17 Feb 08

I sanded the body master mold for about an hour to start the morning. This is one of those things that will only get better and better the more I work on it, but I have to pick a stopping place at some point. Deciding when this is can be difficult, but it will definitely be soon. The surfaces are all excellent, actually better than what will transfer to the wood, but it's just so hard to see some microscopic imperfection and not fix it. Anyway, we did more important stuff today.
We finally got a windshield cut successfully. The 8th time was a charm. We masked off the area we wanted to save with a combination of electrical tape, double-stick vacuum-bagging tape, shower pan liner, and 4mil polyethylene. The windshield is made of safety glass, so we had to use a little logic to do this correctly. Since safety glass is made by using 2 seperate pieces of glass that sandwich a flexible plastic sheet, we sandblasted through the top glass up to the plastic and stopped. We have had problems in the past with the glass not being supported as it is cut which causes the trimmed piece to overstress and crack the remaining windshield piece. To hedge against this, we hot-glued wood blocks spanning the cut line we had just made. We then flipped the glass over, remasked the bottom side, and sandblasted all the way to the plastic layer again. This left us with the plastic layer remaining, which we cut with a razor knife. Free at last. We used our 3"X24" belt sander to treat the edges of the windshield to smooth everything out and protect against hairline cracks forming later. All done, right?
I wish it were that easy. When we put the windshield up to the master body mold, we found that it was a long way from fitting. We had been using Pilkington brand windshield all along, and this is what we had planned for. This piece of glass was a Chrysler part, but since it was for the same vehicle as the Pilkingtons, we figured it would fit without issue. Wrong. When the cut windshield didn't fit our body mold, I put it up against a Pilkington that I had waiting in reserve. It was about 1/4" different in curvature in some places. I found this to be a serious bummer and a serious buzzkill after finally cutting a windshield with success. The good news is that we feel pretty confident that we can repeat the success with reasonable regularity, so we will tackle the Pilkington tomorrow and really put our new process to the test.