March 4, 2007 - Countersinking Mania

It was too windy to go flying this Sunday, but I had a productive day prepping the canopy frame and skin for riveting.  I wasn't sure if I should dimple or countersink the side skirts.  The canopy frame side wildments seemed fairly thick so I tried countersinking one hole.  It worked fine.  So I countersunk the two lower rows on the side weldments.
Then I dimpled the side skirts, the lower two rows to #40, and the top row for a #6 screw. 
You don't believe me?  Here's a close-up/
Next I countersunk the canopy frame itself.  The canopy frame was thick enough to countersink, but not thick enough to prevent chattering by the countersink bit.  I solved that by using a little bit of angle -- seen sitting on the top of a rib -- which I would hold underneath the hole for backing. 
I countersunk the canopy frame until about 1PM, when I drove out to Essex Skypark to do a little maintenance on the Citabria.  It was cold and windy and the skypark was deserted.  Here the Citabria sits forlornly, wanting to fly.  I recharged the left brake.   
The skypark wasn't quite deserted.  This is Tiger, the airport cat.
Too windy to fly,  too cold to want to.  No place to go, anyways.    I need to live in one of those airport communities in Florida!
Upon returning home, it was back to work building an airplane.  The canopy skin "ears" need trimming -- indicated by the purple line -- so they will be aligned horizontally with the side skirts.
I trimmed the canopy skin ears, deburred all the holes and dimpled the #40 holes.  I couldn't reach a few of them with the Main Squeeze, so Lynnette helped me dimple them with the C-frame.  It's been awhile since I've done this type of work.  It was fun.
I clecoed the canopy skin back on.  Notice the gap between the canopy skin and the forward skin.  This is common, I understand.  What I'll do is put a shim under the forward skin so it is the same level as the canopy skin. 
The right side has a gap too, but not as bad as the left. 
I had wondered how to handle the rear row of holes on the canopy skin, which are #30 and are filled with flush pop-rivets.  Dimple or countersink?   There is just an aluminum tube underneath.  Dimpling the skin and countersinking the tube didn't seem like it would work.  I did a search on the Vans Air Force forums and the answer was to countersink the canopy skin and underlying tube simultaneously.  So that's what I did.  It should work fine. 
 
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