[CQ-Contest] Aluminum fatigue cracks and scratches - treatment?

[Bill Coleman]

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 at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901