I finished drilling all of the pilot holes on the spar up to #21 size drill. This will work for all of the rivets. I will leave the final up-drilling for the tight-hole screws/bolts for later. I tried out some drill stops I bought to try to keep from marring up the spar too badly. They seemed to work OK. I dis-assembled all of the spar peices. Now I need to deburr everything and then do all of the countersinking before the pieces go back together. Onward!
All holes finally updrilled to #21 size.
Drill stops I used to keep from marking up the spar caps.
