1/2" Thunderbolt® Black Oxide Drill Bit

The Milwaukee 48-89-2738 is a 1/2" Thunderbolt® black oxide drill bit, and it’s the largest size in the 48-89-273x series you’ve been going through. It’s designed for heavy-duty, general-purpose drilling in metal, wood, and plastic.

Key Features

• Black oxide coating – reduces friction and improves corrosion resistance
• 135° split point tip – starts on contact and helps prevent walking for accurate drilling
• Thunderbolt reinforced web – thicker core for higher strength and reduced breakage under load
• Parabolic flute design – clears chips quickly for cooler, faster drilling
• 3-flat Secure-Grip shank – reduces slipping in the drill chuck

Specs

• Size: 1/2 in
• Material: High-speed steel (HSS)
• Finish: Black oxide
• Length: ~6 in jobber length
• Use: Metal, wood, PVC, plastics
  

Best Uses

• Large bolt and anchor holes (heavy hardware installs)
• Structural steel and fabrication work
• Construction framing and heavy assembly
• Thick wood drilling and shop fabrication
• General jobsite drilling with large fasteners

Bottom Line

The 48-89-2738 is the heaviest-duty “standard” Thunderbolt bit size in this sequence. It’s not cobalt or specialty-grade—it’s still a general-purpose HSS bit, but sized for big structural holes where strength and chip clearing matter most.