Make your own composite sheets.

[bizzybody]

You want to use some fancy fiberglass sheet for a new chassis but the price of FR4 or similar stuff makes your wallet cry?

Here's a way to make your own on the cheap.

Wal-Mart, K-Mart, other superstores, hardware stores, paint stores and other places usually have small kits for fiberglass patching.

These kits will have either a piece of glass matting (it's all random fibers held together with a binder that dissolves in polyester resin) or woven roving, which looks like very coarse cloth. Get the kit with the woven glass.

There will also be a small can of resin and a clear tube of MEK catalyst. (Methyl Ethyl Ketone, for the chemistry curious.)

The next item you'll need are a pair of surfaces that're smooth and very rigid. Some aluminum plate will do (look in your phone book under scrapyards or metal recycling) or a couple of pieces of sink cutout from a kitchen countertop.

Item three, some heavy plastic sheeting like Visqueen or pond liner or that black stuff used to keep weeds and grass from growing around trees.

Item four, three large spring clamps.

Item five, a pair of latex, of better- blue nitrile, gloves.

Check your surfaces to make sure they're FLAT. If they don't fit perfectly together, your fiberglass sheet won't be flat and even.

Now let's make some small sheets, perfect for a ZipZap or Bit.

Cut six pieces of roving about 2x3 inches.

Cut two pieces of the plastic sheeting, large enough to cover your flat surfaces and a bit past the edges. (Make sure not to have any creases in the part you're using.)

Lay one plastic sheet over one surface.

Put on the gloves.

Mix up some resin in a small plastic tub like a margarine tub (washed to get all the greasy margarine out!). DO NOT use cheap plastic drinking cups or styrofoam cotainers. Polyester resin dissolves styrene plastics! You'll have a very nasty mess to clean up. (Or carpet to replace...)

Pour out a little of the resin in three spots, spaced to form the corners of a triangle.

Lay one piece of roving onto each of the daubs of resin and use a popsicle stick to smush the glass down into it. Keep the weave straight and don't poke holes through it.

Pour some more resin onto the glass, dribble it onto any dry spots so the whole piece is wetted.

Lay the other pieces of roving on top of the first ones and pour on more resin to fully wet them.

Lay the other piece of plastic sheeting on top of the glass and resin then smooth it down to push out air bubbles. (Clear plastic is best so you can see when the bubbles are out.

Place the other surface on then apply one of the spring clamps by each of the places where you have the glass in this sandwich.

Weather and temperature will affect how long the resin takes to cure, placing this out in the hot sun will speed cure, while cold and damp may make the resin take several days to cure. (I once tried to do fiberglass work in the middle of winter in an unheated shop and the resin never did cure on that item!)

The reason for making three pieces of fiberglass sheet is because along with the three clamps, it clamps evenly automatically. It's like a tripod or three leg table. It can't rock or wobble.

If you want a larger sheet of fiberglass, cut roving large enough to cover the whole of your clamping surfaces. Making it thicker is easy too, just lay up more layers of roving, but don't try for more than four at once, especially when doing one large sheet. If you need to add to or laminate two sheets together, clean the surface with acetone, let dry, sand with coarse sandpaper then clean again with acetone.