- Joined
- Jul 13, 2011
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- 2,090
I've been wondering recently about chipping that occurs during sharpening, especially as one moves up in grit, and a few recent posts have discussed this phenomenon, too, including one of my own. I found this guy Tom Blodgett's blog today and went through the entire four years of posts. Most of it is related to straight razor honing or the edge pro system and thus not really all that interesting to me, at all, but there are a few very good posts about general sharpening that I found quite illuminating. One of them was this one. In it, he talks about his research into why tiny chipping occurs during sharpening, especially at higher grits.
Take a look at this image from that post:
He drew arrows to point to the evidence of a gouge from a previous grit directly above the chip, which is anecdotal evidence that the two are related... well, it's pretty damn good evidence. Above every chip is such a gouge. That means that, at some point in the grit pogression, a coarse grit cut pretty deep into the steel and weakened the edge right at the point of the gauge. As the sharpener moved up the grit progression, at some point "snap!" a chip formed because of the weakness of the metal at the point of impact on the apex and the lack of supporting metal around that gauge, which wasn't apparent until the finer grits revealed it, thus causing the chip.
It's the most sensible explanation I've read, so far. He doesn't discuss steels, angles, or heat treat, but he does speculate that "overhoning" lies at the root of the problem and suggests that "underhoning" is the solution. I would guess that a good grit progression and doing the work to completely eliminate coarse scratch patterns would help a lot in avoiding this type of chipping.
Cheers,
Mag
Take a look at this image from that post:
He drew arrows to point to the evidence of a gouge from a previous grit directly above the chip, which is anecdotal evidence that the two are related... well, it's pretty damn good evidence. Above every chip is such a gouge. That means that, at some point in the grit pogression, a coarse grit cut pretty deep into the steel and weakened the edge right at the point of the gauge. As the sharpener moved up the grit progression, at some point "snap!" a chip formed because of the weakness of the metal at the point of impact on the apex and the lack of supporting metal around that gauge, which wasn't apparent until the finer grits revealed it, thus causing the chip.
It's the most sensible explanation I've read, so far. He doesn't discuss steels, angles, or heat treat, but he does speculate that "overhoning" lies at the root of the problem and suggests that "underhoning" is the solution. I would guess that a good grit progression and doing the work to completely eliminate coarse scratch patterns would help a lot in avoiding this type of chipping.
Cheers,
Mag
