Chicago-Latrobe 43790 135 Degree Heavy-Duty Jobber Length Drill Bit

Jobber-length drill bit for T-size holes

This Chicago-Latrobe drill bit is a jobber-length twist drill sized to letter T with a decimal equivalent of .3580. It is manufactured from high-speed steel and finished with a TiCN coating for extended wear resistance. The 135-degree split point is designed to start on contact and reduce walking. It suits general-purpose drilling in metal and other materials.

135-degree split point and non-coolant design

The 135-degree point angle allows faster penetration in harder materials compared to shallower angles. A split-point geometry self-centres the bit, eliminating the need for a centre punch in many applications. The tool has no coolant holes and is not a coolant-through design, so chip evacuation relies on standard flute geometry and periodic withdrawal. This limits continuous deep-hole drilling without external lubrication.

TiCN-coated high-speed steel for T-size capacity

The TiCN coating increases surface hardness and reduces friction, letting the bit handle higher cutting speeds than uncoated high-speed steel. It comfortably drills the .3580-inch diameter in steel, cast iron and non-ferrous alloys. The jobber-length flute provides standard reach for through-holes and blind holes of moderate depth. The bit runs out of effective chip clearance in very deep holes or when drilling abrasive materials that demand internal coolant delivery.