AlOx and SiC vs. Vanadium Part 1: SPS-II 13,000 and Spyderco UF

The purpose of this video was to empirically test whether sharpening high carbide volume, high hardness steels on aluminium oxide abrasives--which are theoretically unable to abrade the vanadium carbides in the steel--results in an inferior initial sharpness, apex strength, or high-sharpness edge retention relative to sharpening those same steels on CBN or diamond abrasives.

The knife used in the test is a Spyderco Mule Team in Maxamet at ~68 HRC. For those who are unaware, Maxamet is possibly the single most extreme high hardness, high carbide volume steels currently available and its application in knife making remains in the experimental stage. As far as I am aware, the Spyderco Mule Team in Maxamet is the first production knife offered in this steel.

The knife has an edge bevel angle of ~15-16 degrees per side with no microbevel, and was previously polished up to a 13,000 grit finish with an aluminium oxide Sigma Power Select II waterstone, and then polished further with a Spyderco UF sintered alumina ceramic benchstone. These two stones represent what is essentially the worst case scenario for sharpening high hardness, high carbide volume steels as both use aluminium oxide abrasive (supposedly far to soft to abrade vanadium), at a very high grit (supposedly the effects of this problem get worse the finer the abrasive) and both have a supposedly extremely high risk of abrading the metal matrix around the vanadium carbides leaving them extremely weakly supported and highly prone to carbide tear out.

The test procedure, developed in discussion with proponents of this proposition, was to sharpen the knife to the test grit, test the initial sharpness, and then cut some pine to test the apex strength. I then went on to do a bunch of slicing cuts on cardboard to check the high sharpness edge retention under abrasive wear.