3/8" COBALT RED HELIX™ Drill Bit

The Milwaukee 48-89-2321 is a 23/64" RED HELIX™ cobalt drill bit designed for heavy-duty drilling in hard metals, especially stainless steel, alloy steel, and cast iron.

Key Features

• Cobalt Alloy Construction – Built for extreme heat resistance and long life in hard metals (up to ~10–15× vs. black oxide bits)
• RED HELIX™ Variable Flute Design – Aggressive 35° helix transitions to 15° for faster chip removal and reduced heat buildup
• QUADEDGE™ 135° Split Point Tip – Starts on contact and reduces walking for accurate hole placement
• Enhanced Tapered Web – Strengthens the core for better durability and reduced breakage
• 3-Flat Secure Grip Shank – Helps prevent slipping in the drill chuck

Best Uses

• Stainless steel (primary use)
• Hardened steel and structural metals
• Cast iron
• General fabrication and maintenance work

Bottom Line

The 48-89-2321 is a specialty cobalt drill bit for tough materials, not a general-purpose bit. It’s meant for jobs where standard titanium bits would overheat or wear out quickly—especially stainless steel drilling in fabrication or mechanical work.