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Match drilling aileron counter balance

Michael Burbidge

Well Known Member
Do you have any tips for match drilling the hard steal counter balance through the soft aluminum skins. The drill really wants to wander and the soft aluminum is no match to prevent that.

Michael-
 
How I did it is just one of the many ways, but I drilled just enough to make a centered mark on the steel. I then removed the steel from the leading edge and used an undersized bit on the drill press with as short a shank as possible to drill a pilot hole. I then upsized the hole in the same manner on the drill press. Resulted in very little time exposed to the softer aluminum hole and minimum “wandering” of the drill bit.

But as mentioned, just one method of the many.
 
I used a split-point bit and it wandered anyway. Stainless is stubborn stuff. I got better results as Jon did, using the drill to just barely mark the tube in assembly, then disassemble, get it on a bench or in a vise so you can see what you're doing. Center punch the marks and drill away. Sharp bit, go slow, use oil.
 
For whatever reason a hand drill on low speed, fresh split drill bit and boelube did the trick for me. Made me wonder what the fuss was about.
 
Also there are 3 other threads (now 4) on this issue on page 22-04 of the WING PDF in the WIKI.

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