Great food for thought Grepper and thank you very much for asking the questions. This thread seems to draw a large number of views but it seems that we are addressing a room full of crickets most of the time so your post is much appreciated. You hear plenty from us so perhaps someone else will join you in a conversation.
We're on a roll (pun intended) around here. Tell you the truth, this is very interesting stuff. Even more so once we saw the results of the test we're posting now.
We're back to the far side of the world again and this was our next test subject:
So $150.00 knives to $5.00 knives. We must have a dozen of these laying around here that we have used to conduct various tests but purchased two new ones today for the test. We used one and conducted two tests simultaneously on a single blade. This was accomplished by creating two different sharpness levels, immediately adjacent to each other, on the same edge. Out of the box the edge measured 286 and after deburring measured 168. We then separated the edge into two halves with tape over the edge.
We then sanded the edge apex, out to the point, until we had a sharpness level reading of 291 then removed the tape. So now from the tip to the midpoint we have an edge that measures 291 and from the midpoint to the handle 168. The idea is to roll across the intersection of the two sharpness levels thereby testing the effects of rolling on sections of edge that have two different initial sharpness levels. The comparison was almost startling.
After one set we took our edge tester measurements and, of course, we have to take two measurements at two different locations on the blade. Sounds confusing so how about this; one measurement at each of two different locations.
1 set (291 begin) now 380 (168 begin) now 592
168 to 592 after one set??? This was amazing! We had to take another reading at a slightly different edge location to confirm.
[EDIT 3/24 - Turned out the following day that there was a reason for this "amazing" number. Apparently the factory had left us with a very nice wire edge on their knife and this had a significant effect on the roll result. We sharpened the knife in-house and conducted the test again. The numbers from the section of the blade that we dulled and then conditioned are valid. The factory edge (168) numbers are not. The retest began at a sharpness of 164 and after 1 set finished at 435 which is much more in-line with other knife results. Big difference. Live and learn.]
We got 602 on our second measurement so the huge roll on the sharpest side of the blade was for real. Back to the SET for two more sets of edge rolling.
3 sets (291) 473 (168) 704
5 sets (291) 595 (168) 805
So both sections of the blade just continue to roll at a fair clip and we just weren't that interested in hanging around to see where they would stop. In this test it is abundantly clear that the sharper portion of edge rolled at a much greater magnitude. It would also appear that we've reach a quality point nadir where steel, hardness factors etc. begin to really weigh in. No real idea on hardness but if it was over HRC 53 we'd be quite surprised. If it was 50 we wouldn't be surprised either.
We're on a roll (pun intended) around here. Tell you the truth, this is very interesting stuff. Even more so once we saw the results of the test we're posting now.
We're back to the far side of the world again and this was our next test subject:
So $150.00 knives to $5.00 knives. We must have a dozen of these laying around here that we have used to conduct various tests but purchased two new ones today for the test. We used one and conducted two tests simultaneously on a single blade. This was accomplished by creating two different sharpness levels, immediately adjacent to each other, on the same edge. Out of the box the edge measured 286 and after deburring measured 168. We then separated the edge into two halves with tape over the edge.
We then sanded the edge apex, out to the point, until we had a sharpness level reading of 291 then removed the tape. So now from the tip to the midpoint we have an edge that measures 291 and from the midpoint to the handle 168. The idea is to roll across the intersection of the two sharpness levels thereby testing the effects of rolling on sections of edge that have two different initial sharpness levels. The comparison was almost startling.
After one set we took our edge tester measurements and, of course, we have to take two measurements at two different locations on the blade. Sounds confusing so how about this; one measurement at each of two different locations.
1 set (291 begin) now 380 (168 begin) now 592
168 to 592 after one set??? This was amazing! We had to take another reading at a slightly different edge location to confirm.
[EDIT 3/24 - Turned out the following day that there was a reason for this "amazing" number. Apparently the factory had left us with a very nice wire edge on their knife and this had a significant effect on the roll result. We sharpened the knife in-house and conducted the test again. The numbers from the section of the blade that we dulled and then conditioned are valid. The factory edge (168) numbers are not. The retest began at a sharpness of 164 and after 1 set finished at 435 which is much more in-line with other knife results. Big difference. Live and learn.]
We got 602 on our second measurement so the huge roll on the sharpest side of the blade was for real. Back to the SET for two more sets of edge rolling.
3 sets (291) 473 (168) 704
5 sets (291) 595 (168) 805
So both sections of the blade just continue to roll at a fair clip and we just weren't that interested in hanging around to see where they would stop. In this test it is abundantly clear that the sharper portion of edge rolled at a much greater magnitude. It would also appear that we've reach a quality point nadir where steel, hardness factors etc. begin to really weigh in. No real idea on hardness but if it was over HRC 53 we'd be quite surprised. If it was 50 we wouldn't be surprised either.