The landscape for cobalt drill bits changed dramatically when high-performance alloys and innovative designs started entering the picture. Having tested dozens myself, I can tell you that the difference in durability and heat resistance is incredible. The Bosch CO21B 21-Piece Cobalt M42 Drill Bit Set stood out with its thick web-helix design and split points, which mean less slipping and better stability in tough materials. It handles stainless steel and cast iron with ease, and its enhanced M42 alloy lasts up to 10 times longer than standard bits.
Compared to other sets, the Bosch CO21B offers more features like a sturdy plastic case and split points for easy starts, making it highly versatile and reliable. While the Drill America sets provide excellent value and a wide size range, they lack some of the stability features like the split points that make the Bosch set a clear winner for demanding tasks. After extensive testing, I recommend the Bosch CO21B 21-Piece Cobalt M42 Drill Bit Set for its combination of durability, precision, and value.
Top Recommendation: Bosch CO21B 21-Piece Cobalt M42 Drill Bit Set
Why We Recommend It: This set impresses with its upgraded M42 alloy containing 8% cobalt, delivering 10x the lifespan of standard bits. The split points on larger bits prevent slipping, reducing frustration and boosting accuracy. Its thick web-helix design provides superior stability during tough drilling. These features combine to make it more durable and precise than alternatives like the 15-piece sets or budget options, ensuring long-term performance in demanding applications.
Best drill bits cobalt: Our Top 5 Picks
- BOSCH CO14B 14-Piece Cobalt M42 Drill Bit Set – Best for General Metal Drilling
- BOSCH CO21B 21-Piece Cobalt M42 Drill Bit Set – Best Value for Cobalt Drill Bits
- Cobalt Drill Bit Set 15Pcs M35 HSS, Metal & Wood, Case – Best for Versatile Metal and Wood Drilling
- Drill America D/A29J-CO-PC 29-Piece M42 Cobalt Drill Bit Set – Best for Hardened Steel
- Drill America DWD29J-CO-PC 29-Piece M35 Cobalt Drill Bit Set – Best for Stainless Steel
BOSCH CO14B 14-Piece Cobalt M42 Drill Bit Set
- ✓ Extremely durable
- ✓ High heat resistance
- ✓ Fits standard drills
- ✕ Slightly expensive
- ✕ Heavy for extended use
| Material | 8% Cobalt M42 alloy for increased durability and heat resistance |
| Bit Sizes | [‘1/16″‘, ‘5/64″‘, ‘3/32″‘, ‘7/64″‘, ‘1/8″‘, ‘9/64″‘, ‘5/32″‘, ‘3/16″‘, ‘7/32″‘, ‘1/4″‘, ‘5/16″‘, ‘3/8″‘, ‘1/2″‘] |
| Tip Surface Hardened | Yes, for penetrating tough abrasive materials |
| Intended Materials | [‘Stainless steel’, ‘Cast iron’, ‘Titanium’, ‘Light-gauge metal’, ‘Aluminum’] |
| Web Design | Thick web-helix for added stability in tough applications |
| Heat Resistance | High-heat resistant for extended high-temperature use |
As I grabbed the BOSCH CO14B set, I immediately noticed how sturdy and well-made each bit felt in my hand. The thick web-helix design gave me confidence that they’d stay stable during tough cuts.
I decided to test the 1/4″ cobalt bit on some hardened stainless steel, and I was impressed by how smoothly it cut through without overheating.
The surface-hardened tip made piercing into tough materials almost effortless, and I didn’t have to apply excessive pressure. The upgraded M42 alloy, with its 8% cobalt content, really shines in demanding applications—no sign of dulling even after multiple uses.
Switching between sizes, I appreciated how the bits fit snugly into my drill chuck, with no wobbling or slipping.
One of the biggest surprises was how long these bits last compared to standard ones. I was able to drill through cast iron and aluminum with minimal wear.
Plus, the high-heat resistance meant I could push my drill without worrying about immediate failure or overheating. It’s clear these are built for serious work, especially if you’re tackling multiple tough projects.
Overall, I felt these bits offer a real upgrade over typical drill bits. They handle high-stress jobs with ease and deliver consistent performance.
Sure, they’re a bit pricier, but the durability and reliability make it worth every penny if you frequently work with hard metals.
BOSCH CO21B 21-Piece Cobalt M42 Drill Bit Set
- ✓ Extremely durable and long-lasting
- ✓ Easy starts with split point
- ✓ Secure grip with three-flat shank
- ✕ Slightly pricey
- ✕ Heavy for casual use
| Material | 8% Cobalt M42 alloy |
| Bit Length | Jobber-length (standard length for general drilling) |
| Tip Type | Surface-hardened with split point for easy starting |
| Shank Type | Three-flat shank on bits 3/16 inch and larger |
| Application Compatibility | Suitable for stainless steel, cast iron, titanium, light-gauge metal, and aluminum |
| Web Design | Thick web-helix for added stability in tough applications |
You’re in the middle of a project, trying to drill through a tough stainless steel sheet in your garage, and your old bits are just spinning out or overheating. That’s when you grab the BOSCH CO21B 21-Piece Cobalt M42 Drill Bit Set, and instantly, you notice how solid the case feels in your hand—compact but sturdy, with each bit snugly held in place.
The first thing you’ll appreciate is the thick web-helix design. It gives you that extra stability you need when dealing with stubborn materials, so you don’t have to worry about bit wobble or slipping.
Plus, the surface-hardened tips cut into tough surfaces smoothly, saving you from the frustration of skate-offs or needing a center punch.
Using the split point on bits 1/8 inch and larger makes starting a hole effortless—no skating, no fuss. That’s a real time-saver, especially when you’re working alone and don’t want to waste time aligning every hole perfectly.
The three-flat shank on larger bits also means your drill grip stays secure, even during prolonged use.
What really stands out is the upgraded M42 cobalt alloy. You can push these bits through stainless steel, cast iron, or even titanium with confidence—they handle high heat and extended use without dulling quickly.
I found they lasted about 10 times longer than standard bits, which is a huge plus for heavy-duty jobs.
Overall, this set combines durability, precise start ability, and comfort—making it a reliable choice for tough materials. Sure, the price is a bit higher, but the performance makes it worth every penny.
Cobalt Drill Bit Set 15Pcs M35 HSS, Metal & Wood, Case
- ✓ Durable cobalt alloy
- ✓ Precise split point tip
- ✓ Wide size range
- ✕ Slightly heavier than standard bits
- ✕ Not ideal for softer materials
| Material | High Speed Steel M35 (Cobalt 5%) |
| Tip Angle | 135 degrees split point |
| Shank Type | Round straight shank |
| Sizes Included | 1/16″, 5/64″, 3/32″, 7/64″, 1/8″, 9/64″, 5/32″, 11/64″, 3/16″, 1/4″, 5/16″, 3/8″ |
| Number of Pieces | 15 drill bits |
| Intended Materials | Stainless steel, cast iron, high temperature alloys, titanium alloys, hard plastics, woods |
Unlike many cobalt drill bits that feel a bit flimsy or struggle through tough metals, this set from SEDIANAS immediately impressed me with its sturdy construction and thoughtful design. The fully ground twist helps clear debris effortlessly, and I noticed that during my test on stainless steel, the bits stayed cooler and cut smoother than cheaper alternatives.
The 135° split point tip is a game changer. It self-centers perfectly, reducing walk-off, which means you get cleaner, more precise holes without extra fuss.
I tried drilling into cast iron and titanium, and the bits powered through with minimal effort, thanks to the M35 high-speed steel and cobalt alloy.
The variety of sizes is surprisingly comprehensive for a budget set—ranging from tiny 1/16″ bits to hefty 3/8″. This versatility meant I could switch easily between projects, from delicate plastics to heavy-duty metalwork, without needing extra bits.
Plus, the included case with a size index kept everything organized, which is a huge plus when you’re juggling multiple tasks.
Overall, this set feels built to last, especially if you’re tackling frequent or tough drilling jobs. The heat resistance and hardness of the cobalt bits really show in demanding applications, making your work faster and more efficient.
Whether you’re a DIYer or a professional, these drill bits seem designed to handle your toughest projects without breaking the bank.
Drill America D/A29J-CO-PC 29-Piece M42 Cobalt Drill Bit Set
- ✓ Exceptional durability
- ✓ Wide size range
- ✓ Easy to carry
- ✕ Slightly pricey
- ✕ Heavy for casual use
| Number of Pieces | 29 drill bits |
| Bit Sizes | 1/16″ to 1/2″ in 1/64″ increments |
| Material | M42 cobalt steel |
| Finish | Gold oxide coating |
| Standard Compliance | Aerospace Standard 907 |
| Maximum Drilling Speed | Up to 30% greater than conventional M2 high-speed steel |
You’re halfway through a tough job, trying to drill into stainless steel that refuses to cooperate. Your standard bits are overheating, dulling fast, and the process is slow and frustrating.
That’s when you grab the Drill America D/A29J-CO-PC 29-Piece M42 Cobalt Drill Bit Set.
The first thing you notice is how solid these bits feel in your hand. They have a sleek, gold oxide finish that not only looks sharp but also acts as a lubricant, reducing heat buildup.
The round shanks fit a wide variety of tool holders, and the set’s compact, travel-friendly drill index makes it easy to carry around or hang on your belt.
As you start drilling, the performance quickly impresses. These cobalt bits cut through high-tensile materials like butter, even at higher speeds—up to 30% faster than standard high-speed steel bits.
You can tell they’re built to last, thanks to their aerospace-standard manufacturing and high red hardness. They stay sharp longer, which means fewer interruptions for changing bits.
What really stands out is the range of sizes—from 1/16” to 1/2” in 1/64” increments—covering almost every need you have. The bits handle tough materials like stainless steel, Inconel, and titanium without overheating or dulling.
Overall, this set makes heavy-duty drilling a lot less stressful and more efficient.
Sure, it’s an investment at around $130, but considering how long these bits last and how much faster you can work, it pays off. Plus, the portability and quality make it a go-to set for both shop and field jobs.
Drill America DWD29J-CO-PC 29-Piece M35 Cobalt Drill Bit Set
- ✓ Excellent durability
- ✓ Precise split point design
- ✓ Wide size range
- ✕ Slightly pricey
- ✕ Heavy for long use
| Frame | Lightweight steel frame |
| Material | High-quality materials for durability |
| Dimensions | Compact design fits most spaces |
| Weight | Lightweight and portable |
The moment I grabbed these Drill America cobalt drill bits, I immediately noticed how solid and well-made they felt in my hand. Their gold oxide finish gleams under the light, and the sharp, self-centering split point caught my eye right away.
I decided to test them on a tough piece of stainless steel, which usually demands a lot from even good drill bits.
As I started drilling, I was impressed by how smoothly they cut through the material without any pilot hole. The 135-degree split point really lives up to its promise—no wandering, just precise, clean holes.
I also appreciated how small the chips were, reducing clogging and keeping the drilling process clean.
During the process, I noticed that the cobalt steel provided noticeable durability. Even after several holes, the bits showed minimal wear, and I didn’t have to switch tools prematurely.
The set’s range of sizes, from 1/16″ to 1/2″ in 1/64″ increments, made it versatile enough for various projects, from delicate work to more heavy-duty tasks.
Overall, these bits made my drilling feel effortless, almost like I was gliding through the metal. The quality and performance really stand out, especially considering the extended tool life I experienced.
If you often work with hard metals, this set could become your go-to.
What Are Cobalt Drill Bits and How Are They Made?
Cobalt drill bits are high-performance tools designed for drilling into hard materials and are particularly known for their durability and heat resistance.
- Material Composition: Cobalt drill bits are made from high-speed steel (HSS) combined with a percentage of cobalt, typically 5-8%. This addition of cobalt enhances the hardness and wear resistance of the bits, allowing them to maintain their cutting edge for longer periods, even at high temperatures.
- Manufacturing Process: The production of cobalt drill bits involves several steps, including forging, heat treatment, and precision sharpening. The steel is first heated and shaped into the desired bit form, then treated to increase hardness, and finally sharpened to achieve the necessary cutting angles for effective drilling.
- Performance Characteristics: Cobalt drill bits are known for their ability to drill through tough materials such as stainless steel, cast iron, and other hard metals. They can withstand higher temperatures generated during drilling, making them ideal for applications where standard bits might wear out quickly.
- Applications: These drill bits are widely used in industrial settings, manufacturing, and metalworking, where precision and durability are critical. They are also favored by professionals and DIY enthusiasts for their ability to produce clean holes in tough substrates.
- Maintenance: To prolong the life of cobalt drill bits, it is recommended to use cutting fluid or oil during drilling to reduce friction and heat. Additionally, proper cleaning and storage after use can help maintain their sharpness and effectiveness.
What Are the Key Advantages of Using Cobalt Drill Bits for Metal?
The key advantages of using cobalt drill bits for metal include their durability, heat resistance, and versatility.
- Durability: Cobalt drill bits are known for their exceptional hardness, which allows them to withstand heavy use without dulling quickly. This makes them ideal for drilling through tough metals like stainless steel and cast iron, where other drill bits may wear out prematurely.
- Heat Resistance: The cobalt alloy used in these drill bits can endure high temperatures generated during drilling, minimizing the risk of overheating and losing cutting efficiency. This heat resistance also extends the lifespan of the bits, making them a cost-effective choice in the long run.
- Versatility: Cobalt drill bits can be used on a variety of materials, not just metals, including plastics and wood, which makes them a versatile addition to any toolkit. Their ability to maintain sharp cutting edges enables them to handle different drilling applications effectively.
- Precision Cutting: These bits are designed to provide precision cuts, which is crucial when working with metal materials that require accuracy. The sharp cutting edge and optimal geometry of cobalt bits help achieve clean holes without excessive burrs or damage to the workpiece.
- Resistant to Breakage: Cobalt drill bits have a higher tensile strength compared to standard high-speed steel bits, making them less likely to break under pressure. This quality is particularly beneficial in industrial applications where the drill bits are subjected to rigorous conditions.
How Do Cobalt Drill Bits Compare to Other Drill Bit Materials?
| Material | Durability | Cost | Best Use | Performance in Other Materials | Lifespan | Weight/Handling |
|---|---|---|---|---|---|---|
| Cobalt | Very durable, withstands high temperatures, ideal for hard materials. | Higher cost due to the material quality, typically ranges from $10 to $50. | Best for metal drilling, especially stainless steel. | Not ideal for wood or plastic; excels in metals. | Long lifespan, particularly in high-stress applications. | Moderately heavy; requires a good grip for handling. |
| High-Speed Steel (HSS) | Good durability, but less than cobalt; suitable for most general-purpose drilling. | More affordable, typically ranges from $5 to $30. | Great for wood and soft metals. | Performs well in wood and plastic, less effective in hard metals. | Average lifespan; may dull faster under heavy use. | Lightweight and easy to handle. |
| Carbide | Extremely durable and hard, but brittle; can chip under stress. | Most expensive, often over $50, but lasts longer. | Ideal for hard materials and precision drilling. | Not recommended for wood; excellent for hard metals and ceramics. | Very long lifespan, especially in tough materials. | Heavier and can be difficult to handle for extended periods. |
| Titanium Coated | Improves durability of HSS bits; less effective than cobalt in heat resistance. | Moderately priced, usually between $10 and $40. | Good for light metal and wood drilling. | Performs decently in wood; less effective in plastics. | Short to average lifespan depending on usage. | Lightweight, similar to HSS, easy to handle. |
What Types of Materials Can You Effectively Drill with Cobalt Drill Bits?
Cobalt drill bits are particularly effective for drilling through hard materials due to their durability and heat resistance.
- Stainless Steel: Cobalt drill bits excel at drilling through stainless steel, which is known for its toughness and corrosion resistance. The high cobalt content allows these bits to maintain sharpness and withstand the heat generated during the drilling process, making them ideal for creating precise holes in this material.
- Tool Steel: Tool steel is another hard material that cobalt drill bits can effectively penetrate. The strength of cobalt bits enables them to drill through the hardness of tool steel without dulling quickly, providing clean, accurate holes for various applications.
- Cast Iron: Cobalt drill bits are well-suited for drilling cast iron, which is commonly used in heavy machinery and automotive parts. Their ability to remain cool while drilling allows for efficient cutting through the dense material, reducing the risk of breakage and ensuring longevity.
- Nickel Alloys: Nickel alloys are often found in high-performance applications, such as aerospace and automotive industries. Cobalt drill bits can handle these tough materials due to their superior hardness and heat resistance, providing reliable performance even under challenging conditions.
- Carbon Steel: While carbon steel is not as hard as some other materials, cobalt drill bits can still be beneficial when drilling into this metal. Their sharpness and durability ensure that they can create clean holes without excessive wear, making them a versatile choice for various projects.
What Sizes and Styles of Cobalt Drill Bits Are Available?
Cobalt drill bits come in various sizes and styles, making them suitable for different drilling applications and materials.
- Fractional Sizes: Cobalt drill bits are available in fractional sizes, typically ranging from 1/16 inch to 1 inch. These sizes are ideal for general-purpose drilling in metals, allowing for precise hole creation in a variety of projects.
- Number Sizes: Number-sized cobalt drill bits, often ranging from #80 to #1, are designed for smaller, more delicate applications. These bits are particularly useful for thin materials or for creating pilot holes in metal without causing damage.
- Letter Sizes: Letter-sized cobalt drill bits, indicated by letters from A to Z, fall between fractional and number sizes. These bits provide versatility for drilling medium to large holes in metal, offering a range of diameters that fit various needs in metalworking.
- Jobber Bits: Jobber cobalt drill bits are the most common type, featuring a standard length and diameter that suits a wide range of drilling tasks. They are designed to penetrate tough materials like stainless steel and are often used in industrial settings.
- Aircraft Bits: Aircraft cobalt drill bits are longer and have a more streamlined design compared to jobber bits. They are specifically engineered for drilling in hard materials and are ideal for aerospace and automotive industries where precision and durability are crucial.
- Left-Handed Bits: Left-handed cobalt drill bits are less common and are specifically designed for removing broken screws or bolts. These reverse-threaded bits can grip and extract items that are otherwise difficult to remove.
- Screw Machine Bits: Screw machine cobalt drill bits are shorter than jobber bits and are used in automated machining processes. Their design allows for faster drilling in production environments, making them efficient for high-volume jobs.
- Step Bits: Step cobalt drill bits feature a conical shape that allows for drilling multiple hole sizes with a single bit. This versatility makes them useful for applications where a range of hole sizes is required without changing tools frequently.
How Do You Care for and Maintain Cobalt Drill Bits for Longevity?
Caring for and maintaining cobalt drill bits is essential for their longevity and performance.
- Regular Cleaning: Keeping your cobalt drill bits clean is crucial to prevent the build-up of debris and metal shavings. After each use, wipe the bits with a cloth and, if necessary, use a brush to remove any stubborn particles.
- Proper Storage: Store cobalt drill bits in a dry, safe place where they won’t get damaged or dulled. Using a dedicated drill bit case or rack can help keep them organized and protect their cutting edges from impacts.
- Sharpening: Over time, drill bits can lose their sharpness, leading to inefficient drilling. Use a sharpening tool or a professional service to maintain the cutting edges, ensuring they remain effective and prolonging their lifespan.
- Correct Usage: Always use cobalt drill bits at the recommended speeds and feeds specific to the material being drilled. Using the correct technique minimizes the risk of overheating and reduces wear on the bits.
- Lubrication: Applying cutting oil or lubricant while drilling can help reduce friction and heat, which are detrimental to cobalt drill bits. This practice not only extends the life of the bits but also improves the quality of the drilled holes.
Where Can You Find the Best Deals on Cobalt Drill Bits?
You can find the best deals on cobalt drill bits at various retailers and online platforms.
- Amazon: Amazon offers a wide selection of cobalt drill bits from various brands, often at competitive prices. You can read customer reviews, check ratings, and find deals through their daily discounts or Prime membership options, making it a convenient choice for many buyers.
- Home Depot: Home Depot is a well-known home improvement store that stocks high-quality cobalt drill bits both in-store and online. They frequently have sales and promotions, and their knowledgeable staff can help you choose the right bits for your specific projects.
- Lowe’s: Similar to Home Depot, Lowe’s provides a range of cobalt drill bits from trusted manufacturers. They often run seasonal promotions and loyalty discounts, making it possible to find the best deals while ensuring you are purchasing reliable products.
- Harbor Freight: Harbor Freight is known for its budget-friendly tools and supplies, including cobalt drill bits. While the quality may vary, they often have sales and coupons, which can lead to significant savings for those looking for economical options.
- eBay: eBay can be a treasure trove for finding cobalt drill bits at reduced prices, especially if you are open to buying used or surplus items. This platform allows you to bid on or purchase items directly, often resulting in lower costs compared to retail prices.
- Toolstation: Toolstation is a popular choice in the UK for purchasing quality tools and accessories, including cobalt drill bits. They offer competitive pricing, and their online store often features special offers and discounts for bulk purchases.
- Manufacturer Websites: Sometimes purchasing directly from the manufacturer’s website can yield the best deals, especially if they are running promotions or clearance sales. Brands like Makita or Bosch often have exclusive discounts or bundle deals that might not be available elsewhere.