Countersinking and Trimming the Window
I struggled for hours yesterday trying to make countersinks for the #6 screws used to secure the glass to the roll bar. My #6 cuttter wasn't working correctly. It spun without cutting and made shallow holes. Very odd. Something was off. But first, do no harm to the flight article! I finally realized after asking fellow building buddy Craig (A&P/IA) about it that the cutter I was using was dull from countersinking #6 holes in my fiberglass rudder fairing. Fiberglass is very abrasive and hard on tools. Fortunately, Craig had a #6 cutter that I borrowed. After that all proceeded smoothly and I got all the roll bar countersinks done drama free. I learned a lesson there. I still need to do the rear edge countersinks, but they will be much shallower since they only need to accept a #40 dimple. I wanted to move on the front edge trimming. I'd marked the trim line with tape and Van's advised against leaving any tape stuck to the plexiglass for more than 2 days because the adhesive can cause issues. I'm going out of town for 4 days so needed to get it done. I needed to trim anywhere from zero to 3/8" along the front edge. I pondered the options for removing the material. Cutting disc, random orbital palm sander, sanding block? I did some tests on a scrap piece of plexi with a palm sander. It was quick and effective, but the vibration gave me pause. The glass is pretty floppy and flexible, and I was concerned about controlling it while sanding. In the end I opted for a 9" long sanding block and 60 grit paper. It was definitely the slowest method but the most controllable and easy on the material. After several hours of elbow grease and multiple test fitting on the fuselage I got the fit I was looking for on the roll bar. And I could remove the tape. When I return, I'll finish up the rear dimples.
Tapping Rollbar and Upsizing Holes for Countersinking
This post is from Scott's RV-14 Build
Rear Glass Progressing