Product Description
The CMT Hinge Boring Bit 19 x 57.5mm Left-Hand (LH) is a precision-engineered brad-point style bit designed for drilling clean, flat-bottom hinge cup holes in cabinet doors, face frames, and panel components. Built for use on boring machines equipped with adaptors or chucks, this left-hand rotation bit delivers the exact flat-bottom geometry required for European-style concealed hinge installation. With a tungsten carbide (HW) cutting head, a super-strength steel body, and a PTFE-coated cutter portion, it is engineered for consistent performance across hardwood, softwood, and panel materials such as MDF, chipboard, and plywood.
Key Features
- HW (Tungsten Carbide) Cutting Head with Precision Balanced Centre Point - delivers accurate bore entry and a true flat-bottom hole, which is essential for proper seating of European concealed hinges.
- 2 HW Precision Ground Cutting Edges (Z2) - two carbide cutting edges provide clean, consistent material removal with minimal tear-out, reducing the need for secondary finishing or cleanup.
- 2 Negatively Ground Spurs (V2) - the negatively ground spur geometry scores the wood fibers ahead of the cutting edges, producing clean bore walls and sharp, chip-free hole perimeters in solid wood and panel products alike.
- PTFE-Coated Cutter Portion - the orange or black P.T.F.E. coating on the cutter portion reduces pitch and glue buildup, which extends tool life and keeps the bit cutting freely through composite and resinous materials.
- Super-Strength Steel Body - the robust steel body resists flex and vibration under repeated boring machine cycles, supporting dimensional accuracy across production runs.
- Parallel Shank with Driving Flat and Length Adjusting Screw - the 10 x 26mm shank with driving flat and length adjusting screw ensures secure, slip-free mounting in machine adaptors or chucks, allowing precise depth setting for repeatable hinge cup depth.
- Left-Hand (LH) Rotation - designed specifically for left-hand rotation spindles on multi-spindle boring machines and CNC boring centers, ensuring correct chip evacuation and bore geometry on LH-configured equipment.
Why This Product
- The negatively ground spurs and precision-balanced carbide centre point work together to produce the clean, flat-bottom bore geometry that European concealed hinges require - eliminating installation problems caused by rough or uneven hinge cups.
- The parallel shank with a driving flat and length adjusting screw allows the bit to be set to a precise boring depth, which is critical on production boring machines where consistent hinge cup depth is needed across every panel.
- The PTFE coating on the cutter portion actively resists pitch and adhesive buildup from engineered wood products like MDF and chipboard, keeping the bit performing longer between cleanings or replacements in high-volume cabinet shop environments.
- Specified as a left-hand rotation bit, this tool is the correct choice for LH spindle positions on multi-spindle CNC boring machines and boring centers - using the wrong rotation direction would cause poor cut quality and accelerated edge wear.
Specifications
- Manufacturer Part Number: 317.190.12
- Brand: CMT Orange Tools
- Diameter: 3/4"
- Total Length: 57.5mm
- Shank: 10 x 26mm
- Rotation: Left-Hand (LH)
- Number of Spurs: 2
- Number of Teeth: 2
- Tooth Geometry: Negatively ground spurs
- Material: HW (Tungsten Carbide)
- Product Type: Hinge Boring Bit
Approved Applications
- Drilling flat-bottom hinge cup holes in cabinet doors and face frames
- European concealed hinge installation
- Cabinet door hinge mounting in solid hardwood
- Hinge cup boring in softwood, chipboard, MDF, and plywood
- Use on boring machines equipped with adaptors or chucks
Frequently Asked Questions
What shank size and type does this bit use?
This hinge boring bit uses a parallel shank measuring 10 x 26mm. It includes a driving flat and a length adjusting screw for secure, precise mounting in boring machine adaptors or chucks.
Why is the left-hand (LH) rotation designation important?
Left-hand rotation means the bit is designed to spin in the opposite direction from a standard right-hand bit. Multi-spindle boring machines and CNC boring centers often have dedicated LH spindle positions. Using a correctly specified LH bit on those spindles ensures proper chip evacuation, clean bore walls, and accurate flat-bottom hole geometry. Using an RH bit on an LH spindle would produce poor results and accelerate tool wear.
What does the PTFE coating on the cutter portion do?
The P.T.F.E. coating applied to the cutter portion prevents pitch and glue from adhering to the bit during cutting. This is particularly beneficial when boring through engineered panel products such as MDF, chipboard, or resin-bonded plywood, where adhesive content in the material can cause buildup that degrades cut quality and increases friction.
What is the purpose of the negatively ground spurs on this bit?
The 2 negatively ground spurs (V2) score the wood fibers around the perimeter of the bore before the main cutting edges remove material. This action produces clean, chip-free hole walls and a sharp, undamaged hole rim - a key quality requirement when boring hinge cup holes in visible cabinet door surfaces where any tear-out would be cosmetically unacceptable.
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