Those of you who are reprofiling the idler wheels whilst removing the machining marks may find the images below useful? Dated May 1943 I believe it shows details of a possible 650mm diameter interim design. The key issue, which I assume was present on both the 700mm (early) and the 600mm (late) designs, is the fact that the rims were welded to webs on a cast hub. This means that the webs would be pretty much squared off with very little rounding of the edges.
Alastair
