New Refer Lid
This past year I installed a new Tru-Blu 12 volt holding plate freezer/refer system, installed 2″ of insulation throughout the refer and covered it all with new glass. One problem remained though, the holding plate keeps frosting up reducing its efficiency. The problem is the old refer lid, made of two parts with a hinge in the middle doesn’t close tight enough allowing in warm air that turns to frost on the freezer plate. So over the past few weeks I have been working on building a new refer lid. The new one will be one piece, and being fiberglass will not change shape, be easier to clean and will sit right on the lid gaskets to make a better air tight seal.
Since the bottom of the lid will be fiberglass with insulation inside I have had to start by building a “plug” or exact copy of what the finished part will look like from which I will make a mold from which the finished part will come.
I’ve had to do it somewhat the old fashion way as I don’t have a computer design program nor a five head cutter to cut the plug out of a block of wood. So, using plywood and some pine I first made the exact part I want to eventually have out of fiberglass. I then applied a couple of coats of polyester resin and sanded it smooth, filled any hollows with fairing compound before apply white gel coat.
Once the gelcoat was set I applied a blue trace coat made up of acetone and Dykem Dye (a liquid machinists dye). This trace coat dries rapidly and once dry is sanded until the blue is gone with 100-120 grit paper. This initial gelcoating highlighted problem areas, places that were hollow, high or just plain voids, which were then taken care off by either sanding or filling. The areas this first gelcoating reveled are hard to see until an even coating of one color is applied.
Once the first gelcoat was sanded and problems taken care off second coat of gelcoat was applied, again it was dyed, sanded with 120 grit paper, dying and sanding was repeated with 220, 320, 400 and 600 grit paper. By applying dye and then sanding it off with each grit allows you to take out just the sanding scratches from each prior sanding, thus removing only as much gelcoat as necessary.
After 600 grit the plug was compounded and at the picture stage here has been waxed with mold release wax, it is now ready for PVA (a mold release agent) and gelcoat. If this was a mold for a finished part like a deck or hull it would have been sanded to 800 or higher, machine compounded to 1200 grit and then waxed to a glossy finish. Since this is a part that is only seen when the refer is opened I only went to 600 grit, just enough to ensure the part would release from the mold and that any remaining sanding scratches would be too small to hold refer mold and nearly invisible.
Building parts out of fiberglass that require a shiny gelcoated finish have always been time-consuming, this project so far has taken 16 hours.
Next step gelcoating and fiberglass for the mold.