Our readers keep the lights on and my morning glass full of iced black tea. As an Amazon Associate, I earn from qualifying purchases.5 Best Drill Bits For Drilling Out Bolts | Cobalt Bits Cut Out

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This kit combines left-hand drill bits with spiral and multi-spline extractors, which is the correct approach for a snapped bolt: a reverse-spinning bit that can back out the broken piece before you even need the extractor. The extractors themselves are made from CR-MO (chromium-molybdenum) alloy, which is noticeably harder than the chrome vanadium steel found in budget sets and resists twisting off inside the bolt.

Seven HSS left-hand drill bits with titanium coating handle the initial drilling, and the five multi-spline extractors provide a second tactical option for bolts that refuse to back out with the spiral style. The 19-piece count means you have size-matched pairs for nearly all common bolt diameters from small machine screws up to M10 fasteners. A durable storage case keeps each component in its own slot, reducing the chance of grabbing the wrong size mid-job.

Real-world feedback shows this set has successfully extracted five to six stubborn bolts in a single session, confirming that the CR-MO alloy and left-hand bit strategy work. However, a small number of users report that applying excessive torque can cause an extractor to snap, which is true for any extraction tool. Maintaining slow, steady speed and using cutting oil is the correct procedure here.

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M35 cobalt steel is the defining material for drilling out bolts because the 5% cobalt content allows the bit to maintain hardness even when friction against hardened bolt steel generates significant heat. This set covers 20 sizes from 1/16-inch to 1/2-inch, which includes the range you need for most automotive and machinery bolt removal. The 135° split point geometry digs in immediately and prevents the bit from skating across the rounded face of a broken bolt.

The titanium surface coating adds an extra layer of heat resistance and reduces friction during the cut, while the three-flat shank design eliminates slipping inside the drill chuck under high torque. Precision grinding along the full length ensures smooth chip evacuation through the flutes, which matters when you are drilling deep into a bolt that is flush with a surface. The plastic index case keeps each bit organized, though the case itself is basic.

Users drilling through snapped-off taps and studs in turbo housings report these bits cut “like butter,” which is the experience you want when every millimeter of drilling risks breaking the bit. A small number of units arrived with one or two dull bits, so inspecting the set immediately upon arrival is recommended. For the price-to-performance ratio in a cobalt jobber set, this is a strong contender.

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Step bits are not the primary tool for drilling out a broken bolt, but they excel at enlarging a pilot hole to the size needed for an extractor or a tap. This three-piece set covers a wide range: bit #1 spans 1/4- to 1/2-inch steps, bit #2 offers fine increments in the same range, and bit #3 reaches up to 7/8-inch. The M35 cobalt construction and TiAlN coating give these bits the heat resistance to survive cutting through hardened bolt material without losing their edge.

The 1/4-inch hex shank eliminates cam-out in impact drivers and quick-change chucks, and the 118° X-type openings with spiral flutes clear chips efficiently while deburring the hole edge as you go. This is particularly useful when you need a clean, round hole for a threaded insert after extraction. The included box keeps the three bits organized, though it is basic and not job-site rugged.

HVAC professionals and guitar amp builders report these bits cut through steel easily, with the TiAlN coating maintaining sharpness across 20-plus uses on hard material. One user noted that the penultimate step on the largest bit lost edge sharpness after repeated heavy use, which is expected for any step bit under sustained high-load drilling. Always use cutting oil with step bits to manage heat and extend life.

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Hex shank drill bits are purpose-designed for impact drivers, which deliver the high-torque, high-impact pulses that can snap straight-shank bits in a standard chuck. This HIGHFIRE set includes 22 HSS bits with a fully hardened hex shank that transmits torque without spinning, making it a solid choice for drilling pilot holes in bolts before an extractor is used. The 135° split point ensures clean starts on rounded bolt heads.

The titanium nitride coating extends bit life by roughly three times compared to uncoated HSS, and the tapered web design adds strength at the point where most bits break during high-torque jobs. The double blister pack is not a storage case; you will need your own organizer, which is a trade-off for the low pack size. Sizes run from 1/16-inch up to 1/2-inch, covering nearly every bolt diameter you will encounter in automotive and construction work.

Users running these in DeWalt impact drivers report solid performance through wood and soft metal, but the HSS material limits their suitability for hardened bolt steel. For drilling out a seized bolt, these are best used as pilot drills before stepping up to a cobalt bit or extractor. User feedback confirms they hold up well under normal drilling conditions without chipping, and the hex shank stays locked in quick-change chucks.

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This 21-piece set from Yougfin is built around M35 high-speed steel with 5% cobalt, placing it in the same material tier as the premium WildBossy set but with a gold oxide finish instead of titanium. Gold oxide is a surface treatment that provides a degree of corrosion resistance and helps identify wear, but it does not add the same heat barrier as TiAlN or TiN coatings. The 135° split point geometry is present, meaning these bits will self-center on a broken bolt face without walking.

The sizes run from 1/16-inch to 3/8-inch in 1/64-inch increments, which is a finer range than many sets and allows you to match the pilot hole precisely to an extractor size. The dual-flute design and precision-ground margins ensure smooth chip removal and accurate hole diameter. The index case is a strong point here — users consistently note that it keeps bits organized and protected, unlike some competitors that ship in basic blister packs.

Users drilling into stainless steel report that these bits stay sharp and cut cleanly when used with slow speeds and cutting oil. The case is the only recurring weak point, with some units arriving with hinge damage or cracking after repeated use. For the price point, the combination of M35 cobalt, a full index case, and fine size increments makes this a well-rounded option for anyone who needs a dedicated set for bolt drilling.