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Silver cobalt steel aircraft extension drill bit 12 inches long 3/8 inch diameter

Drill America

Drill America 3/8in x 12in Cobalt Aircraft Extension Drill Bit pneumatic accessory

SKU CH-K53C-58RJJ

A 12-inch cobalt aircraft extension bit with a 3/8-inch diameter and split point for heavy-duty drilling

  • Product typeDrill Accessories
  • 12-inch reach for deep-hole drilling
  • Cobalt steel resists heat in tough alloys
  • Split point starts on contact without walking
  • 3750 decimal size matches 3/8-inch chucks

3/8-inch Cobalt Aircraft Extension Bit

This 12-inch cobalt steel drill bit is built for heavy-duty drilling in tough alloys. The split-point tip reduces walking and starts holes cleanly without a centre punch. It suits maintenance technicians and metal fabricators who need extended reach in aircraft or structural work. Buyers needing a shorter flute or a different shank diameter should choose another tool.

Thermals, noise and power draw in normal use

The bit runs cool when used with proper cutting fluid and steady feed pressure. Cobalt steel resists heat build-up better than standard high-speed steel during prolonged cuts. Noise and vibration depend on the pneumatic driver and workpiece rigidity rather than the bit itself. Power draw is determined by the air tool supplying the rotation.

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 nameDrill America
Product typeDrill Accessories

Questions about this item

How do I fit the 12 inch cobalt aircraft extension drill bit into my pneumatic drill?

Insert the 3/8 inch shank fully into the chuck, tighten securely, and keep the bit straight to avoid wobble in the long flute.

When will the split point on this 3750 size cobalt bit need attention?

The split point dulls with heavy drilling; resharpen or replace the bit once cutting speed drops noticeably.

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