Chicago-Latrobe 42021 21/64 in 135 Degree Split Point Jobber Drill Bit

21/64-inch jobber drill bit

The Chicago-Latrobe 42021 is a jobber-length twist drill sized at 21/64 inch with a 135-degree split point. It is made from high-speed steel with a TiCN coating for wear resistance. The fractional size suits general-purpose drilling in metal, wood and plastic where a 0.3281-inch hole is required.

135-degree split-point geometry

The 135-degree point angle reduces thrust and helps the bit self-centre without a pilot hole. The split-point design improves chip ejection in deeper cuts. Because the bit has no coolant holes, it relies on external lubrication or peck drilling to manage heat in tougher alloys.

Fractional sizing and material limits

The 21/64-inch diameter handles typical maintenance and fabrication tasks in steel, aluminium and composites. The TiCN surface extends life in abrasive materials, yet the absence of through-coolant limits continuous deep-hole work in high-alloy steels. Users needing larger diameters or internal cooling should select a different tool.