You could run it with a same thickness, short board butted against the stone. Then to work the curve of the blade, required a little lifting of the knife handle with a sweep. Yes, the angle it gave was rather steep, 19-20*. Still, they allow you a way to obtain a sharp blade. The device came with a rubber insert for the clamp to grip the blade. By using this on only one side during sharping this allowed about a 2* finer adjustment. So, now were putting a 17-18* angle on the blade and this is a decent angle for a general use blade.
DM