CMT 543.079.51 Mortising Chisel and Bit Set by CMT is a precision-engineered hollow chisel and bit combination sized at 5/16" - purpose-built for cutting clean, square mortise holes in solid wood. Designed for use with any standard drill press mortising attachment or dedicated mortising machine, this high-speed steel set makes traditional mortise-and-tenon joinery more accurate and repeatable. Whether you are crafting furniture, building door frames, or constructing window frames, having a reliable mortising chisel and bit in your shop means the difference between a tight, lasting joint and one that fails over time.

Key Features

• HSS (High-Speed Steel) Construction - high-speed steel holds a sharp cutting edge longer than standard steel, reducing the need for frequent resharpening during demanding mortising work in hardwood and softwood alike.
• 5/16" Chisel and Bit Diameter - the 5/16" cutting diameter produces a precise, narrow mortise slot that is ideal for traditional furniture joinery and frame construction where tight-fitting tenons are required.
• 3/4" Shank - the standard 3/4" shank seats securely in most drill press mortising attachments and benchtop or floor-standing mortising machines, providing a stable, chatter-free cutting setup.
• Right-Hand (RH) Rotation - designed for right-hand rotation to match the standard spindle direction of drill press mortising attachments, ensuring proper chip ejection and clean mortise walls in a single pass.
• Single-Tooth Bit Design - the 1-tooth bit works in combination with the surrounding hollow chisel to bore and square the mortise simultaneously, delivering a clean-walled square hole with one plunge.
• Broad Machine Compatibility - fits any standard drill press mortising attachment as well as benchtop and floor-standing dedicated mortising machines, making it a versatile addition to a wide range of shop setups.

Why This Product

• For woodworkers who rely on mortise-and-tenon joints for maximum structural strength, the HSS chisel and bit combination delivers consistent, square mortise walls in one pass - reducing cleanup time and improving joint accuracy.
• The 3/4" shank and right-hand rotation make this set a drop-in fit for the vast majority of drill press mortising attachments already in the shop, eliminating compatibility guesswork.
• The 5/16" diameter fills a specific and common mortise size used in furniture frames, door construction, and window frames - providing the right tool for joints where a smaller chisel is needed for precision work.
• Built from HSS material, this chisel and bit set is engineered to handle the repeated plunging demands of mortising work in both hardwoods and softwoods without rapid edge degradation.

Specifications

• Manufacturer Part Number: 543.079.51
• Diameter: 5/16"
• Shank: 3/4"
• Rotation: Right-Hand (RH)
• Material: HSS (High-Speed Steel)
• Number of Teeth: 1
• Brand: CMT Orange Tools

Approved Applications

• Cutting square mortise holes in solid wood
• Mortise-and-tenon joinery for furniture making
• Door frame and window frame construction
• Use with drill press mortising attachments
• Use with benchtop mortising machines
• Use with floor-standing mortising machines
• Woodworking in solid hardwood and softwood