01-05-2018, 03:23 AM
(This post was last modified: 01-05-2018, 05:54 PM by KnifeGrinders.)
The initial sharpness was almost the same.
@grepper: "Could this indicate the depth of the loss of hardness ..."
That's what I think as well, just the very edge apex gets softened. The difference evens as the apex in Knife Grinders’ knives (the reddish line) gets blunt by the 3rd hour.
Checking the edges at 1.5 hour, the overheated edge is rolled, while the KG's not.
These two curves tell us more than that, and what they tell is typical, as they are average numbers drawn from many knives over several days.
Good brand knives lose the initial sharpness within the first hour of use, and stay the same pretty sharp for the next 3-4 hours - as in the diagram above, hardness 56-58 HRC; while in the inferior brands (hardness <= 55 HRC) sharpness keeps worsening with time.
In other words, change in BESS scores with work hours helps differentiate better blade steel from inferior.
@Me2 "Where is their cutoff for what they consider dull?"
When they start feeling it dull, the edge often scores in the "very sharp" range on BESS.
Someone said that the edge retention also depends on how we cut.
I was amazed bedazed at how long the meat plant operators can maintain their knife sharp, they may have their knife shaving sharp for hours, having de-boned hundreds of legs and shoulders, cutting through tendons, not flesh.
Honestly, it's a mystique to us unsophisticated.
To be more correct, it's both art of cutting and art of steeling.
The best of them steel the edge very gently, like tongueing an oyster, one touch per side.
@grepper: "Could this indicate the depth of the loss of hardness ..."
That's what I think as well, just the very edge apex gets softened. The difference evens as the apex in Knife Grinders’ knives (the reddish line) gets blunt by the 3rd hour.
Checking the edges at 1.5 hour, the overheated edge is rolled, while the KG's not.
These two curves tell us more than that, and what they tell is typical, as they are average numbers drawn from many knives over several days.
Good brand knives lose the initial sharpness within the first hour of use, and stay the same pretty sharp for the next 3-4 hours - as in the diagram above, hardness 56-58 HRC; while in the inferior brands (hardness <= 55 HRC) sharpness keeps worsening with time.
In other words, change in BESS scores with work hours helps differentiate better blade steel from inferior.
@Me2 "Where is their cutoff for what they consider dull?"
When they start feeling it dull, the edge often scores in the "very sharp" range on BESS.
Someone said that the edge retention also depends on how we cut.
I was amazed bedazed at how long the meat plant operators can maintain their knife sharp, they may have their knife shaving sharp for hours, having de-boned hundreds of legs and shoulders, cutting through tendons, not flesh.
Honestly, it's a mystique to us unsophisticated.
To be more correct, it's both art of cutting and art of steeling.
The best of them steel the edge very gently, like tongueing an oyster, one touch per side.
http://knifeGrinders.com.au