09-03-2017, 11:52 PM
Steve,
Following your theory, (using the Tormek bevel angle and edge angle terminology):
Your plane blade has a single bevel, with a bevel angle of 25°. With only one bevel, the bevel angle equals the edge angle. With your knife, each of your bevel angles equals 20°. With two bevel angles, the edge angle of your knife equals 40º.
I think your BESS tester is testing the edge angle, without caring whether the edge angle is from a single or double bevel angles. Since 40º is > 25°, my common sense science thinks the higher BESS reading with the 40º than the more acute 25° edge angle is logical.
Following that logic, I would expect a knife with two bevel angles of 15° each (edge angle 30°) to read lower BESS than the same knife with double bevels, each ground 20º (edge angle 40°).
I would also expect a high carbon plane blade with a single bevel (and thus) edge angle of 25° to give a lower BESS reading than a premium plane blade of A2 steel ground to a bevel (and edge) angle of 30º. Granted, I would expect both the 40º edge angle knife and the 30º A2 plane blade to retain their sharpness longer.
Ken
Following your theory, (using the Tormek bevel angle and edge angle terminology):
Your plane blade has a single bevel, with a bevel angle of 25°. With only one bevel, the bevel angle equals the edge angle. With your knife, each of your bevel angles equals 20°. With two bevel angles, the edge angle of your knife equals 40º.
I think your BESS tester is testing the edge angle, without caring whether the edge angle is from a single or double bevel angles. Since 40º is > 25°, my common sense science thinks the higher BESS reading with the 40º than the more acute 25° edge angle is logical.
Following that logic, I would expect a knife with two bevel angles of 15° each (edge angle 30°) to read lower BESS than the same knife with double bevels, each ground 20º (edge angle 40°).
I would also expect a high carbon plane blade with a single bevel (and thus) edge angle of 25° to give a lower BESS reading than a premium plane blade of A2 steel ground to a bevel (and edge) angle of 30º. Granted, I would expect both the 40º edge angle knife and the 30º A2 plane blade to retain their sharpness longer.
Ken