Prop Drilling

PM'd you Chris - come round any time Saturday eve or Sunday.

1/4" is only 10 thousands of an inch more than 6.1 mm which is the hole size you would be likely to end up with using a badly sharpened 6.1 mm drill!

DavidTappin wrote: 1/4" is only 10 thousands of an inch more than 6.1 mm which is the hole size you would be likely to end up with using a badly sharpened 6.1 mm drill!

Ther are 40 thou in a mm so the diference between 6.0mm (nominal bolt size) and 6.35mm (1/4") is only 14 thou'!
I agree with Dave, go for 1/4" or even 6.5mm otherwise swelling wood or tiny discrepencies in the drill guide will cause sticking bolts and consequent stripped threads in the hub. I think I have drilled out my guides to 6.5mm anyway so no point in trying for better unless you use a huge mill/drill and a dividing-head.