With the wings joined, I bolted them on at the rear and bound them with elastics, hopefully for the last time! You may recall that to tap for 1/4"-20 you need to start with a 13/64" hole. However, the wing tube inner diameter is closer to 1/4". I started by chucking a 15/64" brad point bit in my drill, inserting in the sleeve and running it in reverse to mark a centre point, seen in this photo.







With a centred mark, I switched to the 13/64" bit and bored through the new forward mount to create the wing bolt holes. Note the reduced centre section.







Next step was to chuck the 1/4"-20 tap in the drill and slowly tap the holes...







... followed by some CA for the threads.