Chicago-Latrobe 42785 135° Jobber Drill Bit O .3160 TiAlN

Chicago-Latrobe 42785 Jobber Drill Bit

The Chicago-Latrobe 42785 is a high-speed steel jobber drill bit sized to letter O with a decimal equivalent of .3160. It features a 135 degree split point designed for accurate starting and reduced walking in metalworking applications. A TiAlN coating provides increased hardness and heat resistance for extended tool life. This bit suits machinists and maintenance technicians drilling medium-duty holes in ferrous materials.

Sustained drilling performance with TiAlN coating

Under continuous load the TiAlN surface maintains hardness at elevated temperatures better than uncoated high-speed steel. The 135 degree split point geometry reduces thrust requirements, which helps preserve cutting edges during repeated operations. As a non-coolant-through design with zero coolant holes, heat evacuation relies on chip clearance and external lubrication. Heavy-duty web construction adds rigidity to resist deflection in deeper cuts.

Installation fits standard drill chucks

The straight shank seats directly into three-jaw chucks and quick-change adapters without additional bushings. Split-point geometry eliminates the need for centre punching in most materials, reducing setup time. Common issues include premature wear if cutting fluid is omitted in stainless or high-alloy steels, and chatter if the workpiece is not rigidly clamped. Re-sharpening must preserve the 135 degree angle to retain self-centring behaviour.