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My Sharpening and knife related videos
#61
Maintenance post #2
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#62
I just sharpened these two knives, from the same maker, and same series.  One with 180 grit, deburred.  The other up to 800 grit, then deburred with compound on smooth leather.  Pretty interesting difference.





Brian.
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#63
Liked the video. Nicely done on those knives, too.
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#64
Great video Mr. Brian.  It plainly demonstrates how even a very sharp polished edge can have difficulty cutting when a toothy edge performs well.  In your case the polished edge was almost twice as sharp as the toothy edge but still the polished edge slid across the surface while the tiny "teeth" of the toothy edge grabbed on, broke the surface fibers and cut well.

I'm sure there are some uses, like sushi slicing, where a polished edge is better.  However, at least in my experience, for general purpose knives toothy seems to perform better and last longer than polished precisely because of the slicing ability of toothy edges that your video demonstrates.

I posted the following a while ago about my experiences comparing polished and toothy edges when slicing rotten tomatoes.  The results were very similar to what you demonstrated so well with the newspaper tube.

http://bessex.com/forum/showthread.php?t...75#pid4475
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#65
Here are two microscope images I took of edges I sharpened.  Obviously the top edge is highly polished and the lower edge is toothy.

   

Let's consider how these two edges might perform in Brian's newspaper tube test.  It doesn't take much imagination to think of how the polished edge might slide on the surface of the newspaper tube while the toothy edge could grab the surface and cut.

Brian's video empirically demonstrates this hypothesis.
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#66
That was a well constructed demonstration  Brian and the best I've seen, to date, regarding polished vs. toothy. The video speaks clearly all by itself so I won't try to opine further. 

Just a great job and done in a very simple and succinct fashion. Thank you Brian!
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#67
Here's a new toothy versus polished video.  





Brian.
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#68
Another great video Mr. Brian!

It clearly demonstrates that, for most general purpose knives like cutlery, toothy edges cut but a polished edge can just slide on the surface.  Anyone who has cut tomatoes has probably experienced how frustrating it is when the blade just slides on the skin.

Below are some microscope images I took of blades I sharpened.  It’s easy to see why a polished edge can slide on a surface while a toothy edge acts like a tiny saw blade and cuts.  

   
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#69
Brian, I have found that a nice toothy edge ground with a 150-180 grit belt holds up quite well to deburring with the rough side of a leather belt. I’ve been able to get into the leather pretty good and not sacrifice the toothy edge. 
 
I’m guessing that the higher sharpness number on the toothy blade may be the result of remaining burr.  I’ll bet that you could clean the edge up a bit more on the leather belt, get a lower sharpness number and not sacrifice the benefits of that toothy edge.  Try one pass each side by just tickling, barely touching the edge to the leather belt at 45º and then a pass or two at sharpening angle to make sure everything is nice and straight.  Might be fun to give it a try to see if it works and still keeps the toothy edge.  Just a guess.  Maybe you have already done that.
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#70
(01-14-2021, 05:06 PM)grepper Wrote: Another great video Mr. Brian!

It clearly demonstrates that, for most general purpose knives like cutlery, toothy edges cut but a polished edge can just slide on the surface.  Anyone who has cut tomatoes has probably experienced how frustrating it is when the blade just slides on the skin.

Below are some microscope images I took of blades I sharpened.  It’s easy to see why a polished edge can slide on a surface while a toothy edge acts like a tiny saw blade and cuts.  
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