01-08-2018, 10:33 AM
I don’t think there is a right or wrong here. Just different ideas on how to accomplish something. I believe the first impetus behind the test stand is to try a test if edge heating during sharpening changes the hardness of the edge. More of a hardness test than a direct edge retention test.
As long as pressure and maybe speed was standardized, simply dragging a blade across a drill bit or Rockwell test block seems like a very quick, simple and probably quite accurate test. It would more accurately mimic real-world use than a straight down static pressure test. But I don’t really understand either exactly what is being tested for. Strictly hardness? Edge retention? Flexural bending resistance? All three?
My first inclination is that, up to a point, harder steel will always have better edge retention than softer steel. How could it not? But I don’t see edge retention testing’s main purpose to determine if one blade is better than another, but rather to help determine what grinds, initial sharpness and blade geometry perform best in a specific environment.
Ideally, edge retention would be measured after a blade has been used for whatever it is going to be used for. That’s especially cool if indeed the blade has a single mission in life. But what for a general purpose blade? A blade that may live to open a can, cut a stick or some rope or open a box? For that you might as well just see how the blade performs cutting rope. I suspect that would provide amazingly appropriate results.
It looks to me that the test stand performs a compressive strength test. But, a knife edge may roll before being crushed, and that would throw flexural or bending data into the mix.
I have the feeling that the test stand is more of device looking for a mission, than a mission looking for a device. I’m pretty sure it will do something and spew forth some sort of data. The most useful application of that data may be yet to be determined.
As long as pressure and maybe speed was standardized, simply dragging a blade across a drill bit or Rockwell test block seems like a very quick, simple and probably quite accurate test. It would more accurately mimic real-world use than a straight down static pressure test. But I don’t really understand either exactly what is being tested for. Strictly hardness? Edge retention? Flexural bending resistance? All three?
My first inclination is that, up to a point, harder steel will always have better edge retention than softer steel. How could it not? But I don’t see edge retention testing’s main purpose to determine if one blade is better than another, but rather to help determine what grinds, initial sharpness and blade geometry perform best in a specific environment.
Ideally, edge retention would be measured after a blade has been used for whatever it is going to be used for. That’s especially cool if indeed the blade has a single mission in life. But what for a general purpose blade? A blade that may live to open a can, cut a stick or some rope or open a box? For that you might as well just see how the blade performs cutting rope. I suspect that would provide amazingly appropriate results.
It looks to me that the test stand performs a compressive strength test. But, a knife edge may roll before being crushed, and that would throw flexural or bending data into the mix.
I have the feeling that the test stand is more of device looking for a mission, than a mission looking for a device. I’m pretty sure it will do something and spew forth some sort of data. The most useful application of that data may be yet to be determined.