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Solved Help - Can't figure out PETG

Discussion in 'Troubleshooting' started by Ryan Whitney, Dec 20, 2016.

  1. Ryan Whitney

    Ryan Whitney New Member

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    I've tried both the black and translucent filament from Hatchbox, varied bed temps from 75 to 90deg C in 5 deg increments, varied the extrusion temp from 235 to 255deg C (black filament lists temp of 240-260C), and tried every combination in between. Not sure what's going on but the first layer or 2 seems to work fine and then the infill gets extremely rough like the layers or pulling away from the bed and the feed is scraping across the surface. I've seen a lot of posts about how great the material is compared with ABS, but can't figure it out...can someone send me their full list of settings? I'm thinking it has to be something else in my layer height, z-offset...etc.

    Robo R1 Plus

    Thanks!
    Ryan
     
    #1 Ryan Whitney, Dec 20, 2016
    Last edited: Dec 20, 2016
  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Even given your current issues, just remember this one thing, ABS sucks on FDM printers!

    Z-Offset is only used in the first layer, so if your bed adhesion is good then it is not that.
    A picture is worth every single word you wrote in your post and much more.
    Since all machines are different and people have different ideas of how to make things work (you know, more than one way to skin cats) just posting settings without knowing how they work in unison will not really be of much benefit. better to include a picture and we can go through suggestions based on what we see.
    I too have found that Solid Color PETG requires higher temps to extrude smoothly than translucent ones
     
  3. Toro1966

    Toro1966 Active Member

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    What are you printing? Also, your speed may be the problem. Good example - I printed a single ornament at 60mm/s using PETG and it came out beautiful and smooth. I decided to try and print 9 of them at the same time. They fit fine, but had the same reaction as yours. First inch or so printed great but the rest of it was very rough. I am printing at 240/70 and with the exception I listed, everything prints beautifully. Also remember with PETG, that it DOES NOT like to be pushed down like other filaments. Meaning, you don't want to press it flat with z offset like you do PLA or ABS. if you do, it will end up globbing up on your hotend and then coming off on your print at best, and at worst, knocking your print or supports over.
     
  4. Ryan Whitney

    Ryan Whitney New Member

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    Thanks Waldo. Was going to upload a pic last night but black filament on the black bed was hard to make out. Currently trying the black Hatchbox PETG filament, actually got good results last night except for 2 spots in the print where something is going haywire with the material. Started at 245/80, and then changed to 240/85 with 25% fan at layer 4 when I noticed the problem. I had to pause the print and cutaway the material at the defects with dikes because the were protruding in the z direction. Layer height is set to .1 and think the speed was at 80mm/sec so I'll try to reduce the speed per Toro's comment
     

    Attached Files:

  5. Toro1966

    Toro1966 Active Member

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    Looks like z is set too low. Raise it. For PETG, you almost want a bead, not a flattened extrusion. See the areas of what look like texture and not smooth in your bottom layer. Nozzle is too low.


    Sent from my iPhone using Tapatalk
     
  6. BillUpNorth

    BillUpNorth New Member

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    With Hatchbox Blue PLA on my stock R1+, I've had good success with the following (using Simplify3d):

    - Auto extrusion width
    - Retraction: 1.7mm, lift .4, 30mm/s retract speed, Coast .3mm, Wipe 5mm
    - .25mm layer height, 3 solid top, 2 solid bottom, 1-2 shells, 90% first layer height, 40% first layer speed
    - 3 skirt outlines
    - Extruder 247, Bed 80C at layer 1, PVA glue wash for adhesion (aka to prevent more bed chips)
    - 3200mm/min, Outline underspeed 50%
    - Fan 0 for first 2 layers, 100 at layer 3 and above
    - Touching the bed at the front left corner to clear off junk before bed probe

    Still tweaking to go, but most things I print with those settings have minimal artifacts, good layer adhesion, etc.
     
  7. Toro1966

    Toro1966 Active Member

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    Here's a litho I just printed last night with Inland PETG. [​IMG]


    Sent from my iPhone using Tapatalk
     
  8. Ryan Whitney

    Ryan Whitney New Member

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    Damn you Toro! Tried it again and watch for the 1st 15 min. First layer looks great with good adhesion, but when the extruder moves to start layer 2 it's dragging through the PETG it just laid down slightly and then all the melted plastic on the tip is demolishing the first layer...any thoughts, never seen it do that before? Maybe because I increased the Z offset for layer 1 it's not picking up as much as it should between layers 1 and 2?
     
  9. Ryan Whitney

    Ryan Whitney New Member

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    This is the melted Petg on the tip after it drags
     

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  10. Toro1966

    Toro1966 Active Member

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    Sorry Ryan. We'll get it figured out!What is your Z-lift? Also - what are your retraction settings? Are you using MatterControl?
     
  11. Ryan Whitney

    Ryan Whitney New Member

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    This is the beginning of layer 2 right after it dragged the dirty tip perpendicular across the initial layers
     

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  12. Ryan Whitney

    Ryan Whitney New Member

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    Yep, using Matter Control.
    Z lift = .5mm
    Retraction length on move = 1mm
    Wipe after retract not set
    1st layer height =.3mm
    Nominal layer height = .15
    Those are all default, never played with them

    Thanks for all the help, hope to have prints like yours when I grow up!
     
  13. Toro1966

    Toro1966 Active Member

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    You might want to try a little more retraction. PETG tends to ooze. That said, those settings don't look bad. If you want to try something, send me your file, I'll slice it and you can print the GCode. Might help to rule out the slicer settings. What do you have your z-offset set to?
     
  14. Ryan Whitney

    Ryan Whitney New Member

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    Thanks Bill, updating my settings to match!
     
  15. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    From your last picture there is not enough bed adhesion. So either your printer setup has a layer height that is too high. You really shouldn't print anything over .3 mm with a .4 mm nozzle orifice. If it is not that, then your Z-Offset is too high, Your first layer shouldn't look like a bunch of strings side by side, it should look pretty solid. As a result of such poor bed adhesion PETG which loves to stick to nothing other than itself, you are getting it pulling up. You need to start from a better mechanical position rather than trying to fix it all in your slicer.
     
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  16. Toro1966

    Toro1966 Active Member

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    Agree with Waldo. Looks like you need to lower a bit. That said, it's a delicate dance with PETG, because too close will booger up and scrape off on your print while it's in progress.
     
  17. Ryan Whitney

    Ryan Whitney New Member

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    Alright guys thanks for all of the help. Took a hiatus for Christmas, but after a few more trials last night everything is dialed in perfectly and got the best print I've ever seen on the Robo.

    • Switch from printing on the bare glass with glue stick to putting down a sheet of PET + glue stick for better adhesion
    • Dialed the Z-offset back in, thanks for the advice Waldo and Toro
    • Found Waldo's remarks on another PETG thread and followed the comment to increase speed and reduce the extrusion multiplier. Was running at 40mm/s & 100% and changing that to 55mm/s & 98% made all of the difference in the world.
    • Z-lift for retractions is now .9mm
    • Followed Bill's .25mm layer height, 247 extruder temp, fan off for 1st 2 layers and then 100% for all others
    • Only other change was running at bed temp of 85C, found that worked a little better than 80C
    Great teamwork (by you guys, not me), it was a big print and looks great. Can't wait to use PETG again
    Printed Bottle Holder.JPG
     

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