4 Best Drill Bits For Drilling Out Locks | Hardened Cobalt Bits

Check Price on Amazon

The NordWolf set stands apart because every bit in the 14-piece range uses a 1/4-inch hex shank that locks into impact driver collets without slipping. When drilling into a lock cylinder’s hardened steel pins, the hex shank prevents the rotational slippage that round shanks often suffer, keeping the 135-degree split point exactly where you aim it. The M35 cobalt formulation maintains hardness through repeated cuts, which matters when you’re drilling multiple locks or removing several rusted bolts in a row.

The included sizes span from 1/16-inch up to 1/4-inch, which covers the typical diameters needed for lock cylinder shear line drilling and pilot holes for screw extractors. Each bit features a titanium finish that reduces friction and helps chip evacuation, though the real value lies in the cobalt content rather than the surface coating. The plastic storage case has an integrated clip for pegboard hanging and clearly marked sizes so you grab the right bit without squinting.

User feedback consistently highlights how these bits cut through thick steel and stainless without needing excessive downward pressure. The hex shank also works with standard keyless chucks, so you’re not locked into impact driver use only. The set is noticeably harder than typical hardware store bits; some users note that the smaller bits can snap if you push sideways, so maintaining straight drilling alignment is essential.

Check Price on Amazon

Left-hand drill bits are the secret weapon for anyone who has ever snapped a screw extractor inside a bolt and made the problem worse. This five-piece set from VALYRIANTOOL uses M35 cobalt steel with a reverse twist that rotates counterclockwise, so when you drill into a broken bolt or stripped screw, the left-hand torque often catches the remaining threads and spins the fastener right out. The stubby lengths — from 2-1/4 to 3-5/8 inches — let you work in tight spaces like door hinges, machine housings, or recessed lock faces where a full-length bit won’t fit.

The five imperial sizes cover the most common extraction diameters: 1/8, 5/32, 3/16, 1/4, and 19/64 inch. Each bit uses a 135-degree split point that self-centers on the uneven surface of a broken stub, reducing the risk of walking off the edge and damaging the surrounding threads. The compact plastic case imprints each size on the lid so you can identify the right bit instantly without fumbling through a drawer.

Real-world results from users show these bits drilling through stainless steel and hardened bolts within 30 seconds when used with slow, steady pressure. The M35 alloy runs harder than standard HSS left-hand bits, which tend to glaze over against high-Rc materials. One user reported the 1/8-inch bit snapping on a second screw, suggesting the smaller diameters are more brittle — something to watch for if you’re working with heavily rusted fasteners that require aggressive torque.

Check Price on Amazon

The WildBossy set delivers 20 cobalt bits from 1/16-inch up to 1/2-inch, covering the widest diameter range of any set in this roundup. That span matters when you need to drill a small pilot hole into a broken tap and then step up through larger diameters without switching to a different brand or material. The M35 cobalt formulation with 5% cobalt targets a Rockwell hardness around 67 HRC, which is enough to cut through lock cylinder pins, cast iron engine components, and titanium fasteners without overheating.

Each bit uses a 135-degree split point with a titanium surface and a three-flat shank design that grips the chuck tighter than a fully round shank. The three-flat pattern prevents spinning inside the jaws during heavy drilling, though it lacks the positive lock of a full hex shank used in impact drivers. The twist flute geometry is precision ground to evacuate chips efficiently, which prevents binding when drilling deep into a bolt head or lock housing.

User experiences are mixed but generally positive — many report drilling through stainless steel and broken taps “like butter” with proper technique, while others note that a few bits arrived dull or snapped on the first use. The variance suggests quality control may not be as tight as premium brands, but the price per bit is significantly lower than the NordWolf set. For someone who needs a broad range of cobalt bits for occasional lock drilling without breaking the budget, this set provides good coverage.

Check Price on Amazon

This kit combines seven HSS left-hand drill bits with seven spiral screw extractors and five multi-spline extractors, making it the most complete all-in-one solution for broken fastener removal. The left-hand bits drill a pilot hole while simultaneously loosening the bolt, and if the reverse torque doesn’t spin it out, you move to the spiral extractor which bites into the pilot hole and twists the remnant free. The extractors are made from CR-MO (chrome-molybdenum) steel, which is harder and tougher than the chrome vanadium used in budget extractor sets.

Bit sizes match common bolt diameters, and the extractors are color-coded or dimensionally marked to pair with the right pilot hole depth. The HSS construction on the drill bits is adequate for most lock and bolt applications, though it lacks the high-temperature edge retention of M35 cobalt — you may notice faster dulling if you’re drilling through multiple hardened lock pins in succession. The compact storage case keeps all 19 pieces organized with dedicated slots that prevent the extractors from rattling against each other.

Mechanics in rust-belt regions praise this set for surviving multiple extractions on frozen automotive bolts, with one user calling it a “gift from above” after it removed six stubborn fasteners. However, a critical failure report describes an extractor snapping inside an M10 bolt, turning a one-hour job into a much bigger repair. Using slow speed and steady pressure is essential — excessive impact force or fast RPM can cause the extractor to fracture, especially in brittle or case-hardened bolts.