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Rectangular cobalt tool bit, silver-grey finish, 4 inches long

Cleveland

Cleveland Cobalt M42 Rectangular Tool Bit 856 3/8 x 3/4 in x 4 in

SKU CH-YXA3-NZ9NY

Cobalt M42 rectangular tool bit for lathe work, 3/8 by 3/4 inches by 4 inches overall, non-beveled for right- and left-hand use

  • Cobalt M42 steel resists wear in high-speed cuts
  • Rectangular blank suits right-hand and left-hand turning
  • Non-beveled edges allow immediate shaping to custom profiles
  • 4-inch length provides reach for deep boring operations
  • Brand Cleveland backs industrial-grade tool-bit consistency

Cobalt M42 Rectangular Tool Bit

The Cleveland Cobalt M42 rectangular tool bit is a lathe tool blank made from high-speed cobalt steel. It suits machinists and fabricators who need a durable blank for custom grinding of turning tools. The M42 grade provides high hot hardness and wear resistance for cutting tough alloys. It is not suited for users needing pre-ground geometry or indexable insert tooling.

3/8 x 3/4 in x 4 in Non-Beveled Blank

The blank measures 3/8 inch wide by 3/4 inch high with an overall length of 4 inches. Its rectangular cross-section and non-beveled profile give a clean starting point for grinding right-hand or left-hand tool shapes. The solid cobalt construction resists deformation under heavy cuts. Builders requiring pre-formed chipbreakers or specific relief angles must grind those features themselves.

Model 856 Cobalt Grade Benefits

The Cobalt M42 material (model 856) delivers superior red hardness compared to standard high-speed steel, extending edge life in high-heat applications. This allows consistent performance when machining stainless steels, titanium, or other abrasive materials. The blank arrives ready for immediate customization on a tool grinder. Shops needing coated inserts or replaceable tips will not find those features here.

How it compares

Measured against everything we stock in Bits, Hole Saws & Accessory Kits, at today’s prices. Recalculated every night.

Price $52.99
Pricier than about 69% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameCLEVELAND

Questions about this item

Does the Cobalt M42 grade 856 tool bit fit a standard 3/8 by 3/4 inch tool holder?

The blank measures 3/8 inch wide by 3/4 inch high so it matches holders cut for that exact cross-section.

What length should I allow for when mounting this 4 inch rectangular bit in my lathe?

Overall length is 4 inches; verify your tool post clamp travel can accommodate that full length before tightening.

Can I grind cutting geometry on both ends of this non-bevelled Cobalt M42 blank?

Yes the bit is right and left hand capable with no factory bevel so you can shape either end as needed.

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