10 Best M42 Cobalt Drill Bits in 2026

A 29-piece set covering 1/16″ to 1/2″ in 1/64″ increments gives you a comprehensive range for precision metalwork. The M42 cobalt composition, built to Aerospace Standard 907, is the key. It allows for speeds up to 30% faster than standard M2 steel and delivers the high red hardness needed for stainless steel and titanium. This set is for the serious hobbyist or professional who regularly tackles hardened materials and needs a bit that will stay sharper, longer. The gold oxide finish isn’t just for looks; it acts as a built-in lubricant to manage heat and extend bit life.

One consideration is the round case, which makes every bit immediately accessible but occupies more space on a workbench than a flat index. According to expert comparisons, working with this set was nearly identical to using an Irwin cobalt set, but the Drill America bits remained sharper after the initial test holes. Those comparisons also note that sharpening took slightly longer, though the split point design helped align them easily on a grinder. For anyone regularly drilling hardened alloys, this combination of durability and a complete size range sets a high standard.

An 8% cobalt M42 alloy gives these bits ten times the life of standard bits, making them a durable choice for punching through stainless steel and cast iron without frequent replacements. For the metalworker or serious DIYer who drills a variety of hole sizes, the range from 1/16-inch up to 1/2-inch covers most common tasks. The thick web-helix design isn’t just marketing, it adds the rigidity needed when you’re leaning into a tough piece of titanium or thick steel plate.

You get a solid core set here, but it’s not the most comprehensive. If your work demands every 64th-inch increment, a fuller selection is available in the 29-piece Drill America set. Research and owner feedback suggest that quality control can be a roll of the dice with any brand’s cobalt bits, Bosch included. Still, for the price jump over a basic 10-piece set, the Bosch delivers a notably wider size range and the sturdy M42 material. This combination makes it the practical choice for value-focused buyers.

The tri-flat shank is the star here. Those three flat sides grip your drill chuck with absolute authority, eliminating the frustrating spin and slippage that can ruin a workpiece or your knuckles. For anyone regularly driving larger bits into tough metals, that mechanical lock is a genuine relief. Combined with the 135-degree split point that starts drilling exactly where you aim it, this set from Drill Hog is built for precise, demanding metalwork. It’s a solid choice for fabricators and serious DIYers who value control and durability over a flashy package.

Every major M42 cobalt bit brand, from Irwin to Bosch and even Drill Hog, has some one-star reviews from users reporting poor performance, according to research. This serves as a reminder that manufacturing variances exist, so even a well-regarded set might occasionally disappoint. For example, a boatbuilder found these Drill Hog bits excellent for drilling hard 316L stainless steel plate, noting they stayed sharp enough to shave with after several holes.

An M42 8% cobalt construction gives these bits the hardness and heat resistance to tackle stainless steel and hardened metals without immediately dulling. That makes this 19-piece Stroton set the logical pick for anyone working in a metric shop or on imported machinery, where the 1mm to 10mm range in half-millimeter increments covers most precise drilling tasks. Its split point geometry starts cuts quickly and helps prevent walking on curved surfaces.

The premium M42 cobalt blend offers long life and can run three to five times faster than some bits, but it is also more brittle than M35 cobalt. This means the bits are less forgiving in a wobbly handheld drill and perform best in a rigid setup like a drill press. For handheld use on hard materials, expert feedback indicates M35 cobalt bits are a more forgiving choice.

Expert testing selected these M42 cobalt bits as the best for hardened metal and stainless steel, which means they are built for drilling tough alloys. This 60-piece screw machine set covers wire gauge sizes from #1 to #60, a specialized range for precision tasks like tapping specific holes. The stub length is shorter than a standard jobber bit, providing more rigidity and less deflection, a critical advantage in tight spaces or on sensitive machinery. Made with added cobalt for cutting harder metals, the spiral flutes evacuate chips upward to reduce clogging when run counterclockwise. Everything comes in a metal case, keeping a complete selection organized and at hand.

The trade-off is in the specialized sizing and shorter flute length. For common fractional-inch sizes in general shop work, the Drill America D/A Series M42 Cobalt Jobber Drill Bit Set might be more practical. Research and owner feedback indicate that, like all major brands, experiences can vary. The consensus from expert testing is that Drill America’s M42 bits hold an edge well, remaining noticeably sharper after the first three test holes in multiple materials compared to some peers.

The 1/16″ to 1/2″ range in 1/64th increments means you’ll have the exact bit for tapping, clearance, or pilot holes without compromise. For the metal fabricator or serious machinist who regularly works with stainless or hardened alloys, this completeness is a major time-saver. The M42+ cobalt composition is the key, offering the heat resistance that keeps an edge through tough plate. It’s the set you buy when you’re tired of burning up bits and want a comprehensive, shop-ready solution for demanding materials.

You get a sturdy system here. The split point starts cleanly without a center punch, and the triple-flat shank grips solidly in any chuck, eliminating that frustrating spin-out. However, the 29-piece set in its steel case is a shop tool, not a portable kit for light duty. For a more compact, general-purpose M42 set, the Bosch CO14B offers a smaller selection of the most common sizes. The Drill Hog set’s value is in its unmatched granularity for precise work, making it a cornerstone for a busy metal shop.

An 8% cobalt M42 alloy hardened to HRC66 makes this set a specialist for tough jobs. It’s engineered to bite into hardened steel and cast iron where standard bits would dull quickly. The fully ground 135-degree split point is the key feature here; it grabs the material instantly so you can drill without a pilot hole and with less pressure. This set is built for the mechanic or fabricator who regularly encounters hardened fasteners or needs to drill consistent, clean holes in tough metals.

You pay for that capability with significant heft and size. The round case is sturdy but large, and the bits themselves are standard jobber length. That’s perfect for most bench work, but if you need to drill deep into a structural member, you’ll hit the chuck before you hit depth. For a more compact, workshop-focused alternative with similar metallurgy, compare the dimensions of the Bosch CO14B set. The MaxTool set justifies its bulk by delivering a complete fractional range that stays sharp under punishing use.

Formulated with 8% cobalt M42 steel specifically for hardened materials, this drill bit set maintains its edge when cutting through tough metals like stainless steel and cast iron. That composition makes it a logical choice for a fabricator or mechanic who regularly encounters tough alloys. Its split point geometry starts cuts cleanly on curved or hard surfaces, and the gold oxide finish aids in clearing chips and particles faster. If your workbench sees a steady diet of stainless or hardened steel, these bits are built for that abuse.

You trade some versatility for that focused performance. The selection is 14 common fractional sizes, so you won’t find the finer 64th-inch increments offered in sets like the 29-piece Drill America D/A Series. That’s a fair compromise, keeping the kit compact and cost-effective for its intended use. For drilling softer materials or needing every conceivable size, a larger set makes sense, but for dedicated work on hardened material, this COMOWARE set concentrates on the essentials.

Six identical 6mm bits made from 8% cobalt M42 steel make this pack a specialist’s stockpile. That specific cobalt formulation and titanium nitride coating are built for repeated drilling into stainless steel and other tough metals, offering serious wear resistance and heat tolerance. This pack is for the professional or advanced DIYer who burns through this particular size on demanding metalworking jobs and needs a ready supply on the bench.

The clear trade-off is versatility. You get depth in one size, not a range. If your projects require drilling holes from 1/16-inch to 1/2-inch, a comprehensive 29-piece set is the practical starting point. The PATIKIL pack then becomes a logical supplement for when you inevitably wear out your most-used size in that tougher material.

The triple-edge cutter head on sizes 3mm and up defines this set. This geometry bites into hard materials like 304 stainless steel, reducing the tendency for the bit to skate or walk. Combined with the split point design, it aims to make drilling easier with no slipping, which can improve control when starting a hole in tough metals.

The trade-off is the metric-only sizing, which might frustrate someone working primarily with imperial-dimensioned hardware or following American plans. If you need a mix of fractional and metric sizes, the Drill America D/A Series offers that flexibility. However, for pure metric work, the EdvenA set’s triple-edge design provides a tangible mechanical advantage in starting and cutting through stubborn materials that a standard two-flute bit just can’t match.