Cobalt Heavy Duty Drill Bit Pack of 12 - Durable Jobber Length

Our review of the Drill America #74 Cobalt Heavy Duty Drill Bit pack finds it best for machinists, metalworkers and serious DIYers who regularly drill tough alloys. The bottom line: these are heavy duty jobber length bits made from cobalt steel that stay sharp and cut harder metals like stainless, inconel and titanium more reliably than standard high-speed steel bits. For anyone needing longer life and higher cutting speeds without exotic coatings, this pack delivers consistent performance and value for money.

Key Features

• Cobalt steel construction: delivers higher red hardness so the bits run up to about 30 percent faster and hold an edge when cutting high tensile materials.
• Gold oxide finish: provides a thinner surface treatment than black oxide while maintaining similar cutting performance and simplified identification of cobalt tools.
• Round shank: fits a wide variety of toolholding systems so the bits can be used in many drill chucks and holders without adapters.
• Right-hand spiral flute: evacuates chips up and out of the hole to reduce clogging and keep cuts clean in deep or long drilling operations.
• 118 degree point: offers a versatile, standard tip geometry that centers well and performs across common shop materials and tasks.
• Manufactured to NAS 907: built to a national aerospace standard that supports consistent dimensions and reliability for demanding applications.

Who It's For

These drill bits are ideal for professionals and hobbyists who work with hard, heat-resistant metals such as PH stainless steel, nickel alloys, inconel and titanium, where longer tool life and higher operating speeds matter. The pack format suits busy shops that want consistent replacements without mixing sizes from different makers.

Users who mainly drill wood or soft plastics and those looking specifically for coated performance gains (like TiN coatings for reduced friction) may prefer specialized bits designed for those materials; likewise casual users who rarely drill metal may find standard high-speed steel bits adequate and more economical.

Pros & Cons

Pros

• Excellent durability and sharpness retained over many holes, giving strong long-term value.
• Performs well on tough alloys and high tensile materials where HSS would struggle.
• Round shanks and standard points make the bits versatile across common drill setups.
• Manufactured to aerospace standard for consistent quality and sizing.

Cons

• Gold oxide is a thin finish and does not provide the same lubricity or wear resistance as thicker coatings, so users should still use proper speeds and lubrication when drilling hard metals.

Specifications

Series	D/ACO cobalt heavy duty
Material	Cobalt steel (heat resistant)
Point angle	118 degrees standard
Finish	Gold oxide surface treatment
Shank type	Round shank
Standards	Manufactured to National Aerospace standard 907

Our Verdict

These Drill America cobalt jobber bits are a sound purchase for anyone who frequently drills hardened or heat-resistant metals and needs reliable, long-lasting cutting performance. They strike a practical balance of durability, versatility and value for money, especially for metalworkers who want higher speeds and longer tool life than standard HSS offers.

Frequently Asked Questions

Are these bits suitable for stainless steel?
Yes. The cobalt steel composition and higher red hardness make them well suited to stainless and other tough alloys when used with correct speed and lubrication.

Do these have a special coating?
The bits have a gold oxide surface treatment, which is a thinner oxide finish used primarily for identification and basic corrosion resistance rather than a thick wear-reducing coating.

What shank fits my drill?
They have round shanks, which fit most standard chucks and toolholding systems but may require an adapter for keyed collets or quick-change hex chucks.