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 5, 2019 #1

    Charles_McG

    Charles_McG

    Charles_McG

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    I’m having trouble getting control of PETG. I thought I had it dialed in, but curves ended up lumpy and stringy, while most flat sides do ok. Bed adhesion and layer-layer adhesion seem fine.

    Here’s my Quark holder. Brim detached. T did randomize the Z seam to hide it, but I didn’t see the print head crossing the print at the later changes.
    IMG_0861.jpg
    IMG_0862.jpg

    For comparison, here’s a part holder that three sides seem lovely.
    IMG_0863.jpg
    IMG_0864.jpg

    Printer is an Ender 5
    Manual level
    Fresh Hatchbox PETG
    235C , 240 first layer
    0.2 thickness, 0.4 nozzle
    55mm/s speed, half for bottoms, top, outer
    0 fan on the Quark holder. 25% half way up the tool holder - didn’t seem to make a difference.

    Thoughts/tips? I like the way PETG feels. I’m annoyed by the lumps and strings.
     
  2. Mar 5, 2019 #2

    cwbullet

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    How many items on the sled at one time?

    I usually lower my temp to 230 for Hatchbox.
     
  3. Mar 5, 2019 #3

    Charles_McG

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    One item printing at a time.

    And I might be at 230, 235 for the first layer. I’ll have to check Cura.
     
  4. Mar 5, 2019 #4

    mpitfield

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    I thought the spider webbing or whisps were sign of too high temps and not enough retraction. Having said that I use Slic3r or Simplify3D and have my temps set to 250 first layer and 240 for the rest and no fan for the first three layers then 30-50% from there up. I also have slower speeds, 40mm/s for top, 25mm/s external perimeters, the 80mm/s for infill.

    I have Cura installed and have printed PETG successfully but I can't recall how well and what I printed to compare, also I have never used Hatchbox.
     
  5. Mar 5, 2019 #5

    manixFan

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    I had to increase the retract amount to eliminate blobs on layer changes, and found that choosing random layer start helped. Blobs and stringing can also also be caused by over-extrusion, you should be able to adjust that in your slicer. Here's a good overview on it:

    https://help.prusa3d.com/article/d9j1xdg7vj-extrusion-multiplier-calibration

    You also generally need to raise your first level Z calibration a bit to get a better first layer. That may help your brim issue. I had a lot of trouble when I moved my printer near a window when it was cold, there must have been enough of a draft that it really messed with the prints. So check the printer environment for drafts or maybe a register blowing on it.

    I am using a box of Hatchbox PETG and I really like it. It's worth the effort to get it dialed in.


    Tony
     
  6. Mar 5, 2019 #6

    DRAGON64

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    When I first started with PETG, Cura had the retraction distance set at .5mm. I upped that to 5mm for Hatchbox, and 8mm for Amazon Basics. This helped to get rid of the serious stringing and globbing issues.
     
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  7. Mar 5, 2019 #7

    Locksmith

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    Like others have posted check your retractions, I have mine set to 2mm on my mk3. Temps 230-235 and 75-90 on bed. There are several small test you can run on thingiverse just search for retraction test or stringing test. Then you can print a lattice to test your settings. "see video"

     
  8. Mar 5, 2019 #8

    Charles_McG

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    Many thanks folks. So lets review my checklist.

    I checked Cura, and I am set for 235C/240C 1st layer, so I can back that off.

    I'm still playing with what minimum fan setting actually turns the fan on. 25% wont get it turning, but if you give it a flick, it stays spinning. I didn't see a difference in the part I was printing at the time. I've had really nice faces print with fan set to 0%, so I'll keep trying that for a bit more.

    I think I've got my bed set pretty well Z-wise. The Ender 5 lowers the bed instead of raising the nozzle, so my sense of Z+ is probably upside down. I found that the PETG did better with the nozzle slightly higher above the bed than for the PLA I was using (Shaxon). Specifically, I level with slightly less friction between nozzle and paper for PETG than for PLA. I'm using - and LIKE - the flexible magnetic print surface, which does limit my bed temp. But it's laying down and sticking at 70C. Tighter than PLA at 60C. In the picture in the first post, I had removed the brim just before the photo.

    Extruder calibration. Had been on my original checklist - but the PLA was doing so nicely I dropped it. I can revisit. Over extruding makes some sense, 1-2cm of extrusion oozes out post-print.

    Retraction distance. Default is set to 5mm for Cura 3.6/generic PETG profile -BUT- retract at layer change is turned off. I can fix that.

    String test prints - thanks for the search terms. Added to my collection.

    Edit to add:

    How about Z Hop during retraction? Helpful? Distance?

    I have a pet peeve with Cura. I use a Surface Pro 5 for most of my work and play. Cura doesn't recognize the pen. At all. Luckily, I keep a mouse in my laptop bag - but I'm not used to using it.

    Charles
     
    Last edited: Mar 5, 2019
  9. Mar 5, 2019 #9

    cwbullet

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    I had an issue with PETG sticking to my nozzle. I started using cleaning my bed with Dawn every 2 days and using Aqua Net hair spray to promote adhesion.
     
  10. Mar 5, 2019 #10

    Charles_McG

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    Ok - so if it’s sticking to the nozzle, why do you treat the bed instead of treating the nozzle?
     
  11. Mar 5, 2019 #11

    cwbullet

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    If you make the bed more sticky, it is less likely to stick to the nozzle. I read this on the printer manufacturer’s website.
     
  12. Mar 5, 2019 #12

    Locksmith

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    you use glue stick and hair spray as a release agent, not for adhesion. PETG sticks almost to good onto pei. If you are getting lifts or not sticking you may need to treat your pei. Depending on the type of pei you can use Acetone "every so often", or isopropyl 91-99% "do not use nail polish or anything else you think or says is iso. Its cheap buy it pure. In extreme cases you can use 1500-2000 sand paper to scrub away the oils that you cant get.

    My routine is wipe with iso 99% before every print
    Once a month clean with hot water and dawn pure soap "dawn pure, no smells, same with paper towels your trying to rid the surface of all oils.
    Acetone only if the above doesnt work. Acetone will dissolve the pei - Ruined my first pei sheet this way :(
    Ive only done the sandpaper to one printer that is extreme cases only right before buying new bed.

    Even your finger touching the bed will create a barrier between the plastic on the pei be very carefull.

    I have replaced or repaired probably 1/2 a dozen beds at maker space because the petg will lift the pei off when you are removing the part. That is why they recommend you remove parts at 50-60c bed temp to help this.
     
  13. Mar 5, 2019 #13

    cwbullet

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    Not entirely true. Hair spray and to less degree glue stick work as a release agent when the bed cools. They promotes adhesion when it is hot.
     
  14. Mar 5, 2019 #14

    mpitfield

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    I have my temps and PLA / PETG filaments dialed in on both my PEI and textured sheets that I rarely use glue. It is kind of strange but when the bed cools down the prints aren't even sticking to the bed. But if the bed is hot then they are stuck on well.
     
  15. Mar 5, 2019 #15

    Charles_McG

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    As I mentioned above, I'm using the flexible magnetic surface Creality sells on the Ender Pro 3 and Ender 5. I don't think I'm having adhesion problems with the PETG. As noted, it almost sticks too well. And removing at ~50C does help. Periodic isopropyl cleaning and refresh with Aquanet (I think a PVA derivative is the important part) helped with PLA. Though getting the bed Z correct helped more.
     
  16. Mar 5, 2019 #16

    Locksmith

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    It weird you would think pei is pei but for my prusa stock sheet I use glue stick so I dont tear it, thekkiinngg sheet I dont do anything with just iso 99% before every print, Lulzbots pei you must use either glue stick or hair spray or it will destroy it seen that a few times. Rostock delta printer is glass there you have to use something like glue stick or hairspray other wise you have to print with crazy high bed temp. There is a mk2s clone here that petg wont stick to no matter what we try. Thats problem with 3d printing in general no one fit all solution. I just wish we didnt have 10+ styles of printers here makes solving problems that much worse.
     
  17. Mar 6, 2019 #17

    Charles_McG

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    Ok, I dropped to 230C (235C first layer), adjusted the extruder steps (it was 94.6mm for 100mm commanded) and adjusted the flow to 92% (.87mm for 2x0.4mm layers). The repeat test square was within a couple thousandths. And only 1 hair.

    Trying the lattice cube now.
     
  18. Mar 6, 2019 #18

    cwbullet

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    I am printing a rocket fin can for BT80 and have quite a few hairs. They are sandable. I will live with it.
     
  19. Mar 6, 2019 #19

    manixFan

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    You can also hit the hairs with a heat gun but very carefully. For some shapes it is easier than sanding. Practice on some cast-off parts first. I had a couple of fin cans with a lot of stringing and over-did it on the first one (warped a fin just a bit) but the second one cleaned up pretty well with no damage. I now know what setting on my gun to use and to slowly move closer while always keeping the heat gun moving.


    Tony
     
  20. Mar 6, 2019 #20

    Charles_McG

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    Okay, the cube printed fairly well, I think. I’m seeing spiderwebby hairs, rather than thick strings. I can see how a heat gun would settle these little threads right down. The undersides are a little rough, and seem to be the source of most of the hairs.

    5mm retraction, at layer change, 1mm Z hop. No fan.
     
  21. Mar 6, 2019 #21

    Charles_McG

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  22. Mar 6, 2019 #22

    cwbullet

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    I am printing a second fin can - this one has much better results. If so, I will share the settings tonight. I used the settings of a couple this posted in this thread.
     
  23. Mar 6, 2019 #23

    Locksmith

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    I don't use Cura but here is the raw data of my slicr settings if you want to pick threw it, I have very high luck with petg. Do not copy paste the settings as I also have a MMU2 and there are setting for that in here. But might be useful to ya to compare
     

    Attached Files:

  24. Mar 7, 2019 #24

    cwbullet

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    I went with the stock SLIC3R PETG settings with:
    5mm retraction
    Temps: 240 for the first and 230 thereafter
    slower speeds, 40mm/s for top, 25mm/s external perimeters, the 80mm/s for infill

    This is near perfect for me with Hatchboc PETG. Minimal stringing (2-3)
     
  25. Mar 7, 2019 #25

    Charles_McG

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    Went back to my Quark holder. Outside is better, but the inside is still a stringy mess.

    In the picture, temp increases from left to right - 220, 230, 240.
    At 240, I bumped up from 40mm/s to 50 and increased retraction from 5 to 7. I also fixed the Z seam. It turned out brittle, and you can see under extrusion (I think) on one side of the seam. Nearly all the strings originate from one the Quark guides.

    Hmmm....
    IMG_0870.jpg
     
  26. Mar 7, 2019 #26

    cwbullet

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    If you send me the story files or a link in a PM or a conversation if they are on thingverse and I will look at them. I will try to print them and let you know what I get.
     
  27. Mar 7, 2019 #27

    Charles_McG

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    I haven't put it on Thingiverse, but I don't consider it proprietary. Attached. It's meant for midpower - put into a 24mm motor mount in the nosecone, using the Estes retainers to hold in.

    I'm starting to think that I just accidentally made a hard to print design. It works great in PLA. I like the higher flexibility and lower brittleness of the PETG.
     

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  28. Mar 7, 2019 #28

    cwbullet

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    Will test it tonight when I get home.
     
  29. Mar 7, 2019 #29

    Locksmith

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    Not sure if Cura has this but on a couple printers we use a option called "avoid crossing perimeters" which if the head needs to go to other side it wont go straight there it will instead move around the top of current layer to get there. Might be an option to look at.

    And there is nothing wrong with the design for 3d printing.
     
  30. Mar 7, 2019 #30

    Charles_McG

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    I think that might be 'Combing' in Cura. If I understand it correctly.

    It should be a dead easy print. And is in PLA. It's the PETG that's giving me fidgets.
     

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