Countersinking the holes in the plexi glass is next and worries me. I tried practicing with several countersink bits. But the normal 3 blade countersink bit with nipple that I've been using on aluminum all along works the best. The bits that are so called chatterless with lots of blades and no dipple, make chatter marks. So what's with that.
I used the countersink stop for consistancy. The countersinks for the dimpled skin are way deeper than the countersinks for just the screw heads. I used the 1/8 (#30) bit even those these are number 6 screws. Because the plans say to and because this gives just the right size for the screw hole.
I used the electric drill and spun it medium speed. I noticed the plexi glass would melt if I spun the drill to fast.
After countersinking I enlarged all the holes to 5/32 using the plexi glass drill bit.
