I purchased a #21 countersink bit at Sun-N-Fun. I needed this to countersink the C-725 forward strut brackets. Once this was done I tapped the brackets for the screws that will hold them to the skin and frame using a 10-32 tap. I then screwed the ball post to each bracket, installed the brackets on the frame, and then installed the frame on the fuselage. This was necessary in order to properly position the aft brackets and drill them to the canopy deck.
