Assembled the spar and root rib to the skin. Install and match drill the wd-605 control horn. Then installed the conterbalance arm sub assembly and cleco the entire structure together. Match drill all components. Used my squeezer yoke to determine which holes in the lower skin / spar rivets i could use solid rivets in. Drilled the solid rivets holes to #40 and pop rivets holes to #30. Disassembled the structure. De-burred all holes and edges of the skin and spar. Set up and began dimpling the skin.