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Questions for Winston and Bill T on Unicorn Edge.

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Questions for Winston and Bill T on Unicorn Edge.

#1

Questions for Winston and Bill T on Unicorn Edge.

Barry Irby

Thank you Winston for posting the video on the Unicorn edge in Johanna's post on her dressers. Her dressers are coming along nicely and the mortises appear beautiful and well done, but I did not want to detract from her post with my questions.

My question is Have I accidentally achieved a Unicorn edge without knowing it? I have a Harbor Freight 1 X 30" strip sander and have gotten some 600, 800, and 1200 grit strips and a leather strop for it. I also got a little guide for it, but find it less than useful and don't use it. II have sharpened lots of knives and chisels and plane irons.

The leather strop appears to do what the buffing wheel is doing. I do not have a microscope so can not see it at that scale, but I am getting a slightly convex edge that is mirror polished.

I flatten the backs of the chisels and plane irons on glass with a variety or grits on film from 3-M, I believe. They start at 200 and go to something crazy like 50,000. (It's so fine you can't feel the difference between the strip and the glass.)

If I buff the back of the plane irons on the leather strop very carefully, I end up with a tiny back bevel. Similar I think to the one people are doing by using a thin steel ruler to elevate the iron.

If I polish the back of the chisel I do it before sharpening so the when the chisel is beveled and sharpened any convex surface at the edge is ground away.

I'm getting edges that will slice paper like butter. Once a knife is sharpened I can resharpen it in seconds.

I wish I could try one of your edges to see what it's like.

Am I There yet? Is there anything left to try? I think I have a buffing wheel, is there anything to be gained firing it up?

Re: Questions for Winston and Bill T on Unicorn Edge.

#2

Re: Questions for Winston and Bill T on Unicorn Ed

Bill Tindall, E.Tn.

The leather strop appears to do what the buffing wheel is doing.

Doubtful. Unicorning sharpens and strengthens without changing the overall profile of the bevel side of a chisel. I don't know why this point is not clearly understood from the video, maybe because people begin convinced they are already doing it and fail to note the details.

When Unicorning is successfully employed the result is a convex profile on the first few thousandths of the tool tip and no where else. Because the alteration is confined to this tiny amount the rest of the chisel performance remains unaltered.

If you are leather belting the whole bevel you are sharpening with a power strop. You are also altering the whole of the bevel profile for the worse.

Re: Questions for Winston and Bill T on Unicorn Edge.

#3

Re: Questions for Winston and Bill T on Unicorn Ed

Barry Irby

I am only stropping the very edge for a matter of 10 seconds or less. About the same time as he use the biffing wheel in the video.

I will try the buffing wheel next time I sharpen.

Re: Questions for Winston and Bill T on Unicorn Edge.

#4

Re: Questions for Winston and Bill T on Unicorn Ed

Bill Tindall, E.Tn.

I comes down to how much you are altering the bevel. David Weaver has found a power driven leather belt too aggressive for Unicorming but your results may differ. Roll the edge in good light and look for the glint across the tip. It should be only a few thousandths of an inch wide. If more it will be sharp. It may be strong. But penetration may suffer.

But the proof is in the pudding. Do some end grain chopping with your profile and if it holds up , with good penetration chopping, it is close enough .

The Unicorn profile is not how it is done, it is the result that counts.

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