The Best Cobalt Drill Bits for Heavy-Duty Projects

When you need to bore through metal, cobalt is the only material that will do. Here’s the drill on some of the best cobalt bits you can buy. 

By Tony Carrick | Updated Dec 23, 2020 10:42 AM and its partners may earn a commission if you purchase a product through one of our links.

Best Cobalt Drill Bits


There aren’t many materials strong enough to put holes in hardened steel. When you need that kind of strength, the only answer is cobalt alloy drill bits. Cobalt drill bits are made of a steel alloy of 5 to 8 percent cobalt. These powerful bits will chew through cast iron, aluminum, and even steel. This guide will discuss key considerations when shopping for the best cobalt drill bits and highlight our top recommendations.

  1. BEST OVERALL: DEWALT Cobalt Drill Bit Set with Pilot Point
  2. RUNNER UP: IRWIN Drill Bit Set, M35 Cobalt Steel
  3. UPGRADE PICK: Drill America 20 Piece M35 Cobalt Drill Bit Set
  4. BEST FOR CAST IRON: Bosch CO14B Cobalt M42 Drill Bit Set
  5. BEST FOR STAINLESS STEEL: CO-Z 5pcs Hss Cobalt Multiple Hole Step Drill Bit
  6. BEST FOR BRONZE: Metric M42 8% Cobalt Twist Drill Bits Set
Best Cobalt Drill Bits


Before You Buy Cobalt Drill Bits 

Before you decide to purchase a set of cobalt drill bits, make sure you know what you’re getting. While these bits can cut a variety of materials, they are specifically designed to cut through hard metals such as stainless steel, cast iron, and even titanium. Because cobalt alloy bits are more expensive than conventional drill bits, they aren’t economical options for drilling materials like wood or masonry. Before making a purchase, make sure you’re buying the right drill bits for the right job.

Types of Cobalt Drill Bits 

Cobalt drill bits come in four different types, with each serving a specific purpose. Understanding the right application for each bit type is essential.


Twist bits have angled grooves that spiral around the drill shaft. The edges of these angles are sharp, allowing the bit to burrow into the material. Twist drill bits are for general-purpose use, meaning they can drill into many different materials. Cobalt twist bits are strong enough to bore into hard metals quickly. They come in a wide variety of sizes, with sets including up to 30 pieces.


Countersink drill bits create shallow holes that allow the head of a fastener to sit flush with the material and are angled to match the tapered head of the fastener. Cobalt countersink bits will create countersink holes in hard metals. Unlike twist drill bits, which include self-piloting tips, countersink bits require an existing hole to drill into a material.


Counterbore drill bits create holes that allow the head of a fastener to sit below the material’s surface. Unlike countersink bits, which create an angled hole for fasteners with angled heads, counterbore drill bits create a larger hole at a shallower depth. A counterbored hole creates a flat ridge on which the head of the fastener can rest.

Cobalt Step

Cobalt step drill bits are designed to drill holes into sheet metal. Step bits enlarge the hole as it moves through the sheet metal, allowing you to regulate its diameter. A step bit works with sheet metal up to 1/4-inch  thick.

What to Consider When Choosing the Best Cobalt Drill Bits

Before you grab the first set of cobalt drill bits you can find, take a moment to consider what you’ll need. Cobalt drill bits come in a variety of shapes and sizes to serve different needs.


Most twist bits come in diameters ranging from 1/16 to 1/2-inch. Step bits can drill holes ranging in diameter from about 1/8 to 1/2 inches, with a maximum depth of 1/4-inch. If you require deeper holes, you’ll need to purchase a twist bit.

Size also affects wear. Length negatively impacts durability. Long drill bits are not as durable as shorter bits. Due to the amount of torque needed to rotate longer bits, shorter bits also resist twisting or spinning in the drill chuck better.


The application you plan to use for the cobalt bit determines what type you will need.

  • Twist bits are general-purpose drill bits and are capable of drilling a variety of different materials.
  • If you’re looking to drill at shallow depths through sheet metal, then consider using a step bit.
  • If you need to drill countersink holes, then you’ll need twist bits to drill the initial hole and countersink drill bits to create the countersink holes.
  • Counterbore drill bits create recessed holes that hide the fastener head.

Cobalt Value

Cobalt drill bits consist of steel with a small percentage of cobalt—the higher the percentage of cobalt, the more heat-resistant and durable. The amount of cobalt in a drill bit varies between products. An M35 grade cobalt bit contains 5 percent cobalt, while an M42 grade cobalt bit contains 8 percent. The higher the grade, the more expensive the bit.

Tip Point

Given that you’ll be attempting to drill through a hard smooth surface, having the right tip is crucial. Most cobalt drill bits have tips with stepped and split points that bite into the metal, preventing the bit from sliding along the smooth surface instead of drilling into it.

Tips for Buying and Using Cobalt Drill Bits

Before buying or using a cobalt drill bit, it’s important to consider a few tips.

  • Don’t throw away dull drill bits. Instead, sharpen them with a grinder to restore their sharp edges.
  • Only use cobalt bits for drilling holes in metal, as the bits are too powerful for wood and other materials.
  • Drilling through steel, cast iron, and other metals produces tiny shards that can end up in your skin or eyes, so make sure to wear protective gloves and glasses when working with cobalt drill bits.

Our Top Picks

The cobalt drill bits on this list are top-of-the-line. They are durable, highly effective at boring through metal, and come from the most highly regarded manufacturers in the tool industry. Start your shopping here to pick up some of the best cobalt drill bits.

Best Overall

Best Cobalt Drill Bits DEWAIL

When drilling metal, some of the biggest headaches are bits that break, spin in the chuck, and bounce over the metal’s surface. DeWalt addresses all those issues with this set. High-grade cobalt and stainless steel enhance the durability of these drill bits, so you don’t need to worry about breaking a bit. A pilot point makes it much easier to get started and eliminates the need for a separate pilot hole. And Dewalt goes with a flat-sided shank to get rid of spinning issues.

This 14-piece set includes sizes ranging from 1/16 to 3/8 inches. Just keep in mind that, like most cobalt drill bits, heat becomes an issue when drilling through hard metals like stainless steel. Make sure to use a lubricant to keep things from heating up too much.


Best Cobalt Drill Bits IRWIN

You’ll have your pick of sizes of cobalt drill bits with this 29-piece set from Irwin. Sizes for these twist drill bits run from 1/16 to 1/2 inches in 1/64-inch increments. Each bit features a split-point top, which makes starting holes easier. The M42-rated bits are made from an alloy of steel and 8 percent cobalt, making it one of the toughest sets of cobalt bits you can buy.

Loose bits will eventually become lost bits. Irwin knows that, so this set comes with a convenient carrying case that securely indexes all 29 bits into three separate cartridges that fit neatly into a durable and portable rubber molded case.

Upgrade Pick

Best Cobalt Drill Bits DrillAmerica

Take your metal drilling to the next level with this set of premium cobalt drill bits from Drill America. It features 20 pieces that range in size from 1/16 to 1/2 inches in 1/64-inch increments. While the plastic carrying case may be fairly average, the quality of the bits is impressive. The gold finish acts as a built-in lubricant to keep heat levels down, making drilling through metal easier and extending the life of the bit. Each bit is made from high-grade M42 cobalt stainless steel alloy. A split point quickly penetrates hard metals without the need for a pilot hole.

Best For Cast Iron

Best Cobalt Drill Bits Bosch

With its M42 drill bits, this set from Bosch is ready to take on the hardest metals, including cast iron. This 8 percent cobalt alloy is more durable than M35 cobalt drill bits, giving it longer shelf life. Other features make drilling through metal a breeze. A split-point tip penetrates metal easily, while a flat shank prevents slipping in the chuck. Bosch goes with a thicker design than most spiral drill bits, which allows it to remove material more efficiently, decreasing the amount of time it takes to drill through metal. This set includes 14 pieces with sizes ranging from 1/16 to 1/2 inches.

Best For Stainless Steel

Best Cobalt Drill Bits CO-Z

This compact set fulfills nearly all the size demands you have for your cobalt drill set with 50 hole sizes. This step-drill bit set features five pieces. Each bit offers numerous increments that create holes ranging in size from 3/16 to 1/2 inches, with each step clearly labeled on one side of the bit. The bits are compatible with 1/4, 3/8, and 1/2-inch chuck sizes. A titanium coating provides additional durability. A convenient and durable compact metal carrying case conveniently stores the bits. Keep in mind that this step set is designed to drill holes into steel and aluminum sheets up to 1/4-inch in thickness.

Best For Bronze

Best Cobalt Drill Bits Metric

It takes a tough bit to drill through hard metals like steel and bronze. That’s why this M42 8% Cobalt drill bit from Metric is the bit for the job. Metric uses what it calls a three-step design with this drill bit. Borrowing from step bit technology, the tip of the bit is composed of three separate steps that help drive the bit through hard metals. Metric’s design allows the bit to be run at a higher speed, so you can drill faster and longer before the bit wears out. The proof of its power is in the waste—instead of chips ground by a dull bit head, the metal waste comes out as long strips cut by the drill’s edges. This 19-piece metric set features sizes ranging from 1 mm to 10 mm.

Best For Titanium

Best Cobalt Drill Bits COMOWARE

Cut through all the metal you want with this high-quality set of drill bits from Comoware. This set can take on all forms of hardened metal, including titanium. It includes 13 pieces with sizes ranging from 1/6 to 1/4 inches. Comoware uses a split-point tip with its twist design to clear particles quickly from the bit while preventing walking. This set comes with a convenient holder that keeps the bits organized and clearly labels them by size for easy indexing.

FAQs About Cobalt Drill Bits

Are you still wondering if cobalt bits are the best tool for the job? Read on for answers to the most common questions about cobalt drill bits.

Q. Can cobalt drill bits be sharpened?

While cobalt drill bits will hold up better against heat than other drill bits, they will need to be sharpened from time to time. Sharpen dull cobalt drill bits using a bench grinder.

Q. Are cobalt or titanium drill bits better?

Titanium drill bits are durable and will hold up much longer than standard high-speed steel drill bits, but they are not as strong as cobalt alloy, which will drill through hard metals, including titanium.

Q. What are the hardest drill bits?

M42 cobalt drill bits, which have 8 percent cobalt, are the hardest drill bits you can buy.