Chicago-Latrobe 54120 135° Cobalt Jobber Drill Bit .3680

Heavy-Duty Cobalt Jobber Bit

The Chicago-Latrobe 54120 is a cobalt steel drill bit built for heavy-duty drilling in tough materials. Its 135-degree split point reduces walking and starts holes cleanly without a centre punch. The bit suits professional workshops and maintenance teams that need reliable performance on stainless steel, cast iron and high-strength alloys.

135-Degree Split Point Geometry

The split-point design self-centres on contact, limiting the need for pilot holes in many applications. Cobalt construction resists heat better than standard high-speed steel, extending edge life when drilling abrasive or work-hardening metals. The TiN coating further reduces friction and wear, though the bit is not coolant-fed, so chip evacuation relies on regular pecking.

Standard Jobber Shank Fit

The straight shank fits any three-jaw chuck or collet that accepts jobber-length bits, so no special holders are required. Common issues include premature dulling if feed pressure is too light, causing rubbing instead of cutting, and breakage if the workpiece shifts during deep holes. Use cutting fluid and maintain steady pressure for best results.