CMT Hinge Boring Bit 35 x 57.5mm Left-Hand (LH) by CMT is a precision-engineered boring bit designed for drilling flat-bottom hinge cup holes required for European-style concealed hinge installation in cabinet doors and face frames. Featuring a tungsten carbide (HW) cutting head, 2 precision-ground cutting edges, and 2 negatively ground spurs, this left-hand rotation bit produces clean, accurate holes in a wide range of panel materials. The parallel shank with driving flat and length adjusting screw makes it compatible with boring machines equipped with adaptors or chucks, as well as multi-spindle setups used in cabinetry production.

Key Features

• HW (Tungsten Carbide) Cutting Head with Precision Balanced Centre Point - delivers accurate, centered entry on each bore, reducing tearout and ensuring repeatable hole placement across production runs.
• 2 HW Precision-Ground Cutting Edges (Z2) - dual carbide-tipped cutting edges maintain sharpness longer than standard steel bits, producing consistently clean flat-bottom holes needed for proper concealed hinge seating.
• 2 Negatively Ground Spurs (V2) - the negatively ground spur geometry scores the material boundary cleanly before the cutters advance, resulting in crisp bore walls free from chip-out, even in veneered or laminated panels.
• PTFE Coating on the Cutter Portion - the orange or black P.T.F.E. coating reduces friction and resists pitch and resin buildup, keeping the bit running smoothly and extending tool life between sharpenings.
• Super-Strength Steel Body - the high-strength steel shank and body resist deflection and absorb the stresses of repeated boring cycles, adding durability in demanding production environments.
• Parallel Shank with Driving Flat and Length Adjusting Screw - the 10 x 26mm shank with driving flat locks securely in adaptors or chucks and allows precise depth setting, reducing setup time and ensuring consistent hole depth across a batch.
• Left-Hand (LH) Rotation - designed specifically for left-hand spindle positions on multi-spindle boring machines, making it the correct choice for LH boring stations without requiring machine modification.
• 35mm Boring Diameter - matches the industry-standard 35mm cup size required for European concealed hinges, eliminating guesswork and ensuring direct compatibility with standard hinge hardware.

Why This Product

• The 35mm flat-bottom bore geometry is specifically required for European concealed hinge installation - this bit is purpose-built for that application, so cabinet makers can drill production-ready hinge cups without adapting a general-purpose bit.
• The left-hand rotation designation makes this bit the correct fit for LH spindle positions on multi-spindle CNC boring machines and boring centers, ensuring proper engagement and clean cutting rather than rubbing or deflecting.
• The combination of negatively ground spurs and HW precision-ground cutting edges addresses a common production problem - chip-out and rough bore walls on chipboard, MDF, and veneered panels - delivering cleaner results that require less finishing work.
• The P.T.F.E. coating actively resists pitch and resin buildup during extended boring runs, meaning less frequent cleaning stops and more consistent performance across larger production batches.

Specifications

• Manufacturer Part Number: 317.350.12
• Brand: CMT Orange Tools
• Diameter: 35mm
• Total Length: 57.5mm
• Shank: 10 x 26mm
• Rotation: Left-Hand (LH)
• Number of Teeth: 2
• Number of Spurs: 2
• Spur Geometry: Negatively ground spurs
• Material: HW (Tungsten Carbide)
• Product Type: Hinge Boring Bit

Approved Applications

• Drilling flat-bottom hinge cup holes for European concealed hinge installation
• Cabinet door hinge cup boring
• Face frame hinge mounting preparation
• Use in boring machines equipped with adaptors or chucks