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- Sep 4, 2004
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Quick background stuff ... the Kershaw Junkyard Dog II (JYD2) is a medium-large liner lock folder designed by Tim Galyean, featuring a novel "flipper" opening system, grey G-10 scales, with a full flat ground 3.75" Sandvik 13C26 steel blade.
Since the JYD2 has been discussed quite a bit already in other threads on BFC, I thought I'd mostly look at edge retention of 13C26, a steel designed for use in razor blades, comparing it to a couple of more familiar blade steels at high levels of push cutting sharpness.
My test was to measure loss of push cutting sharpness, with sharpness being the distance in inches from point-of-hold on newsprint where the blade will push cut. Sisal rope was chosen as the test material, with the 13C26 JYD2 being compared to O-1 tool steel at about 61HRC (Frosts laminated blade Mora) and VG-10 at around 58-60HRC (Spyderco.)
Although the JYD2's factory edge was quite good, the blade was first reprofiled to 12 degrees/side, with a 17 deg/side microbevel added. This is the same geometry as the VG-10 blade, and close to the Mora's ~10 deg./side primary edge with 15 degree microbevel. Using only fine Crock Sticks for finishing, the 13C26 JYD2 easily takes an almost freakishly sharp edge, push cutting newsprint at 4.5"-4.6".
Below are pictures of the reprofiled blade. FYI the edge bevels are .050"-.055" wide, with a blade thickness of .020" behind the edge, measured 3/4 of an inch back from the tip:
On to the testing ... shortly into it, I found that significant differences in edge retention could be determined with only 30 cuts of the rope. The first round of testing found the O-1 blade retaining about 93% of its push cutting sharpness, the VG-10 about 88%. The 13C26 however would still push cut the newsprint at the same distance from point-of-hold as when freshly sharpened, 4.6"!
These tests were repeated several times, with the 13C26 blade averaging better than 98% edge retention (which I'm sure is beyond the level of accuracy of my method.) The O-1 and VG-10 blades showed average retention of about 94% and 86% respectively, over 30 cuts.
Looking at the edges under magnification, it seems clear what's going on. The 13C26 alloy, designed to have very high edge stability, looked perfect. Not even the faintest hint of microchipping, no impaction, no rolling; flawless. The O-1 blade showed just the slightest bit of microchipping, the VG-10 more still and the chips larger and deeper. So for retaining a very fine edge when working with materials that aren't terribly abrasive, 13C26 seems an outstanding choice, doing exactly what it's designed to do.
Informally ... carrying and using the JYD2 for a while now, the terrific edge holding found when testing on rope is no fluke. If you prefer a polished edge and very high level of sharpness like this, this steel won't disappoint. It's also worth mentioning that it's a delight to sharpen, it's still a bit hard to believe that the edge retention is so high, as it wasn't at all difficult to reprofile on an AO stone. The burr formed during reprofiling was miniscule, and there were no problems related to a wire edge at all ... it just takes a wicked-sharp edge, quick and easy.
Like everyone else it seems, I'm very impressed with this knife overall. Ergonomics are outstanding, and obviously a lot of thought went into the design. Even the clip plays a role in making the knife feel very good and very secure in hand. The action is smooth, and when I had it disassembled I was very impressed with the fit and finish both inside and out.
And with Sandvik 13C26 performing like this, IMO this is a great knife.
Since the JYD2 has been discussed quite a bit already in other threads on BFC, I thought I'd mostly look at edge retention of 13C26, a steel designed for use in razor blades, comparing it to a couple of more familiar blade steels at high levels of push cutting sharpness.
My test was to measure loss of push cutting sharpness, with sharpness being the distance in inches from point-of-hold on newsprint where the blade will push cut. Sisal rope was chosen as the test material, with the 13C26 JYD2 being compared to O-1 tool steel at about 61HRC (Frosts laminated blade Mora) and VG-10 at around 58-60HRC (Spyderco.)
Although the JYD2's factory edge was quite good, the blade was first reprofiled to 12 degrees/side, with a 17 deg/side microbevel added. This is the same geometry as the VG-10 blade, and close to the Mora's ~10 deg./side primary edge with 15 degree microbevel. Using only fine Crock Sticks for finishing, the 13C26 JYD2 easily takes an almost freakishly sharp edge, push cutting newsprint at 4.5"-4.6".
Below are pictures of the reprofiled blade. FYI the edge bevels are .050"-.055" wide, with a blade thickness of .020" behind the edge, measured 3/4 of an inch back from the tip:
On to the testing ... shortly into it, I found that significant differences in edge retention could be determined with only 30 cuts of the rope. The first round of testing found the O-1 blade retaining about 93% of its push cutting sharpness, the VG-10 about 88%. The 13C26 however would still push cut the newsprint at the same distance from point-of-hold as when freshly sharpened, 4.6"!
These tests were repeated several times, with the 13C26 blade averaging better than 98% edge retention (which I'm sure is beyond the level of accuracy of my method.) The O-1 and VG-10 blades showed average retention of about 94% and 86% respectively, over 30 cuts.
Looking at the edges under magnification, it seems clear what's going on. The 13C26 alloy, designed to have very high edge stability, looked perfect. Not even the faintest hint of microchipping, no impaction, no rolling; flawless. The O-1 blade showed just the slightest bit of microchipping, the VG-10 more still and the chips larger and deeper. So for retaining a very fine edge when working with materials that aren't terribly abrasive, 13C26 seems an outstanding choice, doing exactly what it's designed to do.
Informally ... carrying and using the JYD2 for a while now, the terrific edge holding found when testing on rope is no fluke. If you prefer a polished edge and very high level of sharpness like this, this steel won't disappoint. It's also worth mentioning that it's a delight to sharpen, it's still a bit hard to believe that the edge retention is so high, as it wasn't at all difficult to reprofile on an AO stone. The burr formed during reprofiling was miniscule, and there were no problems related to a wire edge at all ... it just takes a wicked-sharp edge, quick and easy.
Like everyone else it seems, I'm very impressed with this knife overall. Ergonomics are outstanding, and obviously a lot of thought went into the design. Even the clip plays a role in making the knife feel very good and very secure in hand. The action is smooth, and when I had it disassembled I was very impressed with the fit and finish both inside and out.
And with Sandvik 13C26 performing like this, IMO this is a great knife.
