Re: Screw diameter and strenght relation
If you question is about the load back driving the screw, then yes, I think the larger screw would be somewhat more resistant to turning due to the lower thread angle.
Consider that a thread is an incline plane wrapped around a cylinder. So if you unwrap the incline plane you have a wedge, and I think the smaller angle would be more resistant to movement when a force is applied perpendicular to the wedge.
Is it enough difference to affect anything in the real world? I don't know.
Jim Dawson
Sandy, Oregon, USA