The bottom skins have a length of j-channel running down the middle to stiffen the skins. in a slow build, the plans call for these to be match drilled against the spar early in the build. With quick build, there isn’t a great way to do that, so I have to carefully install the channel, then the skin, and then match drill from the skin. I didn’t realize the j-channel wasn’t match drilled, or I would have done this much earlier before I had dimples the skin. Anyway, I installed the channel and spent time carefully aligning everything and then match drilling the right wing outer bottom skin to the j-channel. I didn’t finish the whole thing, but should get it done tomorrow.
Because I have dimpled already, I had to go much slower. The problem is that dimpling stretches the hole diameter, about two drill sizes larger. So match drilling with a #40 drill bit is too sloppy and inaccurate. To account for this, I used a #38 drill bit to start the hole, really just to put a center point on the channel. Then I switched to a #60 drill bit, and made a tiny pilot hole in the center. Then I stepped up the hole to #40. For each hole, I’m drilling 4 different holes, so it’s slow but the results are good.
