Working skin fit issue

I’ve been trading emails back and forth with TAF regarding the fit of my bottom skins on the main spars. The spacing of the holes is off, so I can’t get the skin to fit without some kind of fix. The skin is not supposed to be under any stress. On the other hand, input from other builders was that I should check with the factory before elongating any holes, since I don’t know if the wing strength will be compromised at all.

When I start putting in rivets like this, they’ll fit fine for a while, then stop fitting…
… and by the end of the wing, the holes are off by quite a bit, about 1/8″

The alignment is not off by a lot – it’s all of 5/64″ by the end of the wing skin, which doesn’t sound like a lot – but, you can see the result, and it’s enough that I can’t fit rivets in. I can’t really bend anything to make it fit better, since this is a straight line of holes along the spar cap, which is pretty beefy. Mike Blyth had me check the hole pitch on both the skins and the spar cap to find out which is the culprit – in my case, it looks like the skins are a little off from the nonimal 2.0/3.0cm spacing, whereas the spars measure more closely to nominal.

So for the moment, attachment of bottom skin is on hold until I work out a solution with TAF. Meanwhile, I have some fresh tank sealant on the way so that I can start building the fuel tanks. I also have all the replacement parts I need to finish the empennage so I might work on that too.

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