Product Description
CMT Hinge Boring Bit 25 x 70mm Left-Hand Rotation is a long-series boring bit engineered for drilling precise flat-bottom hinge cup holes in cabinet panels and thicker door components. Built on a super-strength steel body with a tungsten carbide (HW) cutting head and a PTFE-coated spiral, this bit is the reliable choice for European-style concealed hinge installation on multi-spindle boring machines, CNC boring centers, and drill presses alike. Left-hand rotation makes it purpose-matched for left-hand spindle positions on panel processing equipment, ensuring clean, accurate results on every bore.
Key Features
- Tungsten Carbide (HW) Cutting Head - delivers long-lasting edge retention and consistent flat-bottom hole quality through repeated drilling in hardwood, softwood, chipboard, MDF, and plywood.
- PTFE-Coated Spiral Flutes (2 Flutes) - the orange or black P.T.F.E. coating resists pitch and adhesive buildup, reducing cleaning downtime and extending overall tool life in production environments.
- Negatively Ground Spurs (2 Spurs) - precision-ground spur geometry scores the workpiece perimeter cleanly before the carbide head removes material, producing tear-free bore walls and smooth flat bottoms essential for proper hinge cup seating.
- Precision Balanced Centre Point - the HW centre point self-locates accurately on boring machine coordinates, minimizing bit walk and keeping hinge cup placement consistent across high-volume panel runs.
- Parallel Shank with Driving Flat and Length Adjusting Screw (10 x 26mm) - the standardized shank seats securely in multi-spindle machine chucks and boring adapters while the adjusting screw allows fine depth setting without removing the bit.
- Left-Hand (LH) Rotation - purpose-designed for left-hand spindle positions on dual-row boring machines and CNC boring centers, so the cutting geometry engages the material correctly and produces the same clean results as the matching right-hand model on its respective side.
- 25mm Diameter - matches the standard European concealed hinge cup dimension, eliminating sizing guesswork and ensuring compatibility with 35mm European hinge hardware commonly used in cabinet door mounting.
- 70mm Total Length (Long Series) - the extended length accommodates thicker cabinet components where short-series bits cannot reach full bore depth without repositioning.
Why This Product
- Matched to European hinge installation requirements - the 25mm diameter and flat-bottom boring geometry are the exact specifications required for seating standard European concealed hinge cups, making this bit a direct-fit solution rather than a workaround.
- Built for left-hand spindle positions - on multi-row CNC boring centers and multi-spindle machines, left-hand and right-hand spindles require opposite-rotation bits. Using this LH bit in the correct spindle position ensures proper chip ejection, correct cutting engagement, and full tool life.
- Long-series length handles thicker panels - the 70mm overall length gives clearance for boring through thicker cabinet door stiles and components where a standard-length bit would bottom out in the chuck before reaching full depth.
- PTFE spiral coating reduces maintenance stops in production - in high-volume cabinet manufacturing, pitch and glue buildup on uncoated bits causes friction, heat, and premature dulling. The P.T.F.E. coating addresses this directly, keeping the bit running smoothly between sharpenings.
Specifications
- Manufacturer Part Number: 369.250.12
- Brand: CMT Orange Tools
- Diameter: 25mm
- Total Length: 70mm
- Shank: 10 x 26mm
- Rotation: Left-Hand (LH)
- Number of Spurs: 2
- Number of Teeth: 2
- Tooth Geometry: Negatively ground spurs
- Blade Material: HW (Tungsten Carbide)
- Product Type: Hinge Boring Bit
- Series: Hinge Boring Bit 70mm
Approved Applications
- Drilling flat-bottom hinge cup holes for European concealed hinge installation
- Cabinet door hinge cup boring in solid hardwood and softwood
- Hinge cup drilling in chipboard, MDF, and plywood cabinet components
- Left-hand spindle boring on multi-spindle CNC boring machines and boring centers
- Panel processing on CNC boring centers and panel processing centers
- Use with boring machine adapter or chuck, handheld drill, or drill press where parallel shank is accepted
Frequently Asked Questions
Why does this bit need to be left-hand rotation - can I use it in any spindle?
This bit is specifically ground for left-hand (LH) rotation, meaning the cutting edges are oriented to cut correctly only when the spindle turns counter-clockwise (when viewed from the tip). Using it in a right-hand spindle would cause the spurs and carbide edges to rub rather than cut, producing poor-quality holes and rapid tool damage. Always match the bit rotation to the spindle direction on your boring machine.
What hinge system is this bit designed to work with?
This bit is designed for boring the 25mm cup holes required by European-style concealed hinges - the type commonly used in frameless cabinet construction. The flat-bottom bore geometry created by the precision balanced centre point and negatively ground spurs provides the clean, consistent seat that concealed hinge cups require for flush, gap-free installation.
Why is the 70mm long-series length important - when do I need it?
The 70mm total length is necessary when boring hinge cup holes in thicker cabinet door stiles or components where a shorter bit cannot reach full depth without the chuck contacting the workpiece surface. It also provides the clearance required in multi-spindle machine setups where the chuck body sits farther from the panel face. If your application involves standard-thickness panels and shorter boring depth, a shorter series in the same 25mm diameter may be sufficient.
What materials can this hinge boring bit cut through effectively?
The tungsten carbide (HW) cutting head and negatively ground spur geometry are suited for boring in solid hardwood, softwood, chipboard, MDF, and plywood - the full range of sheet goods and solid materials commonly used in cabinet door and panel manufacturing. The PTFE-coated spiral flutes help manage resin and adhesive residue that can accumulate when boring in chipboard and MDF.
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