Brief Description: Roll Bar - Drill 631C/D's to fuselage.
Image 1 show the sequence of drill bits I used to get the final ¼” holes. The 631C/D’s were pre drilled with #30, so that is where you start. Then a #12, followed by a 0.246, then final ream with ¼” reamer.
I actually have a combination bit, second from top, that is 0.246” with a #12 pilot. This bit worked great going from #30 to 0.246 with one bit.