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plastic welding

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Devlin

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Dec 31, 2002, 4:15:36 PM12/31/02
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I want (need) to get a plastic welder and do some extensive repairs.
The repairs are to ABS street fairings and range from minor cracks to
big ugly busted up cracks. Any advice about getting into platic
welding? Does anybody know which techniques provide the best welds?
Airless or hot air? Any brand names of welder manufacturers that I
should look for or lookout for?

TIA

Ray Curry

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Jan 1, 2003, 3:01:17 PM1/1/03
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In article <932c74e4.02123...@posting.google.com>,
rockstarwal...@hotmail.com (Devlin) wrote:

Try the following: http://www.urethanesupply.com/index.html

--
Advice is free... and worth every penny.

Chris H

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Jan 4, 2003, 4:34:55 PM1/4/03
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I have welded plastic in the past. It was something I did at wor to keep
from being bored. To weld plastic is just like welding steel keep the heated
air in front of the welding rod . On a second note: Remeber to keep the air
flowing through the torch or you'll have a very messy meltdown.

Chris


ES

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Jan 10, 2003, 1:47:57 PM1/10/03
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rockstarwal...@hotmail.com (Devlin) wrote in
news:932c74e4.02123...@posting.google.com:

I repaired several ABS fairings by plastic welding, in one case I made
one complete fairing out of two busted ones damaged on opposite sides,
welding the good halves together.

When first tried plastic welding, I borrowed an expensive hot air welder,
which is basically a heat gun with more of controls for temperature and
air speed. Then I noticed a kit (also expensive) that used an airless
welder, which resembled an old fashioned pencil type soldering iron. The
lights went on, and off I went to home depot, bought a pencil soldering
iron for 10 bux. Guess what, it worked like a damn, better than the hot
air unit.

What you need to do is vee groove your joints, this can be done with a
hobby knife or a dremel (dremel is best). You will also need filler rod.
Most MC fairings are ABS. ABS is usually black when you sand off the
paint. If the plastic is not black it may not be ABS, and you will have
to find out what it is. If you can't identify the plastic you can make
your own filler rod from scrap plastic taken from the identical part, cut
strips that are as wide as the thickness of the plastic, (usually about
1/8"). Do all your welding from the back (if you can). Use the
soldering iron to melt the vee-ed out joint and filler rod together,
pushing the welding rod into the joint. Use the soldering iron to soften
the plastic each side of the the bead for 1/2" so each side is buttery
soft on the surface you are welding.

As you are welding, melt a 1" wide strip of stainless steel window
screening into the bead. Push the screen into the melted plastic, and
use the soldering iron bury the screen and spread melted plastic over the
it. Squishing down will push plastic through the screen holes, this is
the plastic you will use to cover the screen. Check other side for
penetration, a good weld should be obvious from the opposite side. Too
much penetration may cause problems on the good side, so be careful. Let
the joint cool, then you can sand, fill, prime and paint using auto body
wet and dry paper, bondo and automotive primer.

Voila brand new fairing.

Practice on scrap.

A lifetime supply of ABS plastic welding rod can be had for a few dollars
from a plastic supplier or an autobody supplier. If you don't believe a
10 dollar pencil soldering iron can possibly work, an autobody supply
shop will sell you their version for about 200 bux. Either will work
better than a air type welder, which will cost you at least twice as
much. Some air welders need a separate air source, which means more bux
for a suitable compressor if you don't have one already.

I initally thought the soldering iron would not work, because I figured
the plastic would stick to it and make a big mess. Well the plastic
doesn't stick so long as the soldering iron is at its operating
temperure. Plastic will stick to an iron that is not hot enough. If all
you have is a gun type soldering iron, it will work too, but not as well,
as you do not have enough tip. The pencil type tip to use (they are
replaceable) is the chisel or diamond point type about 1/4" or 3/8"
diameter.

Soldering iron heat is about right for ABS plastic welding. Heat your
plastic until it is soft and pliable, you are not trying to liquify it,
just make it kinda soft so you can mold it like the plasticine or clay.
Plastic will stay soft and hot for quite some time after heating. Be
careful re fumes, there should be no burning or more than a touch of
smoke when you are welding, smoking means too much heat, pull the
soldering iron out, and work the plastic with the welding rod or a flat
tool like a teaspoon. Fumes will kill you and it won't take long, weld
in a well ventilated area! Blistered welds indicate too much heat.

THere may be a light thin coating of plastic on the soldering iron tip
after you are done. Clean the iron by leaving the iron on for a few
minutes in a well ventilated area (don't breathe the fumes), the plastic
will burn off. After the iron cools the charred plastic can be wiped
off.

Devlin

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Jan 16, 2003, 10:54:52 AM1/16/03
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thanks! I'll give the soldering iron a try seeing as i already have
one. i'll post a follow up.
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