u/Impossible-Orange607

Keep the knife at 180 angle a stone laying on a 15 degree incline plane. Then glue a 6 or 8mm Diameter Disc Bubble Spirit Level to the same size Neodymium Magnet. Keep the bubble level up close to the spine on the flat of the knife blank. Use your thumb to flip the bubble level over the spine when making alternating passes. Don’t use a large bubble level as the bubble bounces around too much.

A hinge at the base of the incline plane will allow any angle to be put on the primary bevel.

Diagram courtesy of

ImplimentLogical4130 who had a question:

Like this?

https://i.postimg.cc/LX4hXs6W/image.png

That's genius. Thank you!!!