The "bottom" face can now also be trued up, so that marking up can begin
A pentagon is drawn on the "bottom" face and the lines extended to the "top" face
On the "top" face, a small pentagon is also drawn. Five turning centres are drilled
Most of the bottom face is turned away to make a small spigot
An offsetting "trunnion" is made, which will fit on the bottom spigot
The recess in the trunnion is a tight fit over the spigot