10 Best Metal Cutting Drill Bits in 2026

A 21-piece set with M42 cobalt bits that go up to 1/2 inch gives you the core sizes for drilling into tough materials like stainless and cast iron without paying for fillers you’ll never use. The no-skate tip and three-flat shank mean you spend less time chasing a wandering bit or tightening a slipping chuck. That combination of a practical size range, the right material for hard metals, and thoughtful anti-slip features is what makes this set a reliable first pick for most shops.

You do need to use cutting fluid for the best life, especially on abrasive or work-hardened metals, as the cobalt can still wear. For a pure hole-count comparison, the 29-piece sets from brands like Milwaukee or Drill America offer more bits in the same size range. But if your bench drill sees a mix of stainless, titanium, and lighter metals, the Bosch CO21 delivers focused value without the bulk.

Bosch builds these bits from an 8% cobalt M42 alloy, a material engineered to deliver ten times the life of standard bits when drilling into metal. That durability and high heat resistance means you can tackle stainless steel or cast iron without the tip immediately failing. The set includes a practical spread of fourteen sizes, from a fine 1/16-inch up to a substantial 1/2-inch, which handles most common metal drilling tasks straight from its compact case.

These bits are noted as a popular, affordable choice for handling hardened steel, though research mentions they can wear more quickly on work-hardened material without cutting fluid. For more pieces within the same 1/16-inch to 1/2-inch range, a set like the 29-piece Drill America cobalt offers greater quantity. If your work frequently involves tough alloys and you prioritize a reliable, budget-friendly set, these Bosch bits deliver focused performance.

A 29-piece set of M35 cobalt bits offers a serious range for tackling most metal drilling jobs outside a machine shop. This is the set you grab when you need to drill through general steel with a cordless drill and want a balance of durability and value. It’s built for the tradesman or advanced DIYer who needs a wide assortment of common sizes ready to go, all housed in a single, sturdy case.

The trade-off is specificity. These are strictly fractional bits, so if your project requires precise tap drilling for threading with number or letter sizes, you’ll need to look elsewhere, like a set from Drill America or Norseman. Compared to a more compact set like the Bosch CO21, the Milwaukee’s case and bit range are far more comprehensive but also bulkier. For the majority of metal fabrication and repair work, however, this set’s breadth and reliable cobalt performance make it a foundational kit for the workshop.

Cobalt alloy steel with 5% cobalt gives these bits higher heat and abrasion resistance, which helps them stay sharp when drilling into hard metals. The set covers 29 sizes from 1/16 inch up to 1/2 inch in fine increments, so you have a precise bit for most common metalworking tasks. Heavy-duty web construction adds strength, making them less likely to snap under pressure in a busy shop.

The case measures 12.3 inches wide, a size that fits a toolbox drawer better than a small portable bag. For a more compact cobalt set, the Bosch CO21 is under ten inches wide, though it contains eight fewer pieces. Some users report the three-flat shank on that Bosch model also works with impact drivers.

Impact-rated with a 1/4 inch hex shank, these bits lock directly into an impact driver to prevent the slippage common with round shanks. The titanium nitride coating lasts 2.5 times longer than non-coated bits, which means less frequent replacement when drilling tough materials like stainless steel. A 135-degree split point geometry provides faster starts and reduced walking for more controlled drilling in ferrous metal, wood, and plastic. This 14-piece set is a focused kit for users who value tool interchangeability over having every possible drill size.

The trade-off is in the selection. With 14 pieces, you’re getting a solid range for common tasks, but you won’t have the breadth of a 29-piece set like the Milwaukee Red Helix when a project calls for an obscure size. The hex shank is a performance advantage in an impact driver, but it’s a limitation if your primary drill is a keyless chuck. This Makita set excels as a dedicated, hard-use companion for an impact driver, prioritizing durability and secure fit over maximum versatility.

A 135-degree stepped split point is the key here. It bites into material with less walking and produces notably cleaner, smoother holes in sheet metal and acrylic compared to a standard point. This set is built for the tradesperson or serious DIYer who regularly drills into steel, brass, or hardened metals and values a clean finish. The M42 cobalt alloy handles the heat, and the three-flat shank keeps things secure under load.

The selection focuses strictly on fractional sizes from 1/16″ to 1/2″, which covers common needs. Research mentions these bits are used by construction tradesmen, and notes that few manufacturers in this category offer the numbered or letter drill bits found in a full machine shop index. For the core fractional sizes, however, the stepped point design aims to create smoother holes and can be used to enlarge existing ones.

Crosstar’s triple-flute geometry provides approximately 40% improved chip ejection over conventional bits, which helps keep the operation cooler during use. This design also offers superior hole roundness and wall finish. With M35 cobalt steel effective on materials up to 60 HRC and a TiAlN coating that withstands extreme heat, the set is engineered for tough alloys like stainless steel and titanium.

The triple-flute design is used for sizes 3/32″ and up, while the smallest bits from 1/16″ through 7/64″ use a two-flute pattern for delicate work. This means the performance benefits of the three-flute geometry are not applied to the entire size range. For a cobalt set with a different flute design, the Bosch CO21 is another option with a three-flat shank.

DEWALT’s titanium nitride coating is specified for longer bit life, a feature that aims to reduce replacement frequency. The set is listed as ideal for drilling in metal, wood, and plastics, covering a range of common workshop materials. Its speed tip is designed to reduce walking, which can help with starting holes accurately. The included case is intended to keep the 14 bits organized, a detail noted in the product features.

The 14-piece assortment provides a selection of common sizes, a count matched by other sets like the Bosch CO14B and Makita Impact Gold. For applications specifically in stainless steel or cast iron, other listed products like the Bosch CO21 are marketed for those materials. The DEWALT bits have no-spin shanks, a design meant to improve grip in a drill chuck.

A 21-piece set of high-speed steel bits with a 135° split point means you can start a hole on a curved metal surface without the bit skating away. This DEWALT set offers solid core features for the DIYer tackling a mix of materials like PVC, wood, and general-purpose metal drilling. The black oxide coating fights rust, and the parabolic flutes help clear chips, all without the cost of premium alloys. It’s a foundational kit that gets the job done on common shop projects.

This 21-piece set uses high-speed steel, a choice that defines its role. While other listed sets like the Bosch CO21 or Milwaukee Red Helix are made from cobalt for demanding metals, this DEWALT set is built for general-purpose drilling in metal, hardwood, softwood, PVC, and fiberglass. It’s a cost-effective solution for common shop tasks rather than frequent work on hard alloys.

A 29-piece set covering 1/16″ to 1/2″ in precise 1/64″ increments means you’re far less likely to be caught without the exact size you need for a bolt or tap. This is the core strength of the Drill America set. It’s built for the tradesman or serious DIYer who regularly tackles a mix of metals, from stainless to cast iron, and values having a complete fractional lineup ready to go. The M35 cobalt construction and gold oxide finish are practical choices for heat resistance and reduced friction, translating to fewer bit changes and cleaner holes in tough jobs.

The set is strictly fractional, so it won’t handle machine shop tasks needing numbered or letter-size bits for precise tapping. Research mentions that Drill America’s own M42 cobalt bits were selected as best for hardened metal, indicating a more specialized tier exists. For common construction and repair jobs, however, this collection’s range of sizes makes it a reliable, specification-minded set that keeps a full range of fractions on hand.