Chicago-Latrobe 47723 23/64 in 135° Cobalt Jobber Drill Bit

Precision Cobalt Drill Bit

The Chicago-Latrobe 47723 is a jobber-length twist drill made from HAWA cobalt steel for drilling tough metals. Its 135-degree split point reduces walking and starts holes cleanly without a centre punch. The 23/64 inch diameter (0.3594 decimal equivalent) suits maintenance, fabrication and automotive work where standard high-speed steel dulls quickly. The straw-bronze surface identifies the cobalt grade and resists heat buildup.

135-Degree Split Point Limits

The split-point geometry self-centres on flat surfaces but can grab or chip on curved pipe, angled entries or thin sheet metal unless the workpiece is firmly clamped. Cobalt steel holds an edge at higher temperatures than standard HSS, yet it is more brittle; heavy feed rates or interrupted cuts risk corner breakdown. The tool has no internal coolant holes, so deep holes in stainless or titanium alloys require frequent pecking and external flood coolant to evacuate chips and control heat.

Installation And Common Issues

The straight shank fits any three-jaw chuck or collet sized for 23/64 inch; ensure jaws grip the shank fully, not the flutes, to prevent run-out. Because the bit lacks a reduced shank, it will not fit 1/2-inch-capacity chucks — a mismatch that is the most frequent cause of returns. Cobalt flutes work-harden if run at excessive speed with light feed; use the recommended surface-speed range for the material and maintain steady pressure to avoid glazing the cutting edges.