3/8" Thunderbolt® Black Oxide Drill Bit

The Milwaukee 48-89-2730 is a 3/8" Thunderbolt® black oxide drill bit, part of Milwaukee’s standard jobber-length drill bit lineup used for general-purpose drilling in wood, metal, and plastic.

Key Features

• Black oxide coating – reduces friction and helps resist corrosion
• 135° split point tip – starts on contact and prevents walking for accurate drilling
• Thunderbolt reinforced web – thicker core improves 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: 3/8 in
• Material: High-speed steel (HSS)
• Finish: Black oxide
• Length: Jobber length (~5")
• Use: Metal, wood, PVC, plastics
  

Best Uses

• Larger bolt and anchor holes
• Structural metal fabrication
• Construction framing and heavy-duty assembly
• Sheet metal and light steel drilling
• General shop and jobsite drilling

Bottom Line

The 48-89-2730 is one of the larger standard sizes in the Thunderbolt black oxide series. It’s a general-purpose 3/8" workhorse bit, not a specialty cobalt or impact-rated bit—meant for reliable everyday drilling in common construction and fabrication materials.