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- Oct 18, 2001
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Read this thread for the full story first:
http://www.bladeforums.com/forums/showthread.php?t=302550
One thing that Bill and I talked about was the convex edge.
Bill Moran has been making convex-edged knives since day 1. That was one of the big reasons I started out the same way. The many conversations I had with Yvsa factored in as well.
The way Bill tells it, he figures that the convex edge was the ole standby edge, common on most every knife, until factories began mass-producing knives.
If you ask Cliff Stamp - a convex grind is easy to do; a flat grind, more specialized.
If you ask Bill Moran - a flat grind is easy to put on; a convex grind, more demanding.
He clarifies this as meaning that there are 100+ ways to put on a convex grind and the knife can be custom-tailored to the specific duty it is intended to perform.
A flat ground knife is made by putting a knife in a template (or holding it steady) and grinding away, keeping both sides equal. This is a task that is best done by a machine. The custom knifemaker is, in his attempt to recreate a flat grind, trying to replicate something a machine may do better.
The convex grind is more flexible, requiring more thought and anticipation (in terms of thickness and length).... a task that is more tailored to a custom knifemaker's modis operandi.
Another thing he mentioned is that many knife sharpness tests (such as rope slicing, push cut testing, etc.) are performed at 90 degrees to the material being cut. This is indeed a good test, but not a complete one. Frequently, a knife will be required to cut at a sharper angle. If you have your knife sharpened at a 25 degree angle (20-25 degrees being typical for a micro-bevel - EdgePro, Lansky, Sharpmaker, etc.), you are limited as to what angle you can approach the material.
A convex bevel, by nature of being a smooth uninterrupted arc, can be made to approach a material at almost any angle and still "grab". Only a chisel can grab near 90 degrees, but the convex edge can get much closer than ~65.
This may be yet another reason why convex edges are preferred in many woodcutting/woodcarving applications.
Keep this in mind:
None of this is "scientific research". Personally, I think flat grinds and micro-bevels lend themselves better to scientific analysis simply because exact angles can be readily determined, studied and compared.
Because of all the variables associated with the convex edge, it blurs the line between science and art. It is truly a case-by-case study where each piece is studied individually. Broad sweeping conclusions can only apply to convex edges in general, as each will vary not only by the maker, but from knife-to-knife. Even Bill Moran admits that each of his edges is different from the others.
What does all of this mean to me?
There is still much to be learned...much to be tested...in terms of the convex edge. I think the jury will always remain hung on this one....but knowing this only makes me hunger for it more.
http://www.bladeforums.com/forums/showthread.php?t=302550
One thing that Bill and I talked about was the convex edge.
Bill Moran has been making convex-edged knives since day 1. That was one of the big reasons I started out the same way. The many conversations I had with Yvsa factored in as well.
The way Bill tells it, he figures that the convex edge was the ole standby edge, common on most every knife, until factories began mass-producing knives.
If you ask Cliff Stamp - a convex grind is easy to do; a flat grind, more specialized.
If you ask Bill Moran - a flat grind is easy to put on; a convex grind, more demanding.
He clarifies this as meaning that there are 100+ ways to put on a convex grind and the knife can be custom-tailored to the specific duty it is intended to perform.
A flat ground knife is made by putting a knife in a template (or holding it steady) and grinding away, keeping both sides equal. This is a task that is best done by a machine. The custom knifemaker is, in his attempt to recreate a flat grind, trying to replicate something a machine may do better.
The convex grind is more flexible, requiring more thought and anticipation (in terms of thickness and length).... a task that is more tailored to a custom knifemaker's modis operandi.
Another thing he mentioned is that many knife sharpness tests (such as rope slicing, push cut testing, etc.) are performed at 90 degrees to the material being cut. This is indeed a good test, but not a complete one. Frequently, a knife will be required to cut at a sharper angle. If you have your knife sharpened at a 25 degree angle (20-25 degrees being typical for a micro-bevel - EdgePro, Lansky, Sharpmaker, etc.), you are limited as to what angle you can approach the material.
A convex bevel, by nature of being a smooth uninterrupted arc, can be made to approach a material at almost any angle and still "grab". Only a chisel can grab near 90 degrees, but the convex edge can get much closer than ~65.
This may be yet another reason why convex edges are preferred in many woodcutting/woodcarving applications.
Keep this in mind:
None of this is "scientific research". Personally, I think flat grinds and micro-bevels lend themselves better to scientific analysis simply because exact angles can be readily determined, studied and compared.
Because of all the variables associated with the convex edge, it blurs the line between science and art. It is truly a case-by-case study where each piece is studied individually. Broad sweeping conclusions can only apply to convex edges in general, as each will vary not only by the maker, but from knife-to-knife. Even Bill Moran admits that each of his edges is different from the others.
What does all of this mean to me?
There is still much to be learned...much to be tested...in terms of the convex edge. I think the jury will always remain hung on this one....but knowing this only makes me hunger for it more.