Andrew Zonenberg

Another day, another of the little one's things repaired with a hot air tool and a bit of poking.

So many people assume broken plastic is unrepairable garbage because it's hard to glue.

But if it's a thermoplastic, as almost all mass market plastic goods are, all you need to do is gently heat up the pieces until they soften and push them back together to form a solid weld. Filler rod can help in some cases but isn't always necessary or useful depending on the nature of the repair, for flat surfaces I've had decent results just using a screwdriver to lightly press the heat affected zones into each other until they merge.

8:47pmWeb
Show threadChris Petrilli14h ago
@azonenberg I feel like I use my hot air gun for 5x as many other things as I do reflow work.
Show threadAndrew Zonenberg14h ago
@petrillic I have a separate one for random repair jobs so the soldering one can stay on the bench, it's a pain to move it around because of how it's wired
Show threadrobryk14h ago
@azonenberg How can you tell if it's a thermoplastic? By trying?
Show threadAndrew Zonenberg14h ago

@robryk you can look at the recycling symbol. Polyethylene (HDPE and LDPE), PVC, and polypropylene, among many other common plastics, are.

Anything injection molded is made from a thermoplastic by necessity since the molding process requires heating and softening the raw material to squish it into the mold.

Epoxy resin, as used in fiberglass parts, is one of the few common plastics that is *not* a thermoplastic.

Or yes, gentle heating. If it softens it's a thermoplastic, if it shows no change in hardness until reaching the point of discoloring (beginning to char/decompose) it's a thermoset and can't be heat welded.

Show threadDrahflow14h ago
@azonenberg This works also (with more precision but less weld depth) with a soldering iron set sufficiently low.
Show threadAndrew Zonenberg14h ago

@drahflow yeah but no way am i getting random plastic all over my nice Hakko tips.

I much prefer the hot air "torch" technique. If you use filler rod it's pretty similar to oxyacetylene brazing except the rod doesn't fully liquefy and there's no capillary action, it just sticks in place where you placed it

Show threadDrahflow14h ago
@azonenberg At least LDPE, PLA and ABS seem to leave my tip nicer than before. Then again, I don't solder much and it might well be my inability talking. ^^