12-06-2017, 11:59 PM
(This post was last modified: 12-08-2017, 04:42 AM by KnifeGrinders.)
Mark, spare my blushes please.
A priory I thought coarser grits give a thicker edge, and the purpose of working the edge through progressively finer grits is to thin the edge to make it sharper.
That turned out to be an errancy.
Since I turned my sharpening hobby into a business and number of knives I sharpen a month jumped from tens to hundreds, I desperately needed a sharpening protocol for effective volume sharpening.
Having studied through the Todd S SEM images at https://scienceofsharp.wordpress.com and his comments for the 3rd time, it dawned upon me that the edge often well below 0.1 micron is already there even after a 300 grit stone, for sure after grit #1000 - 0.1 micron is a DE safety razor edge as we know.
For the 300 grit it depends on other variables, but for the CBN/Diamond #1000 edge-leading invariably.
On #1000 stones the apex edge-leading is 0.5 micron, and edge-trailing 0.1 micron or less.
In knife sharpening we raise an even burr all along the edge to make sure that the sides of the edge have met at the apex, and now I know that the edge apex is sharp right at the burr base.
Our desired sharpness is already there, we only have to deburr completely without rounding the very apex, and expose that 0.1 micron edge that already is there.
Sharpening knives is all about deburring.
If having deburred we get an edge duller than 50 BESS, it means we've rounded the edge and worsened the initial sharpness hidden behind the burr.
As this became clear, the very first trial of honing off the burr at -0.1 degree less than the edge angle to spare the very apex, gave 50 BESS i.e 0.1 micron DE razor edge, and proved the concept.
The rest is history.
Explanation to why the burrs may be so malleable is in that thickness of the burr is reduced to a few tenth of μm at the edge apex, and this band of foil between the edge and the burr is strong to flopping with some steel. SEM images show that while edge-leading grinding produces 0.1 micron apex, the edge-trailing - well below that; therefore burrs produced edge-trailing are more malleable and difficult to get rid of.
A priory I thought coarser grits give a thicker edge, and the purpose of working the edge through progressively finer grits is to thin the edge to make it sharper.
That turned out to be an errancy.
Since I turned my sharpening hobby into a business and number of knives I sharpen a month jumped from tens to hundreds, I desperately needed a sharpening protocol for effective volume sharpening.
Having studied through the Todd S SEM images at https://scienceofsharp.wordpress.com and his comments for the 3rd time, it dawned upon me that the edge often well below 0.1 micron is already there even after a 300 grit stone, for sure after grit #1000 - 0.1 micron is a DE safety razor edge as we know.
For the 300 grit it depends on other variables, but for the CBN/Diamond #1000 edge-leading invariably.
On #1000 stones the apex edge-leading is 0.5 micron, and edge-trailing 0.1 micron or less.
In knife sharpening we raise an even burr all along the edge to make sure that the sides of the edge have met at the apex, and now I know that the edge apex is sharp right at the burr base.
Our desired sharpness is already there, we only have to deburr completely without rounding the very apex, and expose that 0.1 micron edge that already is there.
Sharpening knives is all about deburring.
If having deburred we get an edge duller than 50 BESS, it means we've rounded the edge and worsened the initial sharpness hidden behind the burr.
As this became clear, the very first trial of honing off the burr at -0.1 degree less than the edge angle to spare the very apex, gave 50 BESS i.e 0.1 micron DE razor edge, and proved the concept.
The rest is history.
Explanation to why the burrs may be so malleable is in that thickness of the burr is reduced to a few tenth of μm at the edge apex, and this band of foil between the edge and the burr is strong to flopping with some steel. SEM images show that while edge-leading grinding produces 0.1 micron apex, the edge-trailing - well below that; therefore burrs produced edge-trailing are more malleable and difficult to get rid of.
http://knifeGrinders.com.au