[REPOST FROM All About Edges] Thank you gentlemen! I appreciate your time in answering our questions. I can promise that our questions are not just idle "wonderings". As we continue to test edges with our new test stand we develop questions and we fall back on our friends who know more than we do to help answer them. The test stand demonstrates a very clear and measurable relationship concerning the amount of force applied to the edge, the number of iterations of the applied force and the beginning sharpness level of the edge. Our testing of individual knives seems to generally follow a somewhat intuitive course as well. For example, we reported that our HRC50 1095 spring steel knife edge rolled almost twice that of our HRC56 Henkel edge. Makes sense. Or does it? We posted all the detail of this test over in the test stand thread. Our edge rolling element impinges on the edge at a 10 degree angle and moves linearly down the edge with only 150 grams of force applied. Why didn't the edge just "pop" back to, at or near, it's original position? Here's a few pictures of, not the same, but an identical duplicate of the spring steel edge we tested.
![[Image: attachment.php?thumbnail=529]](http://bessex.com/forum/attachment.php?thumbnail=529)
![[Image: attachment.php?thumbnail=530]](http://bessex.com/forum/attachment.php?thumbnail=530)
![[Image: attachment.php?thumbnail=531]](http://bessex.com/forum/attachment.php?thumbnail=531)
side view bent return to straight
It certainly pops back in the pictures above. We're not so interested in why our 1095 spring steel didn't pop back as to what degree this springy effect either does, or does not, have on edge rolling. At first blush, not much. Our interest is heightened by Mark's references to the "toughness" of steels. It would seem that this toughness could be equated, on some level, with "springiness" so it could be explained then why a knife steel edge that was hardened to HRC65 and tempered to HRC56 might seem to roll less than a HRC61 edge (because the HRC61 edge isn't as tough). We're crossing bridges here before we come to them but wait, maybe we're not. We just tested a "Japanese" knife that was made in China. Supposedly HRC60-62 and did show some indications of being a harder knife according to its sharpening characteristics (and price). The edge rolled slightly more than the Henkel 55-57 knife. Lots of really interesting stuff to be figured out here.
side view bent return to straight
It certainly pops back in the pictures above. We're not so interested in why our 1095 spring steel didn't pop back as to what degree this springy effect either does, or does not, have on edge rolling. At first blush, not much. Our interest is heightened by Mark's references to the "toughness" of steels. It would seem that this toughness could be equated, on some level, with "springiness" so it could be explained then why a knife steel edge that was hardened to HRC65 and tempered to HRC56 might seem to roll less than a HRC61 edge (because the HRC61 edge isn't as tough). We're crossing bridges here before we come to them but wait, maybe we're not. We just tested a "Japanese" knife that was made in China. Supposedly HRC60-62 and did show some indications of being a harder knife according to its sharpening characteristics (and price). The edge rolled slightly more than the Henkel 55-57 knife. Lots of really interesting stuff to be figured out here.