The Mustang needs to rev higher; so this is Johns .. er machine thing he's made up to copy prop blades, its like a 3D profiler. I should have taken some pics of it in the working position, the left hand blade is the one to be copied, they are both lined up and then the pointer thingy on the left hand side arm follows the contours of the blade while the right hand side arm has a high speed electric motor attached with a cutting bit in it and that sort of carves the blade to the required shape.
(Technical editor P.Reeves)