Sheepdog Specs
Primary Blade Grind Angle: 3.75 Degrees Per Side
Edge Angle: 27 Degrees Inclusive
Blade Thickness: ~1/8"
Blade Length: 3.25"
Initial Sharpness: 149 BESS
Mule Specs
Primary Blade Grind Angle: 2.5 Degrees Per Side
Edge Angle: 32 Degrees Inclusive
Blade Thickness: ~1/8"
Blade Length: 3.5"
Initial Sharpness: 134 BESS
Angles were measured at midpoint of the blade and marked so that the BESS testing could be done at that same point.
Sharpening Method
Both knives were sharpened free-hand
Bevel Setting: Atoma 140 followed by Shapton Kuromaku 120
Coarse Scratch Removal: Shapton Kuromaku 2k
Final Apex Refinement: DMT 25 Micron/600 Mesh Credit Card Hone
Why use the coarser DMT after the Shapton Kuromaku 2k? For one thing, because I can control my sharpening with it better, but it's a small hone and I just wanted to use the Shapton 2k to get the coarse scratches out. Secondly, because the softer abrasives of the ceramic stones burnish more.than abrade on high vanadium steels, I wanted to be sure to leave an apex that wasn't fatigued by that. Plus I just prefer that coarseness in general.
Test Method
I used 8.5" wide flaps off of Chewy boxes. These are single ply corrugated cardboard about 1/8" thick. I made slicing cuts along the corrugations from heel to tip of the knife, along the entire 8.5" width, so that the cardboard was affecting the steel with draw/slice cuts.
I tested the edge on my BESS tester every 100 cuts. Now, my BESS tester is one of the early prototype models, so it works a little differently than the newer models.
A brief explanation if it's not obvious by looking at it: The blade is placed in a magnetic base, and a thread is held in the yoke over it. You then place the thread on the knife blade, and add weight to the white platen atop the spindle until the thread severs. Then you can observe the weight in grams that you had to add. The whole spindle, planten and yoke must be included in the weight taken, so you basically add 50 to the readout.
This early prototype had a lot of problems and has issues with consistency, so I have to take several readings and average them out with each measurement. Once enough data is collected, the inconsistencies or "noise" are clearer to see. But you will note that at some points lower BESS scores than the previous will happen because of this, but overall you can take a measurement of BESS points gained per cut to ensure the final results follow that trend and aren't aberrant readings.
Data
As you can see I stopped taking BESS readings for the Sheepdog after 500 cuts, and only took another measurement at 1000. The average on that reading was a lot lower than I expected, again because of the inconsistencies with this BESS tester, but definitely not outside the range of .025 BESS points gained per cut.
For example, for the Mule, starting at 134 and gaining .025 BESS per cut then 134+(1000*.25) = 384 BESS which is pretty close to the last measurement. Given that the Sheepdog should have been 149+(1000.24) = 399, and with the wide inconsistencies with this BESS tester (some of the readings in the last average were as low as 260 and some as high as 330) that's close enough to the expected range.
Other Perspectives and Usefulness of BESS Data
One thing that was nice about the 8.5" flaps is that it was well suited to making a slicing cut from heel to tip with these blades. However, it's also easy to conceptualize this data into more standard rates. For example, 1000 x 8.5" cuts equates to about 708 feet of cardboard cut in total. It's also easy to convert the BESS Per Cut rates into BESS Per Foot as well by doing 'BESS Per Cut / Cut Inches * 12'. So in this instance it would be about .353 BESS Per Ft. Assuming it holds linearly, then, we could estimate the BESS score after cutting 2000 feet per cardboard by doing 'Starting BESS + (Feet Cut * BESS Pet Feet)'.
So for example with a starting BESS of 149 and a BESS Per Foot of .353 you'd end up at 855 BESS after cutting 2000 feet of cardboard. Or you could estimate what the max amount of feet in cardboard you could cut per a BESS limit with the inverse: (BESS Limit - Starting BESS) / BESS Pet Foot. So suppose with a starting BESS of 149, and at .353 BESS Pet Foot we didn't want to exceed 500 BESS, then we would know we could cut (500−149)÷.353 = 994 Feet of cardboard.
I might go ahead and do some similar testing for my 15V Mule, but maybe not given the inconsistencies with this BESS tester. Plus since there's already a lot of data out there about how much more edge retention 15V should have, I can probably reasonably extrapolate what the expected BESS Per Feet figure would be by looking at the TCC percentage differences between 10V and 15V in Larrin's data. For example 10V ranges from 725-to 800 TCC in Larrin's CATRA tests, and 15V is about 875 TCC so with 10V having basically 83-91% of 15V's score, I would estimate a theoretical BESS Per Foot score of 15V at .292-.323. Given the margin of inconsistency in the BESS scores it would be hard to tell the difference between data that confirmed that and the "noise" mentioned earlier, but applying the same formula I would expect 15V to cut through 1,086 to 1,202 feet of cardboard before reaching a BESS score of 500.
Conclusion
So given that the Sheepdog is 5 degrees more acute than the Mule, but is probably a lot softer, the numbers being pretty neck-to-neck like this makes sense.
In any case, I figured this might be interesting to some, and could possibly provide BESS data for others to compare with.
