I try to post updates only for completed projects, and since I’ve had several projects in progress it’s been a while since I’ve blogged. The diffuser is finally finished, so here are some pix and a video that explains it all:
Time to lay up the first set of body panels. In some photos you can see the joggles laid into the molds with duct tape so the panels will overlap smoothly. Nine coats of mold release wax and there were no problems releasing parts from the molds, although at times I did have to work a bit. Each mold required about a day of finishing work to remove ripples due to waviness in the body buck. As I’ve said before, don’t build a body buck the way I did it. Instead, immediately after completing the X-Y grid of cross sections, lay about 3mm of fiberglass on top to give a good solid surface, then use body putty on top of that. You’ll be finished in half the time it took me. The only place you should use foam is where actual carving is required due to the complexity of the shape, like the sidepod air inlets. Yes, I know the main roll hoop forward braces are still not there. Patience…
One problem I found out the hard way is that a chemical in some brands of duct tape inhibits gelcoat curing. In the end, gelcoat that had been in contact with some kinds of duct tape never fully cured and had to be cleaned out with acetone. Also, the joggles formed with duct tape were too sharp for the fiberglass mat to conform to, resulting in bubbles under the gelcoat that have to be scraped out and reworked. Gelcoat is probably more trouble than it’s worth given its weight, so next time I’ll just prime and paint the body panels to finish them. The sharp joggle corners need to be filled in with fiberglass roving before laying mat on top.
Probably the main thing to explain here is how I create the overlaps in the molds. The edge of a mold is marked on the body buck with duct tape, which will leave an impression in the mold for later trimming of the finished part. Then after removing the mold from the buck, I lay in a strip of 1″ duct tape touching the existing tape, then another strip touching that one. I then remove the first two strips of tape, leaving the edge for the next mold with a 1″ overlap.
Time to make molds!