Drill America D Cobalt Heavy Duty Drill Bit Pack of 12 - Tough Metal

In this review of the Drill America D Cobalt Heavy Duty Drill Bit (Pack of 12), the bottom line is simple: these are workhorse jobber drill bits for anyone who regularly drills tough, high tensile metals and needs bits that stay sharp. The review finds they are best for metalworkers, fabricators, and maintenance shops because the cobalt steel construction and heat resistance allow higher cutting speeds and longer life compared with standard high-speed steel. The single biggest reason to buy is durability and performance when cutting stainless, inconel, or other hard alloys.

Key Features

• Cobalt steel construction: Provides higher red hardness so the bits tolerate heat better and cut harder alloys with less wear than typical high-speed steel.
• Gold oxide surface: A thin oxide finish reduces surface friction without masking cobalt identity, offering performance similar to uncoated bits while making size identification easier.
• Round shank: Works with a wide variety of toolholding systems so the bits fit standard chucks and collets reliably.
• Right-hand spiral flutes: Evacuate chips up and out of the cut to reduce clogging and keep holes cleaner during continuous drilling.
• Manufactured to NAS 907: Built to an aerospace standard that assures consistent geometry and tolerances for professional use.

Who It's For

These drill bits are geared toward professional tradespeople and serious DIYers who frequently drill hard metals such as PH stainless steel, inconel, and titanium, where bit life and heat resistance matter. Fabrication shops, maintenance crews, and anyone working with high tensile strength materials will benefit from the greater red hardness and ability to run at higher speeds.

Those who mainly drill wood, plastics, or soft metals for occasional household tasks may find standard high-speed steel bits more economical; this cobalt set is best when cutting performance and longevity justify the premium.

Pros & Cons

Pros

• Excellent durability and sharpness, with customers reporting longer life versus common cobalt competitors.
• Performs well at higher speeds due to heat resistant cobalt alloy, useful on stainless and nickels.
• Round shank and standard jobber length offer broad compatibility and predictable reach for general metalwork.

Cons

• Angle or point geometry received mixed feedback from some users, so results may vary by application.
• Gold oxide is a thin finish and offers limited additional wear protection compared with thicker coatings.

Specifications

Our Verdict

The Drill America D Cobalt Heavy Duty pack is a solid choice for professionals and serious hobbyists who need reliable, longlasting bits for stainless and other hard metals. They deliver good value through extended life and higher speed capability, making them a smart buy for repetitive metal drilling where toughness and consistent performance matter.

Frequently Asked Questions

Are these bits suitable for stainless steel?
Yes, the cobalt steel construction and higher red hardness make them well suited to drilling stainless and other high tensile alloys.

Will the round shank fit my drill?
The round shank is compatible with most standard chucks and collets, offering broad toolholding compatibility.

Does the gold oxide provide long-term protection?
Gold oxide is a thin surface treatment that helps identification and slightly reduces friction, but it does not replace a thicker protective coating for wear resistance.