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Matus1976
Hello physforum - I'm looking for a plastic that has properties to basically use it as a substitute for wood in one particular application, that being the backing for a chair. I'm making myself a new computer chair and don't have the heart to use wood as the backing material for my hi tech aluminum and viscoelastic foam chair. Typically one would wrap the cloth around the foam and fasten it to the backing board, usually wood. I'm looking for a plastic then that is available as a sheet which is stiff, but is also 'soft' enough to nail or staple. I tried PVC and it was too hard. I was purusing the plastic types over at smallpartsinc but the property descriptions were not detailed enough. Polycarbonate and lexane are too brittle. PVC is too hard and I'm thinking PEX and CPVC will be as well. Perhaps ABS? any thoughts?

Thanks!
xtrmn8r
Don't know if it comes in a usable form for your project but maybe it can be cut to size.

http://www.trex.com/

Damn. Just occured to me this may be spam. dry.gif
fizzeksman

Hello Matus 1976

Just go down to he local builders supply and get some "vinyl boards". They are available in many different sizes and shapes, and can be used for trim, fencing, or a multitude of other projects... chair backs perhaps.

Jack
Matus1976
QUOTE (xtrmn8r+May 14 2008, 09:08 PM)
Don't know if it comes in a usable form for your project but maybe it can be cut to size.

http://www.trex.com/

Damn. Just occured to me this may be spam. dry.gif

Yeah I'm not looking for actual wood looking plastic, i'd prefer it look completely 'un natural' but I might have to end up going with something like this.

Spam? I am spam or that trex site? man, I'm not spam! I swear! =P

I think I'll order a few samples from small parts inc online and just try nailing them.
Matus1976
QUOTE (fizzeksman+May 15 2008, 03:47 AM)
Hello Matus 1976

Just go down to he local builders supply and get some "vinyl boards". They are available in many different sizes and shapes, and can be used for trim, fencing, or a multitude of other projects... chair backs perhaps.

Jack

Ah that's perfect! Now that you say that I remember my friends new house, all the railings and trim were done with hard white plastic and they were screwed and I think nailed as well. Would a local builders supply place have these boards in the equivalent of 'plywood' like sheets, e.g. 2'x2' and 1/4" thick, etc. I can't recall having seen them in anything other than pre fabricated stair and porch railings or fences, etc. Thanks though, excellent tip. I'll see what I can find.
Enthalpy
Vinyl is PVC (or PVA).

ABS is softer and, very important, not brittle. So is polypropylene (PP). Polyamides (PA) are good also.

I wouldn't nail nor staple any plastic, less so to sit on it - maybe screw. You can glue ABS or PVC or also PA but not PP. You can solder them all; special apparatus is available to solder PP and is easy to use. Relatively good glues are available for PVC pipes; ventilate the working place the big way.

Take BIG safety margins with plastics. They're unpredictable and sly. Far less easy than metals, as they creep and may be brittle (PVC will split if you nail it).

Take HUGE safety margins if gluing, and big ones if soldering.

Could you make your chair with a frame of PVC pipes? Available in many diameters as water pipes +tubes are a mechanically sound shape +bends and tees etc available +gluing fitted tubes is safer +easily done, just cut the tubes at length. The result will be lighter and more robust than cut sheets.

By far my preferred solution for a DIY chair.

Or do the same with copper or brass pipes and their hardware. Can be welded, then - if needed - covered with nickel, chrome or paint. You can even bend copper pipes with the adequate apparatus.

What about letting your plumber assemble the frame to you drawings?
Smurof
Don,t forget GRP - Glass Reinforced plastic.
If you have a suitable shape, eg old chair back you can make a mould from it.
You can use polyethylene sheet to prevent adhesion.
Lay up the polyester resin and fiberglass sheets in layers on the mould, allowing them to cure between layers. Only do this in a ventilated area and wear mask so you dont breathe in glass fibre particles and fumes from the resin and activating agents/catalysts.
Build up the thickness you need. Trim the edges and seal with resin.
Car body shops should be able to supply you with the materials.
Falconer13
Lexan might work as well. It is incredibly durable, I think it can be molded when heated, and it can be riveted and drilled with relative ease. Biggest problem is is that it is usually clear, and it scratches easily. But if you get a thick enough sheet, it will stop up to a .30 caliber round from penetrating.
2TALLTARY
I agree lexan or polycarbonate is your best bet. Acrylic is the brittle material. Polycarbonate is a very strong durable material. You can hammer a nail and it will go right through and it is bulletproof. Found a website with some more info that might help you...iplasticsupply
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