Angle Setting Jigs

[David Cefai]

I am preparing to make a new set of angle setting jigs (as in attached photo) for my 6" bench grinder. The idea is that I grind to an angle and then hone a micro bevel.

I have only just realised that if I grind say, a 25 degree angle such that when I place the chisel (or whatever) on the oilstone so that the front and back of the concave grind are both touching the stone then the actual bevel angle is less than 25 degrees. The difference is 2 to 4 degrees depending on the angle and the thickness of the steel.

Consistency is probably more important that the actual numbers but I would appreciate people's opinion as to whether one should aim for the stated angle at the cutting edge or when the front and back of the bevel are both in contact with the stone.

Thanks for any input.