The Edge Joint

One of the new things I learned while writing The Perfect Edge was Harrelson Stanley’s edge jointing technique. We’re not talking about jointing boards for gluing, but jointing a cutting edge on the finest stone as a last or near-last step in sharpening.

"Even after removing the burr after sharpening with your finest grit stone, you can feel a slight “tooth” to the edge. This is normal, but not advantageous. A step I’ve added to my sharpening is to remove that tooth by running the blade on edge, lightly along the length of the stone. You’ll feel the difference instantly." -- Harrelson Stanley

2000x magnification* of an O1 edge sharpened and jointed with a Shapton 16000-grit stone

Harrelson describes the technique here and at the 1:00 mark in this animated video. It’s just a gentle swipe of the edge, held vertically on the finest stone to remove the “teeth” that remain from honing. Harrelson claims this technique strengthens the edge. I know it sounds counterproductive but the photo above is one of a blade that I honed this way and I think the smoothness of the edge tells the tale.  I didn’t get a micrograph of an un-jointed 16000-grit edge but compare to an 8000-grit edge without jointing and you’ll get the idea:

2000x magnification* of a blade sharpened with a Shapton 8000-grit stone

It’s an interesting bit of sharpening detail and nuance from someone who knows a lot about sharpening. Try it out and please report back on how it goes.

*SEM Photos from The Perfect Edge.

An aside for you tech-heads out there: When you see an image from a scanning electron microscope (SEM) it will inevitably include a scale of some sort. In these that I’ve included here you’ll notice a row of small dots above the type in the lower right corner. It says “20um” meaning the row of dots is 20 microns long. A micron is a millionth of a meter and is represented by the Greek letter mu which looks like a lower-case u with a leading descender (like this: µ, but your browser may not support it).  Some other SEM’s will include a horizontal I with the micron size above it. I’ve claimed 2000x magnification on these but that’s the magnification of the raw image when it was shot. The actual magnification will depend on how it is reproduced. So if you measure that row of dots as you see them and do the math you can calculate the actual perceived magnification.

About Ron Hock

Owner of HOCK TOOLS (.com) and author of "The Perfect Edge, the Ultimate Guide to Sharpening for Woodworkers"
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5 Responses to The Edge Joint

  1. George Beck says:

    I use this method. I noticed that even a devilish sharp blade would often leave the shaving in ribbons. Like tiny teeth cutting the shaving even when sharpened on a 30,000 grit stone. The edge jointing method eliminated this and I get even shavings. This is important because to the eye the tiny ridges left in the surface can not be seen, but after finishing(oil finish) these little lines can be seen. I now begin the sharpening process by “jointing” the edge. Yes this is dulling the blade but I am starting with a smooth straight edge and sharpen from there.

  2. W Mickley says:

    I think that finishing, the very last part of sharpening, is very important and is somewhat neglected. That said, I think Harrelson’s method of finishing is pretty crude. I watched the video and tried the method a few times. My results were that I had more planing resistance, could not get quite so fine a shaving, and was left with a cloudy surface compared to my own regular routine. Probably a practised hand could get slightly better results with this method than I did, but I don’t think you will see too many deliberately dulling the edge. I wouldn’t want to try to explain Harrelson’s method to the straight razor crowd.

    • Ron Hock says:

      How about employing edge-jointing as a next-to-last step? Maybe hit both sides of the edge after the jointing? Just a thought.

      • W Mickley says:

        Yes, I think that would be helpful. I tried it and got somewhat better results. I’m not sure just how much more honing is needed and probably the lighter the jointing stroke the better. I suspect that aggressive stones are somewhat more prone to leaving a ragged edge than tamer stones.
        I like a clean strop for finishing. It still gave a better edge this evening, but most guys do best with the method they are accustomed to.

  3. Tico Vogt says:

    I’m going to give it a whirl next time, though I use 3M micro abrasive papers now and not stones. Like Ron suggested, maybe employ the jointing move just prior to a final .5 micron honing.

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