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The day I stopped using Bondo on ABS plastic bumpers
For like 3 years I was slapping filler on cracked ABS bumpers and wondering why half of them failed within 6 months. Then a customer brought in a bumper I'd fixed twice before and the crack had spread like a spiderweb under the paint. How long did it take you guys to figure out plastic welding?
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nancyjones8d ago
Why would I waste time learning plastic welding when a tube of this new 3M flexible bumper filler takes like 10 minutes and holds up just fine if you scuff it right? I've had zero callbacks in 2 years doing it the old way, so it sounds like a skill issue more than a material problem.
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nguyen.morgan8d ago
Yeah did you ever try sanding down to the bare plastic and hitting it with a heat gun first? That changed EVERYTHING for me. I used to just feather edge the crack and fill it too but the filler never bonded right because ABS flexes so much. Once I switched to plastic welding with a cheap harbor freight iron and some ABS welding rods the repairs actually held up. Now I only use filler for like tiny pinholes or surface smoothing after the weld. Still have to be careful not to overheat the plastic or it gets brittle and cracks again.
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