Best Cobalt Drill Bit Sets: Four Picks That Survived Our Metal-Drilling Tests

Introduction

A good set of drill bits is one of those workshop purchases that pays for itself the first time you need to drill through something hard. To separate marketing claims from real performance, fourteen drill bit sets ranging from about $13 to $180 were put through three punishing tests: a half-inch mild steel plate, a hardened spring steel leaf, and finally AR500 armor plating, which is about as hostile as materials get for a twist drill.

The results were surprising. Several of the cheapest sets beat the most expensive ones, and four brands in particular earned a clear edge on speed, durability, and overall finish. Here are the picks worth your money.

How the Testing Worked

Every set was run through the same controlled protocol. A 1-horsepower drill press delivered a consistent 130 pounds of downward force at 600 RPM for the mild steel test, with cutting oil applied to protect the bits. Timing was measured precisely, and each bit was examined afterward for wear to the cutting edges.

The spring steel stage increased the force to around 175 pounds at 340 RPM, and the survivors were re-tested on mild steel to measure how much speed each bit had lost. The final challenge was AR500 armor plating at roughly 220 pounds of force and 250 RPM. Few bits completed that test at all, which makes the ones that did stand out even more.

Best Overall Value: Kobalt Ware Cobalt Set

At $36 for a 29-piece set covering 1/16 to 1/2 inch, the Kobalt Ware bits claim M42 cobalt construction with a precise 135-degree split point, and they are designed for tough metals like stainless steel, cast iron, and high-temperature alloys, with the versatility to handle plastic and wood as well.

Across every stage, this was the standout. It drilled the half-inch mild steel plate in 19.65 seconds, edged out the more expensive DeWalt cobalt in the spring steel test at 21.79 seconds, and showed less than 1 percent speed loss across repeated passes, the best durability result of the entire field. In the final armor plating test, it shredded through AR500 in 58.69 seconds, the fastest of only four sets to finish at all. It held the best average finish of any brand tested, and it still looked nearly new afterward.

Fastest Performer: Milwaukee Cobalt Set

The Milwaukee set costs $65 for 15 bits in sizes from 1/16 to 3/8 inch. Instead of a standard split point, Milwaukee uses a quad edge tip made from cobalt alloy steel and claims 15 times the life of conventional bits.

It lived up to the speed claims. After a slight break-in period, it posted the fastest spring steel time of the field at 17.65 seconds and then got faster, becoming the quickest bit overall on repeat mild steel passes at 17.24 seconds. It defeated the AR500 plating in one minute and 17 seconds, the second set to do so, and retained plenty of cutting life afterward.

The main trade-off is coverage: the kit tops out at 3/8 inch and does not include a half-inch twist drill, which the cheaper Kobalt Ware set does include.

A Strong All-Rounder: Irwin Cobalt Set

The Irwin set costs $130 for 29 pieces in sizes 1/16 to 1/2 inch, made of M35 cobalt alloy steel with a 135-degree split point and designed specifically for hardened steel.

It was not the quickest bit on the mild steel plate at 23.55 seconds, but it consistently held up where others degraded. It drilled spring steel in 24.16 seconds and still looked nearly as good as new afterward, stayed in good condition through the second spring steel pass, and finished the AR500 armor test in 60.29 seconds, barely a second behind the winner. If you want a full-size 29-piece set that shrugs off hard metals, this is a very good choice.

Most Durable Pick: Viking Drill and Tool Set

At $180 for a 25-piece metric set covering 1 to 13 mm, the Viking bits are the most expensive in the field, made in the USA from M42 cobalt steel with a 135-degree split point.

Viking is not built for speed. It posted some of the slowest times through the mild steel plate, but durability is where it shines: it held up through every test stage with only about 8 percent speed loss and still looked in really good condition afterward. It was also the fourth and final brand to conquer the AR500 armor plating. If you drill hard metals regularly and want bits that keep their edge, this is a set you buy once.

Buying Advice

Budget matters less than you might think here. The best-performing set of the entire test cost under $40, while several sets priced well above $100 posted slower times and more tip wear. If you mostly drill wood, plastic, and occasional mild steel, a high-speed steel set like the affordable DeWalt bits is fine for light work, but they gave up quickly once the steel got hard.

If you drill stainless steel, spring steel, or anything hardened, stick with cobalt. M42 cobalt generally held up better than M35 in the repeated wear tests, though brittle M42 bits can chip if abused. Match the size range to your actual needs: if you need half-inch holes, check that the kit includes it, because some otherwise excellent sets stop at 3/8 inch.

Conclusion

The Kobalt Ware cobalt set earned the top spot by being fast, remarkably durable, and affordable all at once. The Milwaukee is the speed pick if your work stays under 3/8 inch, the Irwin is a strong full-size all-rounder for hardened steel, and the Viking is the buy-it-for-life durability option. Any of the four will handle hard metal far better than a basic high-speed steel set.