5/16" Thunderbolt® Black Oxide Drill Bit (6 PK)

The Milwaukee 48-89-2836 is a 5/16" Thunderbolt® black oxide drill bit set (6-pack) designed for general-purpose drilling in metal, wood, and plastic. It’s a step up from 1/4" sizes, commonly used for larger fasteners and clearance holes.

Key Features

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

Specs

• Size: 5/16 in (0.3125")
• Quantity: 6 bits per pack
• Material: High-speed steel (HSS)
• Finish: Black oxide
• Overall length: ~4-1/2 in (jobber length)
• Flute length: ~3-3/16 in
• Use: Metal, wood, PVC, plastics

Best Uses

• Drilling holes for 5/16" bolts and hardware
• Clearance holes for 1/4" fasteners
• General construction and framing
• Medium-duty metal drilling
• Shop and maintenance work

Bottom Line

The 48-89-2836 is a mid-to-large “workhorse” Thunderbolt size, bridging the gap between common 1/4" bits and larger structural sizes. It’s built for durability and repeat use, making it ideal for general construction, fabrication, and fastening applications—not specialty deep-reach or oversized S&D drilling