I decided, since I am using the same glass as the salon windows, that I would mount it the same way as well. Instead of screws I will glue the piece of plexiglass in place with Dow Corning 795 (but in this case I'm thinking of using white and not black). In order to accomplish this I need to cut a hole in the top with a flange that will allow the glass to sit recessed in the hole. I will be using a router to cut the hole and then cut a larger hole half-way through the top.
We picked up some 1/8 inch thick lauan plywood and created a router template. I drew two rounded rectangles on the plywood that represented the full hole and the flange. I then cut out the smaller hole with a jigsaw and smoothed it as needed with a little sanding. I positioned it on the top at the correct location (a bit forward of the current window to accommodate solar panels) and attached a board to make it easy to re-position as well as clamp. Using a template guide in the router I cut the smaller hole. It took two passes with the router in order to cut all the way through the top, and I had to remove the template for the second cut and let the first cut be the guide.
|Window template inner circle cut.|
Not sure if the cat is trying to help or just wants attention.
After cutting the hole, I then cut the larger hole in the template. Resetting the router depth, I could then cut out the flange. Using a 1/4 inch straight cutting bit took a little while to clear out the material in the flange, but it worked well. I used a round-over bit to round the outer edges and sandpaper to round the foam edges.
|Cutting the window flange.|
The next day we did what I hope will be the last fiberglass layup of this project. Having just cut a big hole in the top and exposing the foam core, it now needed to be covered in fiberglass. We sanded down the area around the hole on the bottom side to remove the finish (yes, the one we just applied) and allow for the fiberglass. We cut strips of the 10 ounce fabric to cover the straight sides of the hole and chopped strand mat for the corners. The temperature was, surprisingly, in the 70's and so we got the fiberglass applied. Of course, by the time we were finished, the sun was setting and the temperature started to drop. Out came the propane heater to keep the temperatures up and allow it to cure.
|Window opening covered with fiberglass.|
In addition the the hole, the template was also used to cut the plexiglass for the window. By using the larger template hole and a larger diameter template guide, we could cut a window panel that gives about 3/8 of an inch of clearance inside the hole...just enough for the sealant to glue the panel in place.
The next day or two I expect we will be doing a lot of sanding (oh boy), hope it goes well...and quickly.