The Greenfield Industries (Cleveland) part number 91842 (Style 183 / CTM-10) is a premium High-Speed Steel (HSS) metric counterbore with a Morse Taper 2 (MT2) shank and a continuous (solid) pilot. It is engineered explicitly for creating a flat-bottomed recess for industrial fasteners.
📐 Technical & Dimensional Specifications
- Manufacturer: Greenfield Industries (typically branded under their high-performance Cleveland line). [3, 4]
- Part Number (MPN): 91842 (often cataloged as C91842). [5]
- Style / Series: Style 183 / CTM-10 (Continuous Pilot Metric Series). [1, 2]
- Pilot Diameter: 11.00 mm — Designed to align seamlessly with an M10 clearance hole (standard fit) or an M12 tap-drill hole.
- Cutting/Counterbore Diameter: 18.00 mm — The target outer diameter of the pocket. This matches the standard head diameter of an M10 socket head cap screw, providing a flush or recessed professional fit.
- Shank Type: Morse Taper #2 (MT2) — Found on traditional drill presses, magnetic drills, or lathe tailstocks to deliver maximum torque transmission without slippage.
- Material: High-Speed Steel (HSS) with a bright/uncoated finish, providing excellent toughness and shock absorption. [5, 6]
- Flute Geometry: 3-Flute design — Formulated to provide optimal chip clearance and stability during heavy spot-facing or plunging operations. [1]
⚙️ Construction Benefits
Unlike multi-piece interchangeable tool systems, the Style 183 series features continuous/solid pilot construction. The pilot and cutter body are precision ground out of a single monolithic piece of HSS. This eliminates any micro-flexing or run-out between components, guaranteeing total concentricity between the initial bolt hole and the counterbored pocket.