I didn't follow William Wynne's plan
when it came time to bolt a prop hub
onto the crank.
I redrilled and tapped the odd size holes
to standard 3/8 fine thread.
I made my hub take standard 3/8 socket head
bolts. The hard part of this process was
to do the drilling and tapping accurately.
The guide that I made had several holes the
tap drill size, and the rest 3/8".
I used it to hold the drill straight.
Once the smaller size had been used, I
rotated the jig to the 3/8 so that it
would guide my tap.
I made the jig on my Dad's milling machine
with a rotary table.