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Old 04-17-2008, 06:46 AM
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obseq obseq is offline
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Question Welding and fabricating thermoplastics

Does anyone have experience in welding and/or fabricating thermoplastics?

I am looking to experiment with a few possibilities, (extremely thin layers, in sheet form):

-Perforated Polyethylene
-Perforated Polycarbonate
-Perforated Polypropylene
-Nylons, et cetera

While all of the above thermoplastics are available in solid sheet form, I suspect that the perforated sheets will better lend to layering and subsequent sanding down down to an even, matte surface.

If anyone has insight into appropriate tools and methods, I would appreciate it!

Last edited by obseq : 04-17-2008 at 09:11 AM.
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Old 04-17-2008, 11:12 AM
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Ries Ries is offline
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Re: Welding and fabricating thermoplastics

I have done a bit of this.
Its stinky, toxic, and easy to make mistakes.

Best done with electric or hot air heat sources, not flame.

They make hot air welding guns for plastic, which while not cheap, are probably worth it, as there isnt really an easy substitute.
You can cut strips of filler rod from your same plastic.

You need to be able to finely focus very hot air.
Theoretically, you might be able to make a tip for a heat gun, but a decent heat gun costs a hundred bucks or more, and by the time you make a tip, you are getting close to a real welder.

The other thing I have done a lot is using resistance heaters to heat a line in plastic, then bend it hot.
These heaters are cheap, and 110volt.

Plastics are not very esthetically pleasing to work with- they are, after all, pretty much pure petroleum.
Which is one reason I liked working with them a bunch in the 70's- they were so anti-hippie, they offended nicely.
But ultimately, not satisfying.

Use a respirator, and good ventilation- they do nasty things to your innards.

Being oil based, the prices have gone up a bunch lately for new. Course, milk jugs are a good source of free material.
Been There.
Got in Trouble for that.
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Old 04-17-2008, 03:43 PM
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underfoot underfoot is offline
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Re: Welding and fabricating thermoplastics

In my experience, nylon, polycarb and polyethylene, would be the more difficult plastics to weld
being thermo plastics doesn't mean they will easily weld,

as Ries suggested a plastic welding gun because of the fine temp control,
and also using offcuts of the materials you're welding will ensure compatability,

polypropylene, pvc, and acrylics would be the easier welds
PVC would be the most versatile IMO
again, as Ries suggested, the stuff is dodgy, wear all the gear,

also, some of the new generation hot glues may be worth experimenting with.
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Old 04-17-2008, 04:45 PM
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WeiMingKai WeiMingKai is offline
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Re: Welding and fabricating thermoplastics

Harbor Freight sells a plastic welder with the compressor built in for ~70$. If you have your own air supply then they sell one for ~30$. I haven't used any of these products so I can't say what the results are.

Miwa Koizumi had a post over at the makezine blog about her jellyfish sculpts from soda bottles. IMO her squiggly sea critters are quite attractive to look at and her technique of heat gun & soldering iron is beautifully direct and simple.
Brian Jungen did an interesting whale-like skeleton out of plastic chairs.

The Makezine site has a TON of stuff about how to take plastic shopping bags and turn them into a large array of things - the process usually starts by getting a bunch of bags and fusing them together into thicker plastic sheets with a clothes iron or 'quilting' them with a soldering iron. Of course it would be simpler to spend a few bucks and buy plastic of the variety, thickness, and color you want from a supplier and proceed from there.

I purchased a heat gun (a hair dryer with a bad attitude) not too long ago but haven't had time to take it out of the box and try it out on things like cut up water/soda bottles & that 'clamshell' packaging plastic everything comes in nowadays. If anyone has experience fusing plastic scraps into sheets/shapes I'd love to hear your ideas about the best surface to work on/over that would prevent hot plastic from sticking to it and the best types of plastic packaging 'garbage' that can be recycled into a useful art material.

Plastic is all around us it seems, I sometimes think the world will eventually be covered by a layer of used water bottles & shopping bags. If all it takes is a little well placed heat to turn this garbage into a useful sculptural material - maybe more of us should look into it.

Good Luck.
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Old 04-17-2008, 10:33 PM
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ahirschman ahirschman is offline
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Re: Welding and fabricating thermoplastics

What are you building? Does it have to be thermoplastic or can you go with a castable plastic?

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Old 04-19-2008, 06:44 PM
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obseq obseq is offline
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Re: Welding and fabricating thermoplastics


Thanks for the straight facts on the volatility of working with these.
I wasn't exactly sure about the trade-off in toxicity between thermoformed versus castable plastics. I've got a decent heat gun, but I'm doubtful about whether it is suitable for anything beyond working with wax. As you noted, the prices have gone up, indeed. This all might prove too costly for experimentation for the time being.


I had no idea those materials were the most difficult to weld! In all of the foraging I've done for more information, the consensus seemed to point to relative ease. Thanks for the heads-up, and I'll certainly have a look at PVC.


Many thanks for those great links. I've yet to find much in the way of "plastic" sculpture. My primary interest, for now, is to gauge the durability:cost from those plastics being used in sculpture. Another problem is trying to avoid creating objects that look like assembled waste-plastics.


I don't mind working with either castable or sheet-form long as I can achieve the desired results A few years ago, I made maquettes of large, articulated curves that taper to a point out of saran wrap. I'm looking to replicate these pieces in a material with enough opacity to support digital content projected onto the surface. What I really appreciated about working with the Saran wrap is how quickly I can create these objects. With a basic armature and expanding foam, (dotted along said armature to provide traction for the wrap) I was able to achieve some impressive results. The current issue is finding a suitable, more durable material.

Thanks again for all of your insights!
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Old 05-22-2008, 06:46 AM
PTsideshow PTsideshow is offline
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Re: Welding and fabricating thermoplastics

Here is a site that has the welding kits and filler rods for some along with a small manual for welding.
They also have most everything you would need for fabrication in one spot. Drills sharpened to the correct angle for cutting plastics, saw blades, heating strips etc. Along with a lot of information you can cleaned from the pages.

Check out your local Library for the welding text book has a number of pages on what it is and how to do it.
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been there done that !
I am not a lawyer, and never played one on TV!
All the usual
and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or suggested uses, Wear safety glasses, closed course, professionals only
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Old 05-22-2008, 07:39 AM
grommet grommet is offline
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Re: Welding and fabricating thermoplastics

That's a pretty old copy. Link to newer book, with index.
Modern welding
Taking my own advice
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Old 05-22-2008, 08:35 PM
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obseq obseq is offline
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Re: Welding and fabricating thermoplastics

Glen and Grommet,

Many thanks for the heads-up on that resource!

Following up a bit on this thread, I'm investigating possibilities using filament strand, (nylon, etc) for my purposes. It's a shame that the majority of websites that sell thermoplastics/filament do not have many useful images-- Makes for some difficulty to say the very least.
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