Hand Tools Archive

Re: second unicorn edge retention test

David Weaver
..to get that much damage out of an edge. It's probably 3 thousandths or 4 thousandths deep in some spots.

The first time I unicorned the 28 degree chisel, I used it, there was no additional edge damage but strangely, some of the deep bits of prior damage was still there, and I had to redo that test. Bizarre to see a perfectly even defected edge!!

I thought that I'd done enough to hone it out, but wasn't correct. Which means if you encounter this edge damage and refresh your bevel and raise a large wire edge, you're still probably not getting it all out. It's better to avoid it.

When we were doing the plane iron testing and the sentiment was that the iron's behavior changes after damage, I'd imagine that in reality the damage hasn't all been removed because you can't see this tiny damage, and after honing, you can't feel it either. The microscope sees it pretty easily, though. It's unusual looking when it's there but the edge is straight.

For what it's worth, when I did the plane iron test, when the maple damaged the irons, once it was honed out completely as confirmed by the microscope, I didn't notice any difference in edge behavior.

The next test of interest will be to see if the sorby chisel can outrun a V11 chisel with a flat bevel if the sorby has the unicorn. Outrun means retain unicorn status (better edge retention and more ease through the material being chiseled).

I was already convinced that this is superior, but now after redoing this test and swapping chisels, I have no doubt I can demonstrate it over and over without favoring one method or another.

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