05-01-2020, 09:58 AM
Just received an email from a customer with a question. He just finished sharpening a blade and then garnered these three measurements at three different points on the edge: 90, 180, 220. He was wondering if his test methodology might be flawed.
First of all - even if one were intentionally trying to screw up the measurements, it's doubtful that one could produce this disparity in readings on a well ground and thoroughly deburred edge. Now, please don't take this as a challenge Exchange members! As a rule though, the statement is accurate.
90 - 180 - 220 do bear the mark of a wire (or false) edge however. In the first case (90), the edge had just enough structural stability to sever the test media cleanly. In the latter two measurements (180, 220) it didn't and either dented or folded the wire edge over before severing the test media. There could be other edge problems that could manifest in this manner but I advised the customer to look for a wire edge first.
Wire edges do make me think though. Usually, once a wire edge is removed, there is no significant reduction in sharpness. In the case of our customer, and once the wire edge is removed, he should end up with an edge that measures around 90. This leads me to believe that the width of the wire edge is about the same at the top as it is at the base where it will be separated from the newly created and structurally improved edge apex. So the problem with wire edges is that they are just "too tall" for their own good. So how's that for pure conjecture on my part? My mind is a terrible burden. I visualize microscopic things in dinner plate size and then draw conclusions. Those visualizations are sometimes later proven correct and sometimes not. I never reveal my batting average - too embarrassing.
First of all - even if one were intentionally trying to screw up the measurements, it's doubtful that one could produce this disparity in readings on a well ground and thoroughly deburred edge. Now, please don't take this as a challenge Exchange members! As a rule though, the statement is accurate.
90 - 180 - 220 do bear the mark of a wire (or false) edge however. In the first case (90), the edge had just enough structural stability to sever the test media cleanly. In the latter two measurements (180, 220) it didn't and either dented or folded the wire edge over before severing the test media. There could be other edge problems that could manifest in this manner but I advised the customer to look for a wire edge first.
Wire edges do make me think though. Usually, once a wire edge is removed, there is no significant reduction in sharpness. In the case of our customer, and once the wire edge is removed, he should end up with an edge that measures around 90. This leads me to believe that the width of the wire edge is about the same at the top as it is at the base where it will be separated from the newly created and structurally improved edge apex. So the problem with wire edges is that they are just "too tall" for their own good. So how's that for pure conjecture on my part? My mind is a terrible burden. I visualize microscopic things in dinner plate size and then draw conclusions. Those visualizations are sometimes later proven correct and sometimes not. I never reveal my batting average - too embarrassing.