Hi Mike, at a pinch you could also measure the "stick out" length by comparing it with a ruler, but I'm not too sure where the fixed point you would measure from on an original "wishbone" sharpener.
At any rate, even if a new design is made, the principle is the same, whether you rub from side to side or across the stone.
Many years ago I made a facetting tool for a chap in our local lapidary club, and the wishbone type sharpener is of the same principle, except the tool and stone being facetted are stationary while the lap revolves, which leads on to having a revolving copper lap charged with diamond dust and applying the wishbone sharpener and drill the same way.
Having a power driven revolving lap would make sharpening small carbide drills so much easier, when there is no hand movement to control.
Ian.