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.
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.
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