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Abrasives and belt grinding in a working knife shop

Abrasives

Grinding & Sharpening M390

M390 on the 2x72 and at the bench: fresh ceramic belts, light cool passes once hard, diamond or CBN stones, and a realistic consumables budget.

1 min readWritten by Rich LinvilleFree to read

M390 earns its benchmark status at the cutting board and collects the bill in the shop: its vanadium and chromium carbides resist your abrasives exactly the way they resist the cardboard. The work is entirely manageable with the right consumables — and slow punishment without them.

Plain utility knife with a dark wood handle on a stitched leather pad beside a clean wooden cutting board.

On the 2×72

Ceramic belts, full stop — fresh premium ceramics (36-60 grit) hog annealed M390 honestly, while worn belts and cheap aluminum-oxide skate, glaze and heat the bar for nothing. Grind the bulk annealed; post-heat-treat at 60-62 HRC, drop to light passes with sharp 120-220 ceramics and treat every pass as a heat event: this steel holds its temper well, but a thin edge blues as fast as any. Structured-abrasive finishing belts (Trizact class) polish it beautifully for the satin the premium market expects — the progression logic lives in the belt buyer’s guide.

Satin-finished unhandled knife blank lying beside a fine textured abrasive belt strip on a dark foam pad.

At the Bench

Diamond or CBN stones are the honest answer — conventional stones cut the matrix around M390’s carbides and stall past medium grits, which is where its ‘hard to sharpen’ reputation comes from. A 300/1000 diamond pair plus a strop with diamond emulsion covers the whole life of the edge; owners get that advice with the knife, per the sharpening guide. Edge angles: 17-20 per side suits its toughness class.

Two diamond plates in black holders beside a leather-faced wooden paddle strop on a scarred dark bench.

The Realistic Budget

Plan roughly half again the belts and bench time of a mid stainless like AEB-L — then price the knife accordingly. M390’s whole business case is that the customer pays for shop effort once and enjoys the edge for months.

Four abrasive belt loops hanging from a rail beside a pinned-hole knife blank resting in a padded tray on a worn bench.

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Put the reference to work

I machine the parts, hand-assemble, track and test Torus grinders in Sterling, Illinois. Most orders ship in seven to ten business days from time of order.

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  • Classic aluminum 2x72 grinder, side view with flat-platen tool arm and yellow Safety Rules label, on black with a purple glow

    Torus 2×72 Classic Aluminum Belt Grinder

    Prior-design aluminum chassis, 90-degree tilt and 1.5-inch tooling arms.

    Starts at$995View

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