31/64" Thunderbolt® Black Oxide Drill Bit

The Milwaukee 48-89-2737 is a 31/64" Thunderbolt® black oxide drill bit, part of Milwaukee’s jobber-length general-purpose drill bit series. It’s used for larger-diameter drilling in wood, metal, and plastic.

Key Features

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

Specs

• Size: 31/64 in (0.4844")
• Material: High-speed steel (HSS)
• Finish: Black oxide
• Length: ~5-7/8" jobber length
• Use: Metal, wood, PVC, plastics

Best Uses

• Large bolt and anchor holes
• Structural steel and fabrication work
• Construction framing and heavy assembly
• General jobsite drilling with larger fasteners

Bottom Line

The 48-89-2737 is basically the largest “standard” Thunderbolt bit in the range you’ve been listing so far. It’s still a general-purpose HSS drill bit, just sized for big fasteners and structural holes, not a specialty cobalt or masonry tool.