M.a. Ford. 20633900 Screw Machine Drill Bit 0.339in Carbide

Product Description

The M.A. FORD. 20633900 is a screw machine length (stub length) drill bit machined from solid carbide stock. At 0.339 inches in diameter — letter size R — it features a 118-degree faceted point, a right-hand spiral flute, and a straight-cylindrical shank of equal 0.339-inch diameter. The shorter overall length of 2.5 inches increases rigidity compared to jobber-length bits, reducing deflection in demanding materials. Web thinning at the tip lowers thrust force and improves chip evacuation. This bit is intended for machinists, tool-and-die makers, and metalworking professionals running production or precision work on CNC equipment or drill presses.

The 20633900 is suited for drilling cast iron, non-ferrous metals, stainless steel, and carbon steel in short-hole applications where rigidity and hole accuracy are priorities. The 3xD flute-to-diameter ratio makes it well-matched to screw machine setups, gang drilling fixtures, and close-tolerance production drilling where a jobber-length bit would flex or wander. The bright uncoated finish is appropriate for applications where a lubricant or cutting fluid is used and coating adhesion is not required.

Key Features

• Solid carbide construction for hardness and wear resistance in ferrous and non-ferrous materials
• 118-degree faceted point with web thinning reduces thrust and improves centering
• Screw machine (stub) length — 2.5 inches overall — maximizes rigidity and minimizes deflection
• Right-hand spiral flute with regular helix for efficient chip evacuation
• Straight-cylindrical shank fits standard drill chucks and collet holders without modification
• Diameter tolerance of +0.0000 to -0.0005 inches supports close-tolerance hole requirements

Compatibility

Part of the M.A. FORD. Series 206 screw machine length carbide drill line, sized for letter R (0.339 inches) diameter applications in the 0.3000 to 0.3500 inch range.

Installation Notes

Solid carbide drills require a rigid, low-runout spindle — use a precision collet or chuck rated for carbide tooling rather than a worn or high-runout keyless chuck. Secure the workpiece firmly before engaging the spindle; carbide is brittle and will fracture under lateral shock loads. Apply appropriate cutting fluid for the workpiece material to extend tool life and maintain hole quality. Inspect the point for chipping before each use; a chipped carbide tip will oversized the hole and can break during the cut.