John wrote:

With no clearance hole I cannot see how a screw can pull two pieces
together.

I agree

Imagine if you created a deliberate space and then drove a
screw through and tightened it - then the thread would be good in both
pieces and they would not pull together.

Which is exactly what happens.



Your idea of a long plain section
is a sound idea but in the meantime I think a clearance hole is the
answer.

I know that's the proper way to do it with convebntional screws but these
newer screws seem to have wider flights, which would lead to a wider
clearance hole which would then not support the narrower shank.

Anyway I was just asking, I'd probably have been better off tosh nailing.

AJH