I don’t have a large air compressor or pneumatic tools so I’m build my plane using electric drills. When it came time to drill holes in the rib webs for the control cable guides I discovered that the location of the holes prevented me from drilling them with my either of my electric drills. They were too close to the wing spar to get the drill in there square to the web. I had the same problem drilling the holes in the rib webs for the aileron and flap hinges. I was able to drill those holes by using my Dremel tool with a #30 drill bit. The holes for the cable guides are 5/16 inch. There’s no way to use a Dremel tool with that large a bit. I found this angle adapter at a local hardware store. It’s made by Milwaukee, uses ¼ inch hex drive bits and worked well for drilling through the plywood rib webs. It cost about $30 here in Alaska so it’s probably $20 in the lower 48.
