Hi!
I have read a lot of posts, mainly about Cars, but this appllies to Planes( mainly Canopies) and those who have a Submarine with a clear side. This can be daunting, but it can be done. First, if you want to cut uncovered windows in that clear side You have to decide how large you want those windows. Personally I would just paint the side Masking where you want the windows and then over spray the side with clear Semi-Gloss and after it dries a few days, Buff it with a wee bit of polishing compound. Problem solved and no cutting! remember, if it feels Brittle it is!
If you are of the school of, I must cut, heres what you do. Remember, If it feels Brittle it is. DO NOT press to hard. First Lay out the windows on the OUTSIDE! Leave the inside alone. You do this by taking Wide masking tape and cover the outside. Cover the inside Only AFTER you have marked out the windows. Now comes the hard part. You must leave yourself a little wiggle room. Make the windows a wee bit smaller than you want. This gives you room to sand and finish the edges bettter.
I hope you have some P.E. saws. Remember if it feels Brittle it is. This is going to be a long careful process. The most important move here is holes. You must drill holes at all four corners of each window. This is tricky. DO NOT use anything above a .0292 or #69 drill bit in your Pin Vise. You want rounded corners? Then follow the curve with this drill bit until the curve is complete with nice neat holes. Then With a Brand New #11 blade carefully connect the holes and there you have your rough cut curves.
The straights are different. But one Thing through all of this DO NOT press to hard! For instance when drilling let the drill rest on the surface lightly and turn gently and straight. That part is the same In all your manouerves. Remember one very important thing. If it feels brittle it is! Any undue pressure WILL cause starring in the plastic far from where you are working. So, don't press to hard. Take the biggest P.E. saw you have and gently cut the straights, Inside the lines just a wee bit!
There, you've done it! Now carefully and gently sand the holes until you are on the lines you want. Finish them out to where you want. Do you want rounded edges or straight sharp edges? Either way be carefull and finish them out gradually from 320 to 1500 grit WET. Now after the last sanding. Polish those edges til they are fairly clear. Okay, now GENTLY remove All the tape from outside first. Then the inside, GENTLY remember!! Looks good doesn't it? Install it and be proud of what you did. Brittleness shouldn't stand in your way so don't let it.
Tanker-Builder.