I had my two drill blocks trimmed, now was time to drill a guide hole. I decided to drill the aft spar in steps starting with a #30, then 3/16", then 1/4" and last a letter N drill. I will finish the hole with a .3100 reamer. I made sure my drill press table was at a right angle to the drill and clamped the block in place. I drilled the hole and deburred. I placed a drill in the hole and checked for square. I had already marked the hole location on the aft spar attachment bar and payed particular attention the the 5/8" center of hole to edge distance minimum as specified in DWG 38. I initially drilled the spar by hand to a depth of 1/16" to act as a guide for the drill block. I just placed a drill bit in the block and used the 1/16" deep hole to lign the block up. I clamped the drill block in place and pulled the drill bit out. Using a flash light I was able to determine if the hole was lined up with the block. I used cutting oil and drilled the first hole. The alignment was perfect. I repeated the process with the right wing and progressively moved up in drill bit size until I reached the final letter N drill size. I left a N drill bit in each hole to keep the alignment and also clamped the spar into position. MY .3100" reamer has not arrived yet, so I will have to wait and finish the job another day.
