Grinding & Sharpening CPM S90V
Grind everything possible annealed with fresh premium ceramics replaced early; post-HT means feather pressure, constant dunks, machine finishes. Diamond/CBN stones are mandatory at the bench - conventional stones burnish around the carbides and produce fake-sharp edges. 18-20 dps plus a microbevel. Budget double M390's shop time.
S90V is the steel that teaches makers what vanadium carbide really means: nine percent of the bar is particles harder than most of your abrasives. Every hour the edge lasts in cardboard was pre-paid at the grinder and the bench. Here is how to pay efficiently.
On the 2×72
Premium ceramic belts, replaced early and often — S90V kills the cutting edge of a ceramic faster than any steel on this site, and a half-worn belt on this steel is a heat gun. Hog everything possible in the annealed state (profile, bevels to 80-90%, drilling — carbide bits live longer); after heat treat at 59-61 HRC, sharp 120-grit ceramics with feather pressure and constant dunking. Finishing: structured abrasives, low expectations, and acceptance that hand-sanding S90V is a hobby for people who hate themselves — machine-finish this steel.
At the Bench
Diamond or CBN, mandatory — not preferred, mandatory. Conventional stones burnish the matrix and leave the carbides standing proud: the edge feels sharp-ish and performs dull. A coarse-medium-fine diamond progression plus diamond-emulsion strop delivers the edge the spec sheet promised; angles 18-20 dps. Sell every S90V blade with the diamond conversation, or field the ‘won’t sharpen’ email later — the physics live in the sharpening guide and the microbevel guide (a microbevel is extra useful here: touch-ups without fighting the full bevel).
The Budget
Double the belts, double the bench time of M390 — which was already half again a normal stainless. Quote build hours accordingly; S90V flagships are priced like flagships for shop-floor reasons, not marketing ones.
Common Mistakes
Half-worn belts turning into heat guns. Hand-sanding ambitions. Conventional-stone sharpening that leaves carbides proud and edges fake-sharp. Selling the knife without the diamond-stone talk. Underquoting build hours.
Safety
Fresh coarse ceramics on feather passes still bite fast – grip and rest discipline. Thin S90V edges chip during aggressive grinding: eye protection matters doubly. Every dunk is cheaper than one blued edge on the most expensive grind of your month.