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Log Entries for Ribs


Log Entry Date: Apr 25, 2012

Ribs

Drill holes for aileron counter-weight
After a horrible 3 week cold that turned into a nasty two week viral ear infection followed by two weeks of travel for work and two weeks of catching up, I'm finally back to working on airplane parts.

As usual I screwed them up too. The challenge is to drill a 3/4 inch hole in the front of the aileron nose rib so an aluminum tube filled with lead can be slid in there as a counter weight. It gives the airplane a lighter feel and has something to do with preventing flutter.

I took a 3/4" OD washer with a small hole, laid it on the aileron rib and marked the center of the hole. Then I put that rib on the drill press and clamped a carpenters square to the table so each subsequent rib would line up exactly the same.

That's all great BUT there are left and right aileron ribs. Four of each are used with each aileron. Being an idiot I just repeated my process above for the second set of aileron ribs and of course when I was done drilling those my holes didn't line up.

A better solution would have been to mark one rib as I did with the washer, but then align a left and right rib back to back and drill a 1/8" hole through both ribs in the exact same spot I marked. I could have then set up my carpenters square for both ribs using the exact same reference point.

As it turned out, a slight variation in the bend of the tab and side along with a slight variation in the placement of the washer and a slight variation in hitting the exact center of my mark turned into a 1/16" to 3/32" variance.

I'll have to make one set of holes oblong tomorrow. Once the tube is in I plan to take JB Weld to fill in the little gap just because it'll drive me nuts knowing it's there.
Marking the aileron ribs with a 3/4" OD washer.
My fancy "jig" for drilling. Clamp a carpenters square to the drill press.
Me happy with my work... before I checked it.

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