I'm drilling some holes in the fuselage frames and spars for the rudder cables, battery cables, and other stuff. Some of the holes go at an angle, so my drill press is not much help.
For the smaller holes, the portable drill guide works fine. This has an adjustable base, so it can be set for small angles.
The drill guide has a 3/8" chuck, so for bigger holes, I used an idea in the latest EAA magazine. To drill a 1/2" hole, I started with a piece of 3/8" pipe, and drilled it out with a 1/2" bit. Then I welded up a "C" with two bolts and a piece of scrap, and brazed the pipe in place. Next, I cut out the pipe so it would fit over the spar. Mark and pilot drill the holes on both sides of the spar. Insert a 1/2" bit backwards in one end to position the guide at the correct angle (15 degrees for this one), and start drilling through the pilot hole on the other side. In the picture, it looks like one long drill bit, but it really is two bits. Kind of reminds me of a magic trick.
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