The CMT 551-079X Bi-Metal Plus Hole Saw delivers a 3-1/8 in. (79mm) cutting diameter with the durability and speed professional tradespeople demand. Built from 8% Cobalt bi-metal (BIM) construction, this hole saw is engineered to cut through stainless steel, steel, cast iron, aluminum, copper, brass, and plastics - providing up to 2x longer cutting life than standard hole saws. Whether you are drilling through structural steel on a job site or cutting clean holes in sheet metal, the 551-079X is designed to handle demanding materials with precision and efficiency.

Key Features

• 8% Cobalt Bi-Metal (BIM) Construction - The high-cobalt alloy teeth stay sharper longer under heat and friction, delivering 2x the cutting life of standard hole saws so you replace tooling less often and stay productive.
• 3-1/8 in. (79mm) Cutting Diameter - Sized for common conduit, pipe, and fixture knockout applications, giving you a precisely dimensioned hole without secondary finishing work.
• 45mm Cutting Depth - Provides ample depth capacity to cut through thick-walled steel sections, multiple stacked sheet layers, and deeper material profiles in a single pass.
• XTREME FAST Push and Lock System - Compatible with Push and Lock arbors for tool-free blade changes in under 3 seconds, reducing downtime between cuts when working with multiple hole sizes.
• Variable Pitch Teeth (4-6 TPI) with Alternate and Side-Set - The variable tooth geometry reduces vibration and chatter, produces cleaner cut edges, and prevents tooth stripping when transitioning between material thicknesses.
• Right-Hand (RH) Rotation - Standard RH rotation is compatible with cordless drills, corded drills, and drill presses, so the saw pairs directly with existing shop and field equipment without adapters.
• Hexagonal Shank - The hex shank locks securely in the arbor and resists slipping under the high torque loads generated when cutting hardened steel and cast iron.
• Broad Material Compatibility - Cuts stainless steel, carbon steel, cast iron, aluminum, copper, brass, and plastics from a single tool, reducing the need to stock multiple hole saws for different materials.

Why This Product

• If your work regularly involves stainless steel or hardened steel - materials that destroy standard bi-metal saws quickly - the 8% Cobalt BIM construction keeps the teeth cutting longer and reduces costly, frequent replacements.
• The 45mm cutting depth accommodates thick structural sections and layered materials that shallower hole saws cannot reach through in a single pass, making it practical for mechanical, electrical, and plumbing rough-in work.
• The Push and Lock arbor compatibility means you can swap between hole saw diameters in seconds without tools, a real advantage when a job requires multiple knockout sizes back to back.
• With a single saw handling stainless steel, cast iron, aluminum, copper, brass, and plastics, contractors and fabricators can simplify their tooling kit rather than carrying separate saws for each material type.

Specifications

• Manufacturer Part Number: 551-079X
• Brand: CMT Orange Tools
• Diameter: 3-1/8 in. (79mm)
• Cutting Depth: 45mm
• Blade Material: Bi-Metal (BIM) 8% Cobalt
• Tooth Pitch: Variable 4-6 TPI (alternate and side-set)
• Rotation: Right-Hand (RH)
• Shank: Hexagonal
• Compatible Arbors: 550-PH85 (11/32 in. hex) and 550-PH11 (7/16 in. hex) Push and Lock arbors
• System: XTREME FAST Push and Lock
• Country of Origin: Made in Italy

Approved Applications

• Hole cutting in steel and stainless steel
• Hole cutting in cast iron
• Hole cutting in aluminum and non-ferrous metals
• Hole cutting in copper and brass
• Hole cutting in plastics
• Use with cordless drills, corded drills, and drill presses