Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Well, that certainly elucidates things for me.

In my own semi-intuitive by-guess-and-by-God way, I had arrived at 48DP as the magic number for a set of cutters (too lazy and unskilled to make my own, though I really should try it). Ain't it good to see one's own preconceptions confirmed?

Thank you.