Osg 10390605 Screw Machine Drill Bit 25/64 Cobalt Hss

Product Description

The OSG 10390605 is a screw machine length drill bit designed for high-performance drilling in steel and alloy steel workpieces. At 25/64 inch (0.3906 inches) diameter with a 130-degree split point and cobalt high speed steel construction, this bit handles tough materials that standard HSS tooling struggles with. The shortened screw machine length improves rigidity and reduces deflection in production and maintenance drilling applications. A web-thinned, tapered web configuration reduces thrust and improves centering accuracy at the start of the cut. Licensed tradespeople and machinists working in industrial, mechanical, and HVAC fabrication environments rely on this bit for accurate, repeatable hole sizing.

This drill bit is suited for drilling steel and alloy steel in screw machine, drill press, and handheld power tool applications where a rigid, short-flute bit is preferred over jobber length. The straight-cylindrical shank fits standard drill chucks without adapters. With a flute-to-diameter ratio of 3xD and a regular spiral, chip evacuation stays manageable in through-hole and shallow-depth drilling. It is a solid choice for field fabricators, pipefitters, and maintenance machinists who need a reliable cobalt bit for ferrous metals.

Key Features

• Cobalt high speed steel construction for extended tool life in steel and alloy steel
• 130-degree drill point angle with R-thinned, tapered web for reduced thrust and improved self-centering
• Screw machine (stub) length improves rigidity and reduces deflection versus jobber length
• Right-hand cut, 2-flute spiral design with regular helix for efficient chip removal
• Straight-cylindrical shank fits standard drill chucks without additional tooling
• Diameter tolerance of +0 to -0.022 mm for consistent, close-tolerance hole sizing

Compatibility

Designed for use in steel and alloy steel workpieces. Fits standard drill chucks accepting a straight-cylindrical shank at 25/64 inch (0.3906 inches) diameter. Part of the OSG Series 1000 high performance drill line.

Installation Notes

This bit is installed and operated by machinists, pipefitters, or maintenance technicians using a drill press, screw machine, or handheld power drill with a keyed or keyless chuck. Secure the shank fully in the chuck before operation and verify chuck tightness to prevent slippage. Use appropriate cutting fluid when drilling steel to extend tool life and maintain hole quality. Always wear eye protection and secure the workpiece before beginning the cut.