9 Best Cobalt Drill Bits For Metal | Bits That Bite Hard Metal

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The big-bit specialist that bored 30 holes through double-layer steel with one tip.

Here is the brute-force answer when your project needs serious bite: five identical 3/8 inch x 5 inch bits in heavy-duty M35 cobalt. Where the RCINDUS set above focuses on versatility with small bits, this Sabre Tools pack is laser-focused on one job—boring clean, large holes through thick steel plate and structural iron without burning through your whole budget on a single bit. At 0.38 inches cutting diameter, each bit is over 50% wider than the 0.25 inch bits in the RCINDUS set, so it removes material far faster on heavy plate.

The pilot point tip (a self-centering point that bites immediately) prevents the skidding that plagues flat-tip bits on curved or angled steel. Owners mention one bit drilled 30 holes through 5/8 inch of steel per hole (two 5/16 inch layers) and stayed sharp with constant cold-water quenching. That kind of endurance comes from the heavy-duty M35 construction with superior resistance to abrasion and high heat.

This is the set for repair work, thick brackets, and automotive steel where you need speed and stability. It is not for intricate small work or for a drill press that runs at slow speeds without water cooling, since the 5-inch length demands a steady hand. For anyone who regularly drills 3/8 inch holes in thick steel, this set is the most efficient purchase you can make—one bit did an entire project, leaving four spares for the next job.

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The expanded index that cuts stainless “like a hot knife through butter.”

This 17-piece STROTON kit stretches from 1/16 inch pilot bits all the way up to a full 1/2 inch, making it the middle ground between the small RCINDUS pack and the mega 29-piece kits. It is the set a homeowner or light fabricator reaches for when they need to drill everything from tiny sheet-metal pilot holes to larger 1/2 inch mounting holes in steel or iron plate. The steel is premium 5% cobalt rated at 68 HRC, and the cutting edge is ground three times for a keen, precise bite.

What sets this index apart from the 13-piece STROTON set below is the inclusion of those larger, harder-to-find sizes like 5/16, 3/8, and 1/2 inch. The toughness of the edge is the headline—customers note the bits slice through stainless steel “like a hot knife through butter,” leaving sharp, clean holes, A 76-year-old woodworker calls it the highest quality set he’s owned for steel and iron plates. Even sheared bolts are no match; the bits chew through with steady pressure.

This is a true split-point design for self-centering, and the two-flute twist clears chips efficiently. It’s a step up in both price and capability from entry-level sets, but the cost-per-hole over a long life is where it pays off, as The maker notes you can run two to three times faster than standard bits. Just remember cutting oil and slow speeds for the hardest steels, since cobalt is hard but brittle.

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The legacy name that just works, designed for modern keyless chucks.

IRWIN brings a 15-piece kit with a design detail most budget sets ignore: a three-flatted shank that grips tight in keyless chucks (the standard twist-and-tighten chuck on modern drills) without slipping, so you can lean into a hole without the bit spinning free. The case has a clear lid so you can see what’s inside without opening it, and the case itself stacks neatly with other IRWIN organizers—a small comfort if you keep a wall of toolboxes.

For high-strength steel on cars and thick sheet, this is the set users report going through 3/8 inch steel plate “like butter,” especially when paired with cutting fluid. Multiple owners note the cobalt edge holds up far better than the cheap HSS bits they used to burn through, with some replacing three broken high-speed steel drills on a single job with one IRWIN bit. The 135-degree tip is a redesigned profile aimed at promoting longer life and easier starting.

Where this set trades blows with the STROTON kits is the mix: it includes multiple pieces of the smaller, more easily broken bits—a smart touch for real-world use. The honest caveat is that it’s pricier than the RCINDUS value pick for fewer total bits, and it is not marketed for hardened steel, so treat it as a premium all-rounder for automotive and mild steel rather than a tool for cutting through annealed armor plate. The hard plastic case is sturdy, though one user dinged a star purely on cost.

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The full 1/4-inch-index champion with a steel case that takes a beating.

This 21-piece STROTON set is the balance for anyone who wants complete 1/64-inch incremental coverage from 1/16 inch up to 3/8 inch—every size between, no gaps, which matters when you need a precise pilot hole before opening up to final diameter. It is the same premium 5% true cobalt steel rated at 68 HRC as its sibling, but wrapped in a genuinely tougher package: a Q235 cold-rolled steel plate case that opens and closes smoothly and protects the bits far better than the plastic boxes on cheaper sets.

The endurance story here is what earns it a spot on the shortlist. Reviewers point out one bit drilled 16 holes in 5/8 inch steel and 60 in 3/16 inch steel with almost no visible wear. A professional user who burns through bits daily calls these as good as any they’ve tried. That level of performance comes from the triple-ground, fully ground process that creates the long iron-chip cutting action instead of slow grinding wear.

This is the index to grab if you want the durability of the larger STROTON sets but do not need the 1/2 inch bits that clog up a 3/8 inch chuck. The split-point design self-centers, and the case’s steel construction means it survives the toolbox, not just the workbench. The trade-off is that the premium steel case and extra sizes push the price up slightly from the 13-piece STROTON set.

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The 29-size index that drills out snapped taps and turbo studs on the daily.

For the mechanic and fabricator who needs one box to cover every fractional size a shop might throw at it, this WildBossy 29-piece kit runs the full gamut from 1/16 inch up to a full 1/2 inch. It is built from M35 cobalt steel hardened up to 67 Rockwell, with a gold oxide surface finish and a 135-degree split point, and it ships in a metal indexed storage case that keeps every bit in its labeled slot.

This is the set that earns its keep on the most miserable jobs in metalwork: drilling out snapped-off taps and sheared studs. Shoppers say using it to drill out broken fasteners in turbo housings, cutting through thick multiple layers of metal, and breezing through 1/8 inch sheet iron with a single pass. The 3-flute twist design clears chips faster than standard 2-flute bits, and the gold oxide finish helps reduce friction as the bit sinks in. The recurring note is clear—this set makes easy work of jobs that “regular bits couldn’t handle.”

Just know it is not for glass or ceramic, and cobalt’s hardness means you must respect speed and pressure to avoid shock-breakage on hard steel. The case and full range make it a strong centerpiece for a serious toolbox, though the sheer number of bits means some sizes you may never touch. It is heavier and pricier than the value sets, but for anyone who has snapped a tap flush in an engine block, the cost is trivial next to the time it saves.

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The only metric index on the list, spanning 1.0mm to 13.0mm in a painted metal box.

If your work lives in millimeters—European cars, imported machinery, precise small crafts—this is the set that stops you from converting fractions and guessing. MACXCOIP packs 25 metric bits from 1.0mm up to 13.0mm, each one a 135-degree self-centering spear-point twist bit made from M35 cobalt steel. The blue case is painted metal, and the drill holders are metal too, not the flimsy plastic trays cheaper sets use, so the whole kit feels substantial in the hand.

The sharpness from the factory is the headline. Buyers report the bits arrive keen and stay that way even under heavy use, cutting through metal “like butter” while the hardened, polished inserts drill without wobbling. For small crafts and precision holes, the 1.0mm through 3.0mm bits are sturdy enough for delicate work yet sturdy cobalt, and the 13.0mm top end covers solid structural work. The 135-degree angle helps the bit self-center to prevent walk-off, and the quick chip removal keeps holes clean.

The honest caveat is that cobalt still demands finesse on super-hard metals like stainless—owners note you need cutting oil and must back off to clear shavings meticulously, and one buyer found the bit dulled halfway through a 1/4 inch mild steel hole despite slow speed. It is not marketed for quenched bolts, so treat it as a premium metric set for standard steel, iron castings, copper, aluminum, plastics, and wood. As the go-to suggestion for metric-only users, it beats fractional sets that leave you hunting for the right conversion.

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The entry price into real cobalt, from a brand that owns its own mine.

This is the set that introduces you to what 5% cobalt actually does, at the lowest entry point on this list. STROTON’s 13-piece kit spans 1/16 inch up to 1/4 inch in clean 1/64-inch increments, and the maker makes a bold claim: the bits come from their own cobalt ore mine, so the marked 5% cobalt content is real, not just printed on a label. That translates to material rated at 68 HRC, built to take on stainless steel, steel plate, iron sheet, and cast iron.

The performance story here is about technique as much as the steel. Owners mention the bits handle 10.9 hardened steel bolts—a high-strength grade—provided you use oil, go slow, apply firm pressure, keep the bit straight, clear chips, and cool frequently. The split-point design and fully ground process make it suitable for heavy-duty work like cutting through stainless and drilling out bolts and studs, and The maker rates it for 3 times the heat, wear, and chip resistance of ordinary bits.

For the home DIYer and light repair work, this is the smart money move: a real cobalt set at a budget-friendly price that outperforms the generic HSS bits in a typical hardware store drawer. Existing owners keep it in the drill bag and praise how well it works “on several surfaces.” The catch is the same one that applies to all cobalt—it’s brittle, so avoid bending or overloading, and the small 1/4 inch maximum means you will need a second set for larger holes. But for pilot holes, small fasteners, and sheet metal, this is the best cheap entry into the category.

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The 700-hole overachiever that keeps drilling long after cheaper bits give up.

COMOWARE delivers the most complete fractional index on this list—29 bits covering every size from 1/16 inch to a full 1/2 inch—in a metal indexed storage case with a size chart. Each bit is made from high-speed steel with 5% cobalt for superior wear, heat, and abrasion resistance, and the 135-degree split point is designed for self-centering quick-cut tips that penetrate with minimal pressure. The twisted shank geometry efficiently clears metal shavings as you drill.

The endurance numbers here are the stuff of shop legend. Customers note one bit drilled 700 holes through 1/2 inch aluminum at 6,000 rpm with lubrication, then handled mild steel by hand without dulling. That is the payoff of real 5% cobalt when you respect speed and use lube. Owners also note the bits cut through stainless steel “like butter,” making this a one-box answer for a serious metalworking shop or a dedicated home fabricator.

The recurring complaint is not the bits—it is how they are stored. The case is difficult to open fully, and one owner transferred the bits into an older, friendlier box. More importantly, the larger bits in this set come with full-sized shanks, meaning the 1/2 inch bit needs a 1/2 inch chuck, which most standard drills do not have; you will need a drill press or a chuck upgrade to use the biggest sizes. For anyone who wants the fullest fractional coverage in a single purchase, this is the definitive pick.