    PETG seems to absorb water like crazy. I don't even bother trying to print PETG if it has been out in the open for more than a couple days. I throw it in my dryer first.
    Couple links down below of the dehumidifier and a link about PETG and moisture.
    Hopefully this helps!

    https://www.amazon.com/gp/product/B0188X0UT6/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
    https://www.matterhackers.com/news/filament-and-water

    Dave
     
  30. Aug 17, 2019 #60

    beeblebrox

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    I tried my first go with PETG from ZYLTech. I just got a sample to test. Got acceptable results at 228°c 90°bed temp and 60% fan speed. Retraction set 4mm @ 60mm/sec. Had some rough spots but PETG sands decently. Inside of cone and fin can were rough, but I have had difficulty with files generated with OPENScad scripts in general even with PLA. Making a tube in Tinkercad prints much better for example. This example print is BT-20 sized... IMG_20190810_104228456.jpg
     

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