Carpentry Counterbore mortising Drill Bits

Technical Data

• Structure: Composite design with central pilot drill + square/rectangular chisel jacket
• Shank: 1/4″ (6.35mm) hex/quick-release or 1/2″ (12.7mm) for heavy-duty use
• Material: High-speed steel (HSS) or tungsten carbide-tipped, heat-treated to HRC 48-50
• Sizes: Square/rectangle openings: 6-20mm (1/4″-3/4″), common set includes 8/10/12/16mm
• Cutting depth: 30-90mm depending on model
• Design features:

• Central drill core (hardness ≥HRC60) creates guiding hole
• Square/rectangular outer chisel forms the mortise
• Chip evacuation channels (U-shaped) prevent clogging
• Depth limiter collar for precise control

Advantages:

• One-step operation: Drills pilot hole + creates square/rectangular mortise + counterbore in single pass
• Precision: Square holes with ±0.1mm accuracy, ideal for tight-fitting mortise-tenon joints
• Versatile: Works with mortise machines, drill presses, or electric hammers with adapter