The Best Drill Bits Tested in 2023

Yes, cheap HSS drill bits can drill a soft metal like aluminum, but aluminum’s low melting point becomes problematic with HSS bits due to heat buildup with extended use. For the cleanest, most precise results, heat-resistant cobalt-alloy bits—such as those in this Irwin set—make the best choice.

The Irwin M35 cobalt metal index drill bit set includes 29 bits, from 1/16-inch to ½-inch sizes, in 1/64-inch increments. They are purpose-built for a long working life while drilling metal. The M35 alloy steel exhibits excellent heat and wear resistance for long-term drilling durability. Heavy-duty web construction and 135-degree split-point tips allow the bits to drill metal fast and efficiently. And the bits are easy to sharpen when needed for an even longer work life. This drill bit set is conveniently packaged in a rubber overmolded steel carry case with removable cartridges for easier transport.

The Irwin cobalt drill bits performed exceptionally well in my tests, using them to drill cast iron and stainless steel in addition to cast aluminum. The tips drilled accurately with no walking on the metal surfaces, and they remained sharp, leaving clean edges on all of the test holes. I also appreciated that the larger bits are machined down at the shank to fit ⅜-inch drill chucks. The smooth shanks chucked securely into my drill press, but I had to double-check the grip in my cordless drill chuck.

The only weak points I noticed were in regard to the storage case, which features a sliding latch that sometimes becomes misaligned or sticks in place. The set is probably best for shop use only rather than carrying around in a tool box. The plastic cartridges that hold the bits in place are removable “for transport,” but the kit has no other carry case to insert the cartridge into. I did like that a tap and drill selection chart is included in the case, however. While the case could stand some improvement, the high-quality bits and moderate price point make this Irwin set worthwhile.

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Get the Irwin drill bits at Amazon or Acme Tools.