Fixing broken/missing screw bosses on plastic parts

pauly said

I've got some of the screws so I should able to figure out the length easy enough. I think I can glue them in and the run through the housing to keep them straight.

Grease should a great mold release- or car wax.

I'm a plastics engineer by trade- I can get lots of ABS runners from the parts we mold! I think the lenses are actually acrylic. If they were polycarbonate, they would have turned yellow from the sun over time

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Cool deal, as a plastics engineer you know what your doing.

I use an aerospace version of JB Weld. Its Araldite AVHV 1258 by Huntsman chemicals. It comes in a kit with 2 tubes the size of toothpaste tubes.

I have reinforced grilles from behind by using plastic pieces like splints, and gluing them in using solvent adhesive such as plastiweld. That works great too. If the cracks are not all the way across its also a good idea to stop drill the end of the crack with an 1/8" drill bit before repairing it. This helps keep it from continuing further.