Chicago-latrobe 47890 Cobalt Jobber Drill 8mm 135 Deg

Product Description

The CHICAGO-LATROBE 47890 is a cobalt jobber-length drill bit engineered for demanding metal drilling applications. Built to Series 550ASP standards and conforming to NAS 907 Type B specification, it features an 8.00 mm diameter with a 135-degree split point that reduces walking on contact and lowers thrust requirements at entry. The straw-colored coating indicates the cobalt steel composition rather than a decorative finish. At 4.61 inches overall length with a 2.95-inch flute, this is a standard jobber proportion suited to general-purpose drilling in tight-tolerance metalworking environments. Right-hand spiral flutes with a web-thinned, tapered web configuration promote chip evacuation and improve cutting efficiency in tough substrates.

This drill bit is designed primarily for use on stainless steel and hardened materials where standard HSS tooling loses its edge prematurely. The cobalt alloy construction retains hardness at elevated temperatures generated during interrupted cuts or high-feed operations. Typical applications include maintenance machining, fabrication shops, aerospace repair, and field service work on stainless fasteners, structural steel, and similar ferrous alloys. It is sold individually but carries a minimum order quantity of 6 units, making it appropriate for toolroom stocking or job-site replenishment.

Key Features

• Cobalt steel construction retains cutting hardness in high-heat applications on stainless and hardened materials
• 135-degree split point reduces entry thrust and minimizes bit walking without a center punch
• Web-thinned tapered web improves chip flow and reduces torque demand at depth
• Straight cylindrical shank fits standard 3-jaw drill chucks without adapters
• NAS 907 Type B specification ensures dimensional conformance for repeatable hole sizing
• Diameter tolerance of +0.0000 to -0.0010 inches supports close-tolerance drilling

Compatibility

Designed as an OEM-style replacement and standard toolroom drill for use in any 3-jaw or keyless chuck accepting an 8.00 mm (0.3150 inch) straight shank. Primary workpiece materials listed by the manufacturer are stainless steel and hardened materials.

Installation Notes

Install and remove drill bits only with the machine fully powered down and the spindle at a complete stop. Secure the straight shank fully within the chuck jaws and verify concentricity before beginning a cut. Use appropriate cutting fluid or coolant when drilling stainless steel to reduce work hardening and extend tool life. Follow applicable shop safety standards and machine manufacturer guidelines for speed and feed selection based on workpiece material and thickness.