Fred Rowe
Well-Known Member
I find these mostly in production knives; blades that because of their secondary bevel grind cannot be made sharp. You can regrind the edge and put a new secondary bevel on the blade but it can't be sharpened.
A couple of examples: one was a brand name folding knife with a 3" blade. It was a visually nice looking knife slick finish and all, a 100 dollar knife I figure. I use a sharpener that can be set at most any angle and I set an angle of 24 degrees in the sharpener, put magic marker along the edge and made a few passes in the sharpener. I changed angles several times as indicated by the missing marker along the edge. It became apparent in short order that something was not as it should be. On closer inspection of the bevel grind, which was a hollow grind, we found why the blade would not take an edge; the bevels had been ground with either too small a wheel or to high on the blade the end result was the blade edge was widening, getting thicker instead of coming to the desired point at the edge.
The second knife was being sharpened with my adjustable sharpener; the same process was used, marking the edge with marker and making a few passes. This was a smaller folder with a 2 1/2" blade. This one was flat ground. After a few passes through the carbides it was obvious something was wrong. It turned out there were two different angles used on the blade. It looked like one side was 11 degrees while the other side was about 15 degrees.
Looks can be deceiving; just because its pretty says nothing about whether the blade has sound geometry.
Do you have any similar stories?
A couple of examples: one was a brand name folding knife with a 3" blade. It was a visually nice looking knife slick finish and all, a 100 dollar knife I figure. I use a sharpener that can be set at most any angle and I set an angle of 24 degrees in the sharpener, put magic marker along the edge and made a few passes in the sharpener. I changed angles several times as indicated by the missing marker along the edge. It became apparent in short order that something was not as it should be. On closer inspection of the bevel grind, which was a hollow grind, we found why the blade would not take an edge; the bevels had been ground with either too small a wheel or to high on the blade the end result was the blade edge was widening, getting thicker instead of coming to the desired point at the edge.
The second knife was being sharpened with my adjustable sharpener; the same process was used, marking the edge with marker and making a few passes. This was a smaller folder with a 2 1/2" blade. This one was flat ground. After a few passes through the carbides it was obvious something was wrong. It turned out there were two different angles used on the blade. It looked like one side was 11 degrees while the other side was about 15 degrees.
Looks can be deceiving; just because its pretty says nothing about whether the blade has sound geometry.
Do you have any similar stories?