Match drilled #30 the forward cabin frame channels to the upper and lower straps. On one side I used 1” square tubing topped with strips of 3/8” hardwood flooring to space the fore and aft channels (photo 1). I only had enough material for about 2/3 of one side, so had to drill in shifts. On the other side I was able to drill just as accurately just using a machinist square set to 1-1/2” to set the frame depth, and didn’t have didn’t have to disassemble part way through (photo 2). Opened up the holes in the aft half of the frame to #30. Drilled the forward F-631E join plate to the frame (photo 3).
1" Square Tubing and 3/8" Hardwood set channel spacing
