Replacing Lexan (Polycarbonate) Windshield - Lessons Learned
I replaced my existing Lexan (Polycarbonate) windshield after reading several posts on the forum and watching a Youtube video (I am not the original builder). I concluded that replacing the Lexan with the pre-formed acrylic windshield was risky due to several members breaking their new windshields in the process of installation. So I went to a local supplier and purchased a 4x8 sheet of .093 thickness Lexan for $77. Some have used .062 (1/16) and others have used .125 (1/8). I thought .062 was too thin, and in the video installation of .125 the installer had a difficult time bending the thicker material, so using .093 (recommended by the factory) seemed to be a good choice. Using some old scrap, I discovered that a sharp twist drill bit would suffice for drilling the Lexan. A sharp wood scroll saw blade worked very well for the various cuts. First I heated up the old windshield so it would lay down flat on the new piece for tracing. All but two holes lined up perfectly during installation. After making the cuts I hand-sanded the edges with 150 grit sandpaper, and used a taper bit on the holes (both sides) to reduce the possibility of future cracks. Lexan is susceptible to cracking if the hold down screws are too tight or there is not enough room in the screw holes to allow the Lexan to expand and contract. Holes were about 1/16 oversize to allow for movement. Once I screwed down the lexan on top of the fuselage, I used a rope (ratcheting straps would also work) to bend the Lexan down to the door posts. However, there was no way to get the Lexan into the slot without heating it. During testing I found that Lexan will bend easily if heated with a heat gun, but will start to bubble if heated too much. I partially removed the protective plastic cover (outside only) near the corners and heated up the lexan, which immediately relaxed the material enough to move it into the slot in the door post. There are two problems with Lexan. You cannot polish out scratches. I tried. Maybe someone here can suggest a process that works well. The other issue is the small cracks that form over time due to the bending of the material. In my old windshield, I noticed that the cracks formed several inches from the corners where the sharpest bends were. My theory is that the Lexan was previously heated at the corners only, and not the area 3 inches away from the corners. So I spent a lot of time heating a large area of the windshield in the hope that the material will not crack in the future. Side note: I also painted all the interior support tubes flat black to minimize glare, which was pretty substantial when they were painted yellow. A new windshield sure does look good.
20211212_152753.jpg20211216_114142.jpg20211216_164311.jpg
Reply With Quote
Originally Posted by 109JB
