Another Tip-up Canopy Question

Building an RV7 in Indianapolis. Getting ready to rivet the C702 fwd skin to the WD-716 frame. Part of the WD716 frame is a 1/2" aluminum tube that rivets to the skin using CS4-4 blind rivets. My question is this: Do you countersink the 1/2" tube to fit the skin which has been dimpled for the CS4-4 rivet? The tube looks to thin to countersink and I'm worried about opening up the hole so much the CS4-4 rivet won't hold. Thanks in advance.

Mark Rinehart

I thought that was 3/8" dia tube. In any case, you want a very small edge relief on the tube to accommodate the dimple in the skin. You are correct in that you don't want to open up the hole in the frame tube.

Make a test coupon of each piece and see what a slight counter sink will get you.

...Or...don't bother with dimpling the skin and use LP4-4s and slap a piece of carpet on the glareshield...

Cheers!

What Brian said. If the skin has already been dimpled, just barely countersink the tube hole for about 30% of the dimple.

Thanks to all for the feedback!
I wish the RV7 manual was a little more descriptive of these kinds of details.

Mark Rinehart

Shape of tube

Speaking from a very annoying experience; Be sure to check the frame fits over the instrument panel as expected. Mine didn't and I had to make a new tube and get it welded.
First time I have seen such poor work from Vans.

Good time to paint the glareshield.