Product Description
CMT 317.240.12 Hinge Boring Bit - 24mm x 57.5mm Left-Hand Rotation by CMT is a precision-engineered left-hand hinge boring bit designed for drilling flat-bottom hinge cup holes in cabinet doors, face frames, and panel components. Purpose-built for European-style concealed hinge installation, this 24mm diameter bit features a tungsten carbide (HW) cutting head with 2 precision-ground cutting edges and 2 negatively ground spurs that deliver clean bore walls and accurate flat-bottom results. 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 CNC setups where consistent depth and alignment are critical.
Key Features
- HW (Tungsten Carbide) Cutting Head with Precision Balanced Centre Point - the carbide-tipped construction stays sharp longer through hardwood, MDF, and chipboard, reducing replacement frequency and downtime during production runs.
- 2 Precision-Ground HW Cutting Edges (Z2) - dual cutting edges ensure balanced cutting forces and a consistently flat, smooth bore bottom, which is essential for proper seating of European concealed hinges.
- 2 Negatively Ground Spurs (V2) - negatively ground spurs score the perimeter of the hole before the cutters advance, producing clean, tear-out-free entry holes in veneered panels, plywood, and solid wood.
- PTFE-Coated Cutter Portion (Orange or Black Coating) - the P.T.F.E. coating on the cutter body resists pitch and resin buildup, keeping the bit running freely and extending service life in production environments.
- Super-Strength Steel Body - the steel body provides the structural rigidity needed to withstand the repetitive high-cycle demands of cabinet manufacturing and panel processing operations.
- Parallel Shank with Driving Flat and Length Adjusting Screw - the 10x26mm shank with driving flat and integrated length adjusting screw ensures secure tool retention and precise depth setting in adaptors or chucks, minimizing setup time and variation between bores.
- Left-Hand (LH) Rotation - engineered for left-hand rotation to pair correctly with left-hand spindle positions on multi-spindle boring machines, allowing accurate mirror-image hinge cup patterns without repositioning workpieces.
Why This Product
- The 24mm diameter and flat-bottom bore geometry match the industry-standard cup size required for European concealed hinges, making this bit a direct fit for cabinet door and face frame hinge installations without modification.
- Left-hand rotation is specifically required for left-side spindle positions on multi-spindle and CNC boring machines - using a right-hand bit in this position would produce incorrect chip ejection and poor surface finish, making the correct rotation critical to bore quality.
- The combination of negatively ground spurs and HW precision-ground cutting edges addresses two common failure points in panel boring - tear-out at the entry perimeter and rough bore bottoms - delivering cleaner results in veneered and laminated materials.
- The parallel shank with driving flat and length adjusting screw provides direct compatibility with boring machines equipped with adaptors or chucks, streamlining tool changes on production equipment without the need for specialized holders.
Specifications
- Manufacturer Part Number: 317.240.12
- Brand: CMT Orange Tools
- Diameter: 24mm
- Total Length: 57.5mm
- Shank: 10x26mm
- Rotation: LH (Left-Hand)
- Number of Spurs: 2
- Number of Teeth: 2
- Tooth Geometry: Negatively ground spurs
- Head Material: HW (Tungsten Carbide)
- Coating: P.T.F.E. (orange or black) on cutter portion
- 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
- Use on boring machines equipped with adaptors or chucks
- Compatible materials: solid hardwood, softwood, chipboard, MDF, plywood
Frequently Asked Questions
What rotation direction does this bit require - and why does it matter?
This bit is designed for left-hand (LH) rotation. On multi-spindle boring machines and CNC boring centers, spindle positions are designated as left-hand or right-hand based on their location in the machine layout. Using a left-hand bit on a left-hand spindle ensures proper cutting geometry, correct chip ejection, and a clean flat-bottom bore. Installing a right-hand bit in a left-hand spindle position would cause the cutting edges and spurs to scrape rather than cut, degrading bore quality and shortening tool life.
What type of machine is this hinge boring bit compatible with?
This bit is designed for boring machines equipped with adaptors or chucks. The parallel 10x26mm shank features a driving flat and a length adjusting screw that allow secure, depth-repeatable installation in these machine types. It is suited for multi-spindle CNC boring machines, CNC boring centers, and panel processing centers that accept this shank configuration.
Why are negatively ground spurs important for hinge cup boring?
Negatively ground spurs score the perimeter of the bore before the main cutting edges advance through the material. This pre-scoring action severs the surface fibers cleanly, which prevents tear-out at the hole entrance - particularly important when working with veneered panels, laminated chipboard, or plywood where surface quality directly affects the finished appearance of the cabinet door.
What does the P.T.F.E. coating on the cutter portion do?
The P.T.F.E. coating applied to the cutter portion of this bit acts as a non-stick surface barrier that resists pitch, resin, and glue buildup during boring operations. By preventing material adhesion on the cutting body, the coating helps maintain consistent cutting performance across extended production runs and reduces the frequency of cleaning or maintenance needed to keep the bit operating efficiently.
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