I am about to choose the prop retaining screw circle diameter and begin on the drilling guide and prop hub.
Is there any reason I should stick to one of the standard sizes as per the chart in post # 47?
I'm thinking that the 35 diameter will suit my prop and counterbore size. If possible, I'll go for 6 x 6 mm screws if wall thickness allows (which I think it will). The retaining nut on the engine shaft required a 17 mm socket which is around 25 mm outside diameter. This determines to a large degree, the smallest circle size.
The prop has arrived and will suit a hub up to 52 mm diameter anyway.