2/25/2008 Right Spar, C-Sink Tank Attach Holes - 2.5 hours Today I officially started on the wings. I grabbed the spar that was on top (the right one) and started working on the tank attach holes. I have decided to build only one wing at a time, so I'll take the right wing to near completion, then begin on the left.
First I followed other builders and taped the gap between the spar flange and web so chips won't fall down in there never to be retrieved. I drilled all the nutplate attach holes #40 and countersunk them. I did both top and bottom of the spar.
There are many different ways to properly countersink the holes the screws actually go through. I'm going to follow Van's current method and rivet on all the nutplates and use them as a guide with the #30 countersink bit. Doing it this way is simple, but many builders opt not to do this because you can't debur the back side of the hole. From talking to those that have done it, the hole becomes knife edge anyhow, so deburring only enlarges the hole.
I got pretty good with the countersink and getting it to not chatter. After reading a bunch on VAF and experimenting, I found that putting a small drop of air tool oil on the hole to be countersunk and running the drill slow produced great results. Some choose to chuck the micro-stop countersink cage in a battery drill, but I found that I could "tease" the trigger on my Sioux air drill appropriately to get great results.
2/28/2008 Tank Attach Countersinking - 2.5 hours
I went ahead and drilled / countersunk the rivet holes for the access plate attach points since I had the #40 countersink set up. Then I went to try countersinking for the #8 screws that hold the tank to the spar. I first tried the Van's method (in the instructions) where you first rivet the nut plate on and use it to center the pilot on the countersink. This didn't work so well for me.
I was able to countersink about half the holes on the bottom of the right spar. Hopefully I can finish this up tomorrow.
