Product Description
CMT Hinge Boring Bit 35 x 70mm Left-Hand Rotation by CMT is a long-series carbide-tipped boring bit engineered for drilling precise flat-bottom hinge cup holes in cabinet doors and thicker panel components. Designed specifically for European-style concealed hinge installation, this 35mm diameter bit delivers clean, accurate bores in a wide range of wood-based materials. The left-hand rotation and extended 70mm overall length make it the right tool for deeper cup drilling applications where standard-length bits fall short.
Key Features
- Tungsten Carbide (HW) Cutting Head with Precision Balanced Centre Point - the carbide head maintains sharpness through demanding production runs, while the balanced centre point prevents walking and ensures the bore starts exactly on target for repeatable, accurate hinge cup placement.
- 2 Precision Ground Cutting Edges (Z2) with Negatively Ground Spurs - negatively set spurs shear the material fibers cleanly before the cutters remove waste, producing smooth bore walls and a flat bottom with no tearout - critical for consistent European hinge seating.
- 2 Spiral Flutes for Efficient Chip Evacuation - twin spiral flutes clear chips continuously during drilling, reducing heat buildup and preventing clogging when boring into chipboard, MDF, plywood, or solid wood.
- PTFE-Coated Spiral Portion - the orange or black P.T.F.E. coating on the spiral prevents pitch and glue buildup, extending tool life and keeping the bit cutting freely even in resin-rich or adhesive-coated sheet goods.
- Super-Strength Steel Body - the high-strength steel shank and body resist flex and vibration during high-cycle production boring, maintaining geometric accuracy cut after cut.
- Parallel Shank (10 x 26mm) with Driving Flat and Length Adjusting Screw - the parallel shank with driving flat locks securely in multi-spindle boring heads or chucks, while the length adjusting screw allows precise depth setting without trial-and-error re-clamping.
- Left-Hand (LH) Rotation - purpose-built for left-hand spindle positions on multi-spindle CNC boring machines and panel processing centers, ensuring proper cutting geometry and a clean bore when used in the correct spindle orientation.
Why This Product
- The 70mm total length gives this bit the reach needed for boring hinge cup holes in thicker cabinet door stiles and face-frame components where a standard 57mm hinge boring bit cannot achieve full depth - without requiring a separate extension.
- The negatively ground spurs and carbide cutting head work together to produce the flat-bottom, clean-walled 35mm cup hole that European concealed hinges require for a flush, secure fit - no secondary cleanup or chiseling needed.
- The PTFE-coated spiral and efficient twin-flute design reduce pitch adhesion and chip packing in composite materials like MDF and chipboard, which are among the most common substrates in cabinet production - keeping cycle times consistent and tool life predictable.
- The parallel shank with driving flat and length adjusting screw simplifies setup on multi-spindle boring machines and CNC boring centers, allowing operators to dial in exact cup depth quickly and hold that setting reliably across a full production run.
Specifications
- Manufacturer Part Number: 369.350.12
- Brand: CMT Orange Tools
- Diameter: 35mm
- 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
Approved Applications
- Drilling flat-bottom hinge cup holes in cabinet doors and panels
- European concealed hinge installation
- Cabinet door hinge cup boring in solid hardwood
- Hinge cup boring in softwood
- Hinge cup boring in chipboard
- Hinge cup boring in MDF
- Hinge cup boring in plywood
- Use in multi-spindle CNC boring machines (left-hand spindle positions)
- Use in CNC boring centers and panel processing centers
- Use in boring machines with adapter or chuck
- Use in drill press applications
Frequently Asked Questions
Why does this bit require left-hand (LH) rotation, and how do I know if my machine has the correct spindle?
This bit is precision-ground for left-hand rotation, meaning the cutting edges and negatively set spurs are oriented to cut correctly only when the spindle turns counter-clockwise (viewed from the chuck end). Multi-spindle CNC boring machines and panel processing centers typically include both right-hand and left-hand spindles arranged in a pattern to match standard hinge layouts. Consult your machine's spindle map or manual to confirm which positions are LH before installing this bit. Using a left-hand bit in a right-hand spindle will produce a rough, torn bore rather than a clean flat-bottom cup.
What is the purpose of the length adjusting screw on the shank?
The length adjusting screw allows the operator to set the precise insertion depth of the bit in the chuck or boring head before locking it in place. This means the hinge cup boring depth can be dialed in accurately and held consistently across a production run without re-measuring or trial drilling. The driving flat on the parallel shank prevents the bit from rotating in the holder under cutting load, keeping the depth setting stable.
What does the PTFE coating on the spiral do, and does it affect cutting performance?
The P.T.F.E. (polytetrafluoroethylene) coating applied to the spiral portion of the bit creates a low-friction surface that prevents pitch, resin, and glue from adhering to the flutes during drilling. This is especially valuable when boring into MDF, chipboard, or resin-coated materials common in cabinet production. The coating does not affect the sharpness of the carbide cutting edges - only the spiral body is coated, so cutting performance is maintained while chip evacuation stays clean and unobstructed.
Can this bit be used in a handheld drill or standard drill press, or is it only for dedicated boring machines?
This bit features a parallel shank (10 x 26mm) with a driving flat, which is compatible with chucks on drill presses and some handheld drills capable of accepting the shank diameter. However, the bit is specifically engineered for use in multi-spindle boring machines, CNC boring centers, and panel processing centers where left-hand spindle positions, consistent feed rates, and rigid workpiece fixturing are standard. For one-off or job-site hinge cup drilling with a handheld drill or drill press, confirm your chuck accepts the 10mm shank diameter and that the drill supports left-hand rotation before use.
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