Frame parts cracking

This topic contains 7 replies, has 6 voices, and was last updated by  Vincent Pollaro 5 months ago.

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  • #35617

    Cliff
    Participant

    I’ve printed all of the New parts about 3 months ago. I assembled the frame and never got around to wiring so the frame has just been sitting. I find time to set it up and find stress cracks in most of the parts. 3 different brands of PLA. Has anyone had an issue with this and/or have a suggestion? I really don’t want to print them again just to have them crack again. I do live in southern Arizona where it is really dry. I’ve attached files.
    Any help is appreciated. I’ve thought of trying printing the parts in PETG.

    #35659

    Wow, that’s bad luck…
    Never had such an issue, I think it might very well be weather related. Guess PLA doesn’t suits all parts of the world, I never had that kind of problems here.
    I think you have no choice but to switch to another material, ABS, nylon or PETG, just choose the most rigid you can

    1 user thanked author for this post.
    #35675

    Tormans Elefernus
    Participant

    A very interesting problem … Unusual is that structural cracks pass through the filament layers as if they were tensile stresses. Can not it be a problem in too much tightening screw connections? An alternative solution to the problem would probably be to use a more supple material, just beware of a larger shrinkage of ABS – I have proven to print these parts with a scale coefficient 1.063
    Please excuse my English terminology – Engineering is not the focus of my profession, I miss professional vocabulary

    2 users thanked author for this post.
    #35690

    John
    Participant

    I’ve had it happen to a few, but in my case it’s been overtightening that caused it. I’m in Idaho where it’s really dry for part of the year and pretty cold for part..

    1 user thanked author for this post.
    #35695

    Ryan
    Keymaster

    All of them look like overtightening except the roller mount, still could be over tight but it is not cracking from the screw hole and it is flat on flat. I can’t imagine how such large cracks happen on that plane of a 3d printed part. Once the part is printed I can’t imagine anything other than direct sun effecting it so much. It can handle hot cold and humid pretty well as far as I know. My friend had a 3D printed part (pretty sure it was PLA) glued on the outside of his car in San Diego, it was still there when I left. It made it through the heat and the rain.

    1 user thanked author for this post.
    #35767

    Cliff
    Participant

    Should all of the big bolts go into the holes smooth or should it feel like its threading itself into the plastic. All of my parts felt really tight during assembly. Maybe my printer isn’t printing to scale and all my parts are just a little too small. I might try to print one or two small pieces at like .5 or 1% bigger and see how the bolts fit. Thanks for the comments and info.

    #35873
    Should all of the big bolts go into the holes smooth or should it feel like its threading itself into the plastic. All of my parts felt really tight during assembly. Maybe my printer isn’t printing to scale and all my parts are just a little too small. I might try to print one or two small pieces at like .5 or 1% bigger and see how the bolts fit. Thanks for the comments and info.

    Yeah, they feel like they thread themselves. At least on mine.

    1 user thanked author for this post.
    #36399

    Vincent Pollaro
    Participant

    You could try drilling them out slightly (if you re-print) to avoid any extra stress internally on the holes that might lead to failure. I am also in Arizona (Phoenix – 118f outside currently) and normally the ambient temps in my shop (not cooled when I’m not in it) and ultra low humidity do not adversely affect my printed parts.

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