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Milwaukee 48-89-4631 THUNDERBOLT Cobalt Drill Bit Set

Milwaukee brand consistency for Milwaukee drill users

✎ PickHonest Research Desk▦ Updated October 15, 2026◷ 3 min read

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Milwaukee 48-89-4631 THUNDERBOLT Cobalt Drill Bit Set

Milwaukee

Milwaukee brand consistency for Milwaukee drill users

THUNDERBOLT cobalt
Milwaukee quality
15-piece

Pros

Milwaukee brand consistency for Milwaukee drill users
THUNDERBOLT cobalt rated for stainless and hardened steel
15-piece covers common sizes

Cons

15-piece vs Irw in 29-piece coverage

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Where the Milwaukee 48-89-4631 THUNDERBOLT Cobalt Drill Bit Set ranks

Best picksBest Drill Bits for Hardened Steel 2026: 10 Cobalt and Carbide BitsOur top pick for drill bits for hardened steel is the Irw in Cobalt Drill Bit Set 29-Piece (M42 cobalt with 8% cobalt content - highest cobalt grade for hardened steel).