Drilling F-631A

[Flying Scotsman]

Anyone see any issue with pilot drilling the F-631A channels for the roll bar while it's not clamped down (per instructions), using #40, then clamping, inserting the upper and lower straps, drilling them to #40 and then enlarging to #30?

I keep reading about people clamping everything and then drilling the channel and strap together using 12" #40 bits, but that seems like a difficult approach to getting the holes going...seems it would be easier to do the #40 holes on the channels some other way (holding in a vise, etc.), then using those holes to match-drill the straps.

 

[Stevea]

I do not see any problem with your suggested drilling process. I don't like the idea of using a 12" #40 to punch through all at one time either......too much chance for the bit to wander (even if starting with a center punch mark), or the hole to be not square to the part surface.

Mine were done like this: Drill #40 pilot holes in the channel flanges. Open the pilot holes to 1/8" (or 31 - 32 .... something slightly undersized from the #30 final size). Clamp the channels to a flat surface, then clamp the straps in place. Drill though everything with a #30.

 

[Flying Scotsman]

I like that idea even better...could even matchdrill to #31 or #32, then ream to #30 (love reamers...make such preeeettty holes!).