OT, car repair: Do those cheap plastic welders really work?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41592

I got one of this from HF but non of the plastic rods stick to anything. I
was hoping to fix my bumper and some plastic parts. Ended up using epoxy on
one side plus a thin layer of fiber reinforced Bondo on the other side and
that may not work too well either. Has any of you make this type of welding
unit work. I'm playing around with it, perhaps its my technique. Not new to
steel welding, just not plastic.Oh well.

The ones I saw that work are some industrial units that are price way out of
my range for just an occasional repair.

 

I think you overpaid for what you got. This would have worked as
well or better: http://www.hardwarestore.com/media/product/101061_front500.jpg

 

How does that thing work? Does it burn acetylene?

 

No, its an electric heat gun with the filtered air controlled by the
pressure regulator. So you need an air compressor with an air filter and
120V outlet.

Works like TIC welding: You hold the furnished plastic rod (3 types of rods
furnished with kid) that matches with the bumper material and the tip blows
hot air on the rod and damaged area together so the parts bond together. A
good plastic bond would be stronger than the mother material - just like
good welding and solid wood glued joints.

High learning curve to make it work, just like TIC welding. Playing around
with it now.

 

LOL, this has no structural value - duct tape would been better than this
for the bumper! I've repaired mufflers and tailpipes with a wire feed welder
but many times as the corrosion is so bad, its just better replace the
suckers. BTW, for tailpipes and mufflers, foil works pretty well, the one
with sticky back for HVAC. YMMV.

 

The problem you will have is mating the plastic components. The two
materials have to both melt at about the same temperature and the
materials themselves have to be compatible, i.e. they will fuse
together. I suspect that some plastics may not combine well if at all.

 

Yike. I've just spent a weekend trying to fix some kind of big plastic
storage bin (ok, i have too much time on my hands) which involves
figuring out what kind of more or less clear plastic it is, and/or
what the melting temp is; neither of which I could do. (my cute little
$10 IR thermometer was doing OK on the melting point test until it
started to register "HIGH" just above 250 fahrenheit or so, when the
plastic was still looking good).