Product Description
CMT Hinge Boring Bit 28 x 57.5mm Left-Hand Rotation by CMT is a precision-engineered tungsten carbide tipped boring bit designed for drilling flat-bottom hinge cup holes in cabinet doors and face frames. Built to the exacting standards required for European-style concealed hinge installation, this 28mm diameter bit delivers clean, accurate bores with minimal tearout - making it the right choice for cabinetmakers, furniture manufacturers, and woodworking shops running multi-spindle boring machines, CNC boring centers, or panel processing equipment. The left-hand (LH) rotation matches the dedicated spindle positions found on professional boring machinery, ensuring proper cutting action and a smooth, flat-bottomed hole every time.
Key Features
- Tungsten Carbide (HW) Cutting Head - the precision-ground carbide construction maintains a sharp, consistent edge through demanding production runs, reducing downtime for tool changes and delivering repeatable bore quality in hardwood, softwood, chipboard, MDF, and plywood.
- PTFE-Coated Cutter Portion (Orange or Black) - the polytetrafluoroethylene coating on the cutting body resists pitch and glue buildup, keeping the bit running freely and extending tool service life in high-volume panel processing environments.
- Precision-Balanced Centre Point - the carbide centre point registers accurately on the workpiece before the cutters engage, preventing walking or drift and ensuring the hinge cup hole is bored exactly on center for consistent hinge alignment across every door or panel.
- 2 Precision-Ground Cutting Edges (Z2) - dual carbide cutting edges produce a smooth, flat-bottomed bore that meets the geometry required by European concealed hinge hardware, eliminating secondary cleanup operations.
- 2 Negatively Ground Spurs (V2) - the negatively set spurs score the wood fibers cleanly at the perimeter of the bore before the main cutters remove material, producing clean bore walls and a crisp entry hole with minimal surface tearout.
- Parallel Shank with Driving Flat and Length Adjusting Screw - the 10 x 26mm parallel shank with driving flat locks securely in boring machine adaptors or chucks, and the length adjusting screw allows precise depth setting for consistent hinge cup depth across a production run.
- Left-Hand (LH) Rotation - engineered specifically for the left-hand spindle positions on multi-spindle boring machines, ensuring proper cutting geometry and preventing tool damage caused by mismatched rotation direction.
- Super-Strength Steel Body - the high-strength steel body resists flex and vibration during boring, maintaining dimensional accuracy and contributing to the long service life of the carbide head.
Why This Product
- Purpose-Built for European Concealed Hinge Applications - the flat-bottom bore geometry and 28mm diameter match the cup requirements of standard European concealed hinges, making this bit the correct tool for cabinet door production rather than a general-purpose drill that requires additional fitting or adjustment.
- Matched Left-Hand Rotation for Multi-Spindle Boring Machines - boring machines with multiple spindles run left-hand and right-hand positions simultaneously. Using a bit with the correct LH rotation eliminates the risk of stripping threads, damaging the tool, or producing out-of-spec holes from a mismatched spindle direction.
- Carbide Tipped with PTFE Coating for Production Durability - the combination of a tungsten carbide cutting head and PTFE coating addresses two common failure modes - edge wear and resin buildup - in a single tool, reducing the frequency of interruptions during high-volume panel or cabinet production runs.
- Compatible with Adaptors or Chucks - the parallel shank design with driving flat makes this bit compatible with boring machines equipped with adaptors or chucks, broadening its usefulness across different machine configurations without requiring specialized toolholders.
Specifications
- Manufacturer Part Number: 317.280.12
- Brand: CMT Orange Tools
- Diameter: 28mm
- Total Length: 57.5mm
- Shank: 10 x 26mm
- Rotation: Left-Hand (LH)
- Number of Spurs: 2
- Number of Teeth: 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-style concealed hinge installation
- Cabinet door hinge cup boring
- Face frame hinge mounting preparation
- Panel processing on multi-spindle CNC boring machines and boring centers
- Use on boring machines equipped with adaptors or chucks
Frequently Asked Questions
What is the correct rotation direction for this bit, and why does it matter?
This bit is a left-hand (LH) rotation tool. Multi-spindle boring machines have dedicated left-hand and right-hand spindle positions, and using a bit with the correct rotation direction is essential for proper cutting action and to prevent damage to the tool or machine. Installing an LH bit on an RH spindle - or vice versa - will not cut correctly and can damage the toolholder or the workpiece.
What type of machines is this hinge boring bit compatible with?
This bit is designed for boring machines equipped with adaptors or chucks. The 10 x 26mm parallel shank with driving flat is the standard interface for these machine configurations, and the length adjusting screw allows precise depth setting to suit different machine setups.
Why are negatively ground spurs important for hinge cup drilling?
The 2 negatively ground spurs on this bit score the wood fibers cleanly around the perimeter of the bore before the main carbide cutting edges remove material. This produces clean bore walls and a crisp entry hole, which is especially important when drilling cabinet doors in hardwood or veneered panel materials where surface tearout would be visible or would affect hinge seating.
What does the PTFE coating on the cutter portion do?
The orange or black PTFE (polytetrafluoroethylene) coating applied to the cutter portion of the bit resists the buildup of pitch, glue, and wood resins during boring. In production environments where this bit is used continuously, the coating helps maintain smooth cutting action and extends the service intervals between cleanings or tool replacements.
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