Plastic Sheet That's Flexible-Machinable-Paintable?

[PrIsMaTiC]

I tried several times to make a 17 x 23" plate out of wood.
The plate has to conform to the irregularities of a tile covered
wall. The sheet rock (wall board) and the tile look fine until
you put a level across the surface. It has more bumps than
than the Rocky Mountains!

I've worked with various types of plastic to make custom
boxes for electronic projects. I'm sure a lot of you have
worked with acrylics like plexiglass. When you heat it up
it can be formed into various shapes.

I need plastic sheet at least 1/4" thick. 3/8 or 1/2 inch would
be better. Its got to be machinable with a router, drill, saw,
etc., and paintable. It does not have to conform to this
bumpy wall perfectly. I'd be happy if it just compressed
into the lumps and bumps to some extent. The acrylics I've
used are just too brittle for this application.

[Externet]

Hi.
To conform a thermo plastic sheet to a surface, it would have to be heated, and to hold it in place during heating, something like turning the wall horizontal would be needed

Another way would be to make a plaster mold of the bumpiness and pour plastic cast to make a mold to make the conformed sheet.... waaaay to complex.

Would that foam backed board used in picture framing be of use, secured to the bumpy wall and the plastic sheet attached onto its flat exterior surface ?
-Or attach a layer of foam or silicone rubber to the plastic sheet to conform to the wall irregularities ?

Miguel

[jwax]

Can you use "Corplast"? It's the corrugated lightweight plastic used on real estate, and political signage.

[MrAl]

Hi there,

You didnt say what you want to use this for did you?
How much weight does it have to support?

[Engineer1138]

1) Build a frame the size & shape of the sheet you need and leave the top open
2) Fix it to the wall temporarily in the desired location, using putty to seal any gaps.
3) Pour liquid castable acrylic into the frame (mold).
4) Let it set and remove the frame.
5) Voila!

[haklesup]

Can you just use a flat piece of plastic or lexan/polycarbonate/plexiglass and then use a flexible adhesive like silicone to fill the void.

Aside from that, I can't see a practical method which does not involve a casting of the wall so you can turn it vertical or fit it onto a vacuum forming table.

AFAIK, vacuum forming will give you the best compliance, but you will need to trim the edges all around. Gravity forming can take a long time and uneven or overheating can damage the material.

I might also look at getting some drywall mud and skim coating the wall to flatten it before making your project.

[Chris Smith]

Styrofoam.

Possibly heat and vacuum applied, but Styrofoam.

Not all Styrofoam is like the coffee cup, and most like the kids game is vacuum and heat applied plastics.

You can use a hair dryer and tape to seal it from the air, plus a shop vac to pressure contour it, ......so a sheet of Styrofoam with or with out the air bubbles build in should do just right?

[Lenp]

I assume that you need a stable mounting surface for the plastic sheet. Why not coat the rear of the plastic sheet with auto body filler, like Bondo. When it cures it will harden. I would deeply sand the wall side of the plate for good adhesion first. When pressed to the surface it will fill the low spots and average them all out. If you need the plate to be removable, cover the wall area with thin plastic film before pressing the plate. The finished plate will be in conformance with the wall irregularities. A similar technique is used, at floor level, for setting and leveling machinery on uneven floors, it is called a bedding compound and it is pourable.

As for the plastic, I would consider sheet PVC. Available in many thicknesses, it can be glued, stacked and clamped to get odd thicknesses, worked with common woodworking tools, hot bent, drilled, tapped, sanded, painted and is available from many suppliers. We use www.usplastic.com with good service. (Their web shipping costs are way off since they use a % of order cost not weight so look it up then call them to order) or www.msccirect.com

Len

[Chris Smith]

Actually its Styrene not Styrofoam. [no air or foam]

If you don’t layer the Styrene and you try 1/4" acrylics, you’ll need a commercial vac to mold it into shape, and a heat supply that will do the job with out burning the plastics.

You can however use Styrene sheets in layers as thin as 50 thou or more, and glue many layers together to form a strong veneered plastic sheet exactly like plywood.

This doesn’t require nearly as much vac and heat work as any hair dryer and shop vac will do.

Also the other useful form you can use is ABS, also a styrene.

Acrylonitrile butadiene styrene