Cleveland Golf C15111 #21 Cobalt Drill Bit 135° Split Point TiAlN .1590

#21 Cobalt Drill Bit for Precision Drilling

This #21 size cobalt steel drill bit with a 135° split point is built for machine screw drilling in tough alloys. The TiAlN coating reduces friction and heat, extending tool life in repetitive production work. Its .1590 decimal equivalent suits precise hole preparation for tapping operations. Right-hand cutting direction matches standard drill presses and CNC setups.

Practical Limits of the 135° Split Point

The 135° split point centres quickly without a pilot hole, yet it still demands rigid clamping and steady feed pressure to avoid walking on curved surfaces. TiAlN resists wear at higher speeds, but the bit has no internal coolant channel, so deep holes require frequent pecking or external flood coolant. Cobalt steel handles heat better than high-speed steel, though it remains brittle if dropped or shocked.

Build Quality and Daily Implications

The cobalt substrate and TiAlN finish together resist edge chipping when drilling stainless or titanium, keeping hole size consistent across batches. A straight shank fits standard three-jaw chucks and quick-change holders without adapters. Non-coolant-through design means chips evacuate through flutes only, so clearing swarf regularly prevents packing and overheating during long runs.