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  1. #1

    petg print very brittle

    I bought some black esun petg the filament seems fine on the spool not brittle but all the prints are very brittle. Printing with a qidi x-one with temps at 240 head and 70 bed. Esun recommends 230 - 250 head no heat to 80 on the bed. I'm at my whits end trying to figure this out i'm thinking bad filament. What would cause this and could it be bad filament?

  2. #2
    Are layers separating or is the print shredding to pieces after removal?

  3. #3
    No layers look fine if i print something flat lets say and try to bend it it snaps with almost no flexing. I think i may have solved it i turned the bed heat down to 40 and head down to 235. I tried a couple of small prints and the brim and prints weren't brittle. Printing a big print now will keep you informed. Thanks.

  4. #4
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    Hydrolysis of PETG causes brittleness as the polymer breaks down when processed with significant moisture content.

    As does excess heat.

    Since most people don't have a major problem printing filament that's wet by my standards (and the manufacturer's) I would wager that the heat decrease will improve things on your larger prints.

    Also be aware that thermal degradation is a function of time as well. If your layers don't have enough time to cool, heat can possibly build up to just below melt temp which can cause it too, but you would have to have some very very hot layers to do that.

    With that said, please do report back with results. Too often people search and find a thread with their issue but it's never resolved as the OP comes back and says "got it, thanks" and never says what or why.

  5. #5
    Super Moderator curious aardvark's Avatar
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    Ah - cheers for that.
    I've been printing pet-g at 245, certainly not brittle, so lower printing temp is better for pet-g.
    worth knowing :-)

    And yeah, if we deleted all the one time posters we'd lose at least half the threads in the forum.

  6. #6
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    Quote Originally Posted by curious aardvark View Post
    Ah - cheers for that.
    I've been printing pet-g at 245, certainly not brittle, so lower printing temp is better for pet-g.
    worth knowing :-)

    And yeah, if we deleted all the one time posters we'd lose at least half the threads in the forum.
    As with all things, every adjustment must be made "consistent to quality", so every rule has it's asterisk.

    Sadly the 3d printing industry has absolutely zero standard when it comes to filaments, base resins, additives, processing requirements, etc.

  7. #7
    Super Moderator curious aardvark's Avatar
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    but on the whole I'm better printing pet-g cooler rather than hotter ?

  8. #8
    Ok it turned out to be wet filament. Put it in a 90 deg f heater overnight and prints are much better. Printing at 245 and 60 looks pretty good. Just some fine tuning and I should be in good shape. Thanks for all the help.

  9. #9
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    Quote Originally Posted by curious aardvark View Post
    but on the whole I'm better printing pet-g cooler rather than hotter ?
    Which would be right in line with what was stated, that hotter temps risk degradation of the material.

    When processing plastics the lowest temperature you can manage to get working is always preferable.

    Quote Originally Posted by butchs38 View Post
    Ok it turned out to be wet filament. Put it in a 90 deg f heater overnight and prints are much better. Printing at 245 and 60 looks pretty good. Just some fine tuning and I should be in good shape. Thanks for all the help.
    Score one for science!

    That said, you will see additional improvements if you dry the parts to a much lower moisture content than is possible with hot air alone, however if you are at an acceptable point then I see no reason to investigate further.

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