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Knife dulls overnight after sharpening
#1
This is the knife:
 
https://www.amazon.com/Victorinox-Fibrox...B000QCLEFC
 
I ground it at about 15° (dps) on my Kally with a 150 grit Cubitron belt.  The 150 Cubitron is my go to belt for general use knife sharpening.  It is very fast, and especially considering I use a light touch when sharpening they seem to last a very, very long time.  I've been using the same belt for a long time now and it seems like new.  Pretty amazing.  Additionally, the 150 grit produces just the toothy edge I’m looking for.
 
I ground on alternate sides until I noticed a barely visible burr forming on one side of the blade.  I continued grinding on the opposite side as the burr until the very small, barely visible with careful examination under a good light burr formed evenly along the entire length of the blade.  Then I ground the other side in the same manner. 
 
My new method of deburring is to use a very fine Scotch-Brite belt.  It is by far the quickest method I’ve ever found, and does a most excellently complete job of removing burr without smoothing the toothy edge.
 
To deburr, alternating sides I did four passes each side with the S-B belt.  I could still see some little flecks of burr, so I ran my fingernail at 45° down each side of the edge and the burr sprinkled off the edge like tinsel rain.
 
Then I did one swipe on each side of the blade with the rough side of a clean leather belt on the Kally, wiped the blade a few times on my jeans against the top of my thigh to clean off any loose crud and took four sharpness reading from handle to tip:
 
110, 130, 110, 125
 
Now here is the interesting part.  I put the knife in one of those flat in-drawer knife blocks overnight.  The knife was not used it just sat in the drawer overnight.  The next day, today, I removed it and checked the sharpness.  The readings were:
 
160, 150, 150, 175
 
That’s a maximum 50 point reduction in sharpness from just sitting in a drawer overnight.  Without real proof, I suspect this sharpness reduction is due to a lesser extent oxidation but mostly from metal memory as the extremely thin toothy edge returned to whatever position it was in after the tortuous micro heating, tearing at the steel and bending that happened during grinding.
 
So, I did one pass each side of the blade using the rough side of the leather belt on the Kally, wiped it clean on my jeans and took four readings from handle to tip:
 
125, 110, 105, 100

Here is a picture of the edge:

   

 My best guess is that the one swipe on each side of the blade with the leather belt straightened the edge.
 
You may be thinking this is just a fluke.  Well, consider this:
 
The same day I sharpened the Victorinox I sharpened an 8” Calphalon chef’s knife.  It’s a nothing special, big, heavy blade with a full tang that is 1/8” wide at the spine and tapers to the edge.
https://www.kmart.com/calphalon-classic-...860553000P
 
Unfortunately I didn’t write down all the numbers documenting the saga but I did when I had finished sharpening and pretty accurately remember the rest.  I also noted the final sharpness numbers after checking it today.  So the first and final numbers are completely accurate.
 
I sharpened it using the same method as the Victorinox.  After sharpening the readings were:
 
95, 85, 115, 105
 
After sitting in the drawer next to the Victorinox overnight, the reading were all between
 
125 – 185
 
That’s up to a 100 point lower sharpness reading!  So today, as on the Victorinox, I did one swipe each side with the leather belt on the Kally and the readings were:
 
110, 130, 110, 125
 
So…, Hey Kids!  Try this at home!  Get a blade as sharp as you can, take four sharpness readings along the edge from handle to tip and let it sit for 24 hours or so.  The next day do another four sharpness readings.  Let us know your results!
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Knife dulls overnight after sharpening - by grepper - 08-10-2018, 09:40 PM

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