SuperTruck: Foam Bed Cover Continues

by Ben N on November 27, 2012


Did some carving today… Not Turkey, styrofoam!

I took a look at a few different ways of cutting the foam. I started with a home-built hot wire cutter. It didn’t work as well as I hoped. I used a heating wire from an old electric space heater. That is a flat wire. It cut great on edge, but would always kinda fold over, so it was hard for me to cut a straight line with it.

I also tried just a plain old hand saw. That actually worked great (other than the great snow-storm of white plastic dust!) Foam is so easy to cut that a power tool doesn’t really have any advantage, and a manual hand tool has better control over speed and direction.

I used the hand-saw to cut an angle on both sides of the foam cover.

To start smoothing it out, I borrowed a belt sander and hooked it up to my shop vac. The dust port on the sander was a completely different size than my vac hose, so connecting the two wasn’t ideal. Still, it worked well enough to do some sanding while controlling the dust.

Also, when I borrowed the sander from my Dad, he gave me what was left of some fiberglassing supplies from when he glassed his duck-boat. That was most of a gallon of resin and a pretty-good-sized piece of cloth.

The edge of the foam, where it rested on the side of the truck wasn’t as good as I’d like it to be. Ideally, it would be nice for the cover to have a bit of a lip to it. I also hacked the one side a bit, so I thought it would be nice if I could somehow extend the edge a small amount. I still needed to glue the two halves together, so I decided to kill two birds with one stone by getting a can of Great-Stuff, glueing both parts with it, and adding a lip to the edge of my white foam board.

I recently heard about using aluminum foil and a release agent to use as a form for making fiberglass shapes. Since I was already in the kitchen getting the aluminum foil, I grabbed some PAM brand cooking spray for the release agent.

I put a layer of aluminum foil on the rails of the truck, and sprayed it with PAM, the set down the foam cover and ran a bead of Great Stuff in the seam and down both edges.

I then set a few weights on the cover to hold everything in place while it cures.

My small test with white school glue worked well as a sealant. While I was at the hardware store getting the spray foam, I priced out a gallon of glue. The fancy weather resistant glue was $30 a gallon – still far cheaper than urethane resin!

My Dad also had some sealant he used to seal up some walls before applying a fancy drywall finish. He gave me the rest of the gallon to test with my fiberglass experiments. It’s called GARDZ, and is very thin and easy to spread. Much easier to work with than glue. I brushed some on a a piece of test foam. It’s drying even as I type this.

I’m hoping that I should be able to carve and sand the Great Stuff once it’s cured and fiberglass over the GARDZ sample.

I’m still not sure what method I’ll use to actually attach the cover to the truck. I’d like to make it easy to both flip up OR completely remove, without making too many screw and bolt holes in the truck!

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