EAA Sport Aviation

SHEET METAL SCREWS

BY NIEL PETERSEN, EAA 35302

IF YOU HAVE SELF-TAPPING Phillips head sheet metal screws to install, this is a scheme I discovered that saved me a lot of frustration with stripped-out screw heads and damaged driver bits. I put a very small amount of anti-seize paste on the end of the first screw before trying to drive it. The use of anti-seize paste on the screw made the initial drive much easier, and I even found that I could make the pilot drill hole slightly undersize using number drills to get me a better thread engagement.

If, like me, you have a lot of self-tapped screw holes, consider grinding the head of a longer screw of the same thread so that the head is three-sided and can be chucked in a hand drill. This makes the initial threading a simple and fast job when a line of screws must be installed. I used a hand drill for better control, although an electric drill could be used, but only with great care.

I found the longer chucked tapping screw easily lasted for more than 50 holes in both steel and aluminum, with no observable degradation, but it is necessary to add anti-seize to the tip after each tapped hole to prevent the drive friction from returning. I used a tiny amount of anti-seize in a small cap and just touched the screw in no more than 1/16 inch.

It is very important, though, that when you drive any screw with a Phillips driver, that you don’t have any anti-seize on the screw, on the driver, or even on your hands, or the driver will cam out of the screw head and wreck both the screw and the driver.

Using this technique it was easy to get consistently high-quality self-tapping threads throughout my J-4A. Try it. You’ll be amazed by what anti-seize can do.

COUNTERING
COUNTERWEIGHT

BY J.D. WOODS, EAA 89812

BUILDERS WHO INTEND TO paint their project sometimes realize that finding a way to hold the parts for painting or curing requires inventive solutions. In some cases, the solution is obvious—such as an aileron that can have a rod through the counterweight to support it while in the booth.

A part such as an elevator presents a challenge since the counterweight dictates how the part will hang. If hung by the bearings, the elevator rotates down toward the counterweight, and there is no simple way to attach a hanger to the counterweight. The solution is to overpower the counterweight, and, as shown in the picture, the elevator will hang trailing edge down and be stable. Any suitable weight will do, and in this case, I used water in a milk container.