15/64" Thunderbolt® Black Oxide Drill Bit

The Milwaukee 48-89-2721 is a 15/64" Thunderbolt® black oxide drill bit used for general-purpose drilling in metal, wood, and plastic, typically for medium-to-large hole sizes in fabrication and construction work.

Key Features

• Black Oxide Coating – Reduces friction and improves corrosion resistance for longer life
• 135° Split Point Tip – Starts on contact and prevents walking for accurate drilling
• Thunderbolt Web Design – Thicker core adds strength and resists breakage under side load
• Parabolic Flute Design – Clears chips quickly to keep the bit cooler and drilling faster
• 3-Flat Secure-Grip Shank – Reduces slipping in the drill chuck

Specs (typical)

• Size: 15/64 in
• Material: High-speed steel (HSS)
• Finish: Black oxide
• Use: Metal, wood, PVC, plastic
• Length: Jobber length (~3-7/8")

Best Uses

• Medium/large pilot holes for bolts and anchors
• General metal drilling (sheet metal, brackets, light steel)
• Wood construction and framing
• Plastic/PVC fabrication
• Everyday shop drilling tasks

Bottom Line

The 48-89-2721 is a standard larger “workhorse” drill bit size in Milwaukee’s Thunderbolt line. It’s not specialty (like cobalt RED HELIX)—it’s meant for reliable everyday drilling when you need a solid 15/64" hole in common materials.