Step 1 - 4 - Countersinking the vasrious holes, you really have to read and read again to make sure you have the correct holes. Mark them 100 and 120 for the different countersink bits.
Step 5 - 7 counter sink the hinghe brackets
Step 8 - 10 counter sink the spar cap spacers and doublers. The difficukty here is that the pieces are very thin so when you press the drill down the carpet on the table can flex the part. I resolved it by taking a scrap piece board and drill a big hole in it. Algin the holes you counter sink above the hole int he board, this way the rest of the metal piece is supported and makes it easier to countersink.
I primed all the pieces. a long day of work but good fun.
