Chicago-Latrobe 54105 135° Cobalt Jobber Drill Bit .2570

Purpose and user

The Chicago-Latrobe 54105 is a cobalt jobber-length drill bit sized to decimal equivalent .2570 with a 135-degree split point. It serves machinists and maintenance technicians who need a durable bit for drilling hard metals such as stainless steel and high-strength alloys. The TiN coating and cobalt substrate target users who prioritise tool life over lowest cost.

Sustained-load behaviour

Under continuous drilling the cobalt construction resists heat softening better than standard high-speed steel, while the TiN surface reduces friction and edge wear. The 135-degree split point is self-centring, so it maintains accurate hole placement without a centre punch even when the bit temperature rises during extended cuts. No coolant-through capability means the operator must supply external lubrication for deep holes.

Deciding specification

The critical figure is the decimal size .2570, which corresponds to letter-size F; if the drawing calls for a different diameter this bit will not produce the required hole. The 135-degree point angle and split-point geometry suit hard materials but may wander in very soft or thin workpieces. No coolant holes are present, so deep-hole drilling requires Peck cycles or frequent withdrawal.