Drilling a Straight Hole in Aluminum.


One of the fundamental skills a builder needs to develop on just about any airplane project is drilling a clean, straight, well-centered hole in aluminum sheet. No matter what materials are in your airplane’s basic structure, you’ll have some aluminum somewhere—in engine baffles, for instance. Knowing how to get that hole where you want it, cleanly, is important.

1. The first step is to make sure the hole is properly positioned. A sure way to do this is with an automatic center punch (available at your big-box hardware store). Place the sharp point right on your mark and give it a snap; your drill bit now has a place to start.

2. Lining the drill up straight is the key to making sure that the hole is clean and where you want it. Alclad aluminum makes this easy with its reflective finish—it is almost like cheating! In this picture, you can see that the drill bit and its reflection are not aligned; this means it isn’t going to go straight and might even skip out of the center-punched dimple.

3. Move the drill motor around until the reflection of the bit is aligned with the bit itself—it should look like a long extension of the bit.

4. If you do this in both the vertical and horizontal directions (and keep it that way as you drill), you’ll have a hole that you can be proud of.

If you are new to working with aircraft aluminum, it pays to use some scraps and practice before working with actual parts from your kit that are intended to go on the airplane. Sloppy work on the airplane is usually a sign to a technical counselor that the builder was in too big of a hurry to practice.

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Paul Dye
Paul Dye, KITPLANES® Editor at Large, retired as a Lead Flight Director for NASA’s Human Space Flight program, with 40 years of aerospace experience on everything from Cubs to the Space Shuttle. An avid homebuilder, he began flying and working on airplanes as a teen and has experience with a wide range of construction techniques and materials. He flies an RV-8 and SubSonex jet that he built, an RV-3 that he built with his pilot wife, as well as a Dream Tundra and an electric Xenos motorglider they completed. Currently, they are building an F1 Rocket. A commercially licensed pilot, he has logged over 6000 hours in many different types of aircraft and is an A&P, FAA DAR, EAA Tech Counselor and Flight Advisor; he was formerly a member of the Homebuilder’s Council. He consults and collaborates in aerospace operations and flight-testing projects across the country.


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