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Re: How sharp knife do I need

Thu Oct 03, 2013 7:37 am

You know, now that I think about it could have clarified that a lot more, that was supposed to be angle. Not percentage of grind, although I haven't totally looking into 50/50 sharpening a single bevel knife, I'm sure it would pretty much just change the geometry pending your angles are consistent. I had a lot on my mind yesterday. :mrgreen:

Let's say you grind the right side of the knife at 17 degrees, but you were really shooting for 15. You get a burr then flip to the left side. You sharpen the left side at 15 degrees, and get a burr on that side. After you get a burr on both sides you reduce pressure. Now, you get back to the right side and you reduce pressure. When you reduce pressure your angle might change to 15 degrees instead of 17 like when you were using more pressure. When you do this you aren't even hitting the edge anymore, but you may not realize it because you aren't familiar enough with the sound or stone feedback of hitting the edge, whatever it may be. So, if you don't hit the edge on the right side, but then keep hitting the edge on the other side it will push the edge over. An edge at low grit will still cut like this however.

This is just an example of one scenario, I was just trying to illustrate one of the many problems people might encounter while sharpening.

Re: How sharp knife do I need

Thu Oct 03, 2013 8:27 am

Excellent bit of insight from Shaun there. As you progress with time and skill you begin to understand things that are happening during the sharpening process that you cannot necessarily see with your eyes.

Once you learn to actually FEEL and recognize the suction from the perfect bevel contact with the stone, it makes it MUCH easier to hold a constant angle, much easier, because if you deviate angles you will immediately feel LESS suction as the bevel contact lessens. My favorite technique is to SLOWLY raise the angle while moving the blade over the stone until you FEEL that bevel suction/contact. This technique also helps convex the bevel shoulders which eliminates the wedging effect as you slice through whatever you're cutting.

Developing this FEEL is what allows Murray Carter (in one of his latest youtube videos) to successfully sharpen a blade with a paper bag over his head.


Re: How sharp knife do I need

Thu Oct 03, 2013 3:25 pm

...successfully sharpen a blade with a paper bag over his head...

Huh. I should call my ex-girlfriend and put her to work on the sharpening bench.
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