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Has anyone had PLA distort during normal use? Trying to decide if a part made with PLA will distort if left in a car over the summer and I need to find another Filament to use. PLA is working, and cheap right now...

PLA will distort if left in the car with the windows rolled up or in the direct sun.

Pla will get soft at 55 - 60 deg C so parts for car use in the summer won't be a good if they made from pla.

ABS is the good choice as all the plastic in the car is made from abs like AC outlets.

Thanks!

How is PETG? Enough higher temp tolerance?

Yes it is but then you have different mechanical properties. If it will meet your design requirements it can handle the temperature.

The first mount I made to attach my dashcam to a suction cup was transparent PETG and it distorted to the point that it could reasonably be called melted while mounted on the windshield of the parked car one hot sunny day.

That is worse than "left in a car" since it was in fairly direct sun and under load at the time, but that was my experience, for what it's worth. I also figure the transparent material allowed some rays to penetrate into the body of the part, making things worse.

The opaque white ABS replacement has not suffered the same fate in similar conditions. I've also printed numerous ABS items for interior and exterior automotive use (a pedal extender, a shift knob, replacement trim pieces, and a mounting plate for a pickup truck cargo tiedown) with no adverse consequences to date (for exterior use, I apply a clearcoat for UV protection).