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Cobalt jobber drill bit with gold TiN coating, split point, 135-degree angle, size .3970

Chicago-Latrobe

Chicago-Latrobe 54123 135° Cobalt Jobber Drill Bit .3970

SKU CH-WYR9-KPCMM

A 135-degree split-point cobalt jobber drill bit sized at .3970 for hard-metal drilling

  • Product typeDrill Bits
  • 135° split point starts holes accurately without walking
  • Cobalt steel resists heat for longer cutting life
  • TiN coating reduces friction and extends sharpness
  • .3970 decimal size matches letter-gauge specifications
  • Jobber length provides standard reach for general drilling

Chicago-Latrobe 54123 Cobalt Drill Bit

The Chicago-Latrobe 54123 is a jobber-length drill bit made from cobalt steel with a titanium nitride coating. It features a 135-degree split point designed for self-centering and reduced thrust. The decimal equivalent size is .3970 inches, identified as a letter gauge. This accessory targets professionals and serious DIY users drilling hard metals.

135-degree split point and TiN coating

The 135-degree split point geometry allows the bit to start on contact without a centre punch, improving accuracy in tough alloys. Cobalt construction resists heat buildup during extended drilling cycles in stainless steel or cast iron. The TiN coating adds surface hardness and lubricity, extending tool life compared to uncoated high-speed steel bits. No coolant holes are present, so external lubrication is recommended for deep holes.

Suited for stainless steel and high-temp alloys

This bit suits machinists and maintenance technicians who regularly drill stainless steel, titanium, or other work-hardening materials where standard bits dull quickly. The jobber length provides standard reach for most bench and handheld applications. Buyers needing coolant-through capability for deep-hole production runs should look elsewhere. Users requiring larger diameters or metric sizes not matching .3970 will need different tooling.

How it compares

Measured against everything we stock in Bits, Hole Saws & Accessory Kits, at today’s prices. Recalculated every night.

Price $16.99
Cheaper than about 70% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameCHICAGO-LATROBE
Product typeDrill Bits

Questions about this item

When will the cobalt jobber drill bit need resharpening or replacement?

The 135° split-point cobalt tip resists wear longer than standard steel, but will eventually dull; resharpen with a cobalt-capable grinder or replace when cutting edges no longer centre cleanly.

What limits continuous drilling with this bit?

Heat buildup in the workpiece is the first limit; the non-coolant-through design means you must pause for chip clearing and cutting fluid to prevent the .3970 diameter from overheating.

How much noise and heat does the bit generate during all-day use?

The bit itself runs silently; all noise comes from the drill motor, while heat stays in the workpiece — use steady feed pressure and coolant to keep the cobalt tip from discolouring.

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