On Aug 5, 2004, at 10:01 PM, Eric Scace K3NA wrote:
Cracks due to resonances and vibration-induced fatigue can be
halted. Drill a small hole at the end of the crack (the end which
is propagating into the heart of the tubing) clear through the wall of
the aluminum. It is more difficult for a tear to continue to
develop past the hole. (This technique is often used in cymbals,
where a poor-quality casting can cause the outer edge of the
cymbal to crack due to fatigue. Works like a champ.)
This technique is also used in aircraft. In light aircraft, it is not
unusual to see three or four small cracks in high-vibration areas (such
as the engine cowling) stop-drilled in this manner.
This technique is also effective with acrylic.
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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