27/64" Thunderbolt® Black Oxide Drill Bit

The Milwaukee 48-89-2733 is a 27/64" Thunderbolt® black oxide drill bit used for general-purpose drilling in wood, metal, and plastic. It’s one of the larger standard sizes in Milwaukee’s Thunderbolt lineup and is commonly used for large bolt, anchor, and structural fastening holes.

Key Features

• Black oxide coating – reduces friction and improves corrosion resistance
• 135° split point tip – starts on contact and prevents walking for accurate holes
• Thunderbolt reinforced web – thicker core increases strength and reduces breakage under load
• Parabolic flute design – clears chips quickly to reduce heat and improve drilling speed
• 3-flat Secure-Grip shank – helps prevent slipping in the drill chuck

Specs

• Size: 27/64 in (0.4219")
• Material: High-speed steel (HSS)
• Finish: Black oxide
• Length: ~5-3/8" jobber length
• Use: Metal, wood, PVC, plastics

Best Uses

• Large bolt and anchor holes
• Structural steel and fabrication work
• Construction framing and heavy assembly
• Sheet metal and light steel drilling
• General jobsite drilling tasks

Bottom Line

The 48-89-2733 is a large, standard-purpose drill bit—not cobalt or specialty. It’s basically the “big hole” version of the same Thunderbolt bits you’ve been listing: built for reliable everyday drilling in common construction materials, especially when working with 3/8" class hardware and larger fasteners.