Hand Tools Archive
I tried a couple of two step freehand step-up type methods, and the results were pretty much in favor of the flat bevel, but probably because chasing subsequent grits in the interest of the microscope (e.g., photo and edge perfect needed) chased the bevel up to or past the flat bevel.
This was the only result that turned out better than expected, but the reason is probably simple - the method takes one bevel above the grind, and it's very easy to control geometry.
I'm out of heart on this board, so I can't run any more follow-up tests (e.g., finishing this iron with the guide on the washita stone), but those are things people can do and post the results of. I think if the flat bevel is as good or better for planes, but there MANY cases with knives and chisels where a small convex bevel can bail you out. They center (to me, I learned to describe this by listening to cliff stamp) around dealing with steel that is tough enough everywhere except the edge. rounding the bevel a little bit without doing it to a considerable amount of steel preserves the geometry (important for good slicing with a knife - you want the thin bevel geometry), but protects the edge by moving the failure point elsewhere (further from the edge).
This is useful on chisels. Most people would call it a microbevel, but I like a tiny rounded bevel for that. IT doesn't threaten later sharpening sessions and doesn't solve a tip problem by modifying the entire bevel.
This stone is deceptively fine. There is something about washitas that make them really favorable at cutting for their fineness. I've also had probably 20 washitas and this is the second finest of them all, at least of the ones that cut well. The other one was in a barber box with a strop top box, and this one was used by a carver, so it's maybe more favorable than one would get with other washitas. I also never recondition the surface of a washita for no reason, so this one is settled in.
The last condition that makes one squint a little looking at this result is it's where the heart is transitioning to sap and I didn't weigh the shavings or take pictures (just had enough of that). If I'd have weighed the shavings for all of these, it might find that I took a bunch of thinner shavings in the middle of this. Rotating planes and weighing the shavings allowed me to make sure nothing was slipping under the radar.
All that said, a slightly rounded bevel is fine, but I did catch myself with these results trying to imitate the three bevel method and probably limiting clearance a little bit. Of course, the cycle time was half as much, so is it important that on those tests, I lost about 20% of the edge life? Probably not. I would be sharpening before there was a problem, anyway, and spending half as long freehanding.
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- One more wildcard- Washita and 1 micron-768 feet