There is a unique frustration in watching a quality high-speed steel bit skate across a hardened lock face, leaving a shiny gouge and zero progress. The distinct screaming friction of a dull edge against hardened steel pins and a hardened bolt is a sound that signals wasted time and the wrong bit for the job. Navigating the options to find a bit that actually bites into a lock cylinder without snapping requires understanding the specific metallurgy and geometry that defines a true lock-drilling champion.
I’m Mo Maruf — the founder and writer behind The Tools Trunk. My research focuses on the chemical composition and cutting geometry of industrial drill bits, analyzing how material hardness ratings and point angles translate into real-world performance against hardened steel fasteners and lock bodies.
After analyzing five kits on the market, I have identified the most effective performers for destroying stubborn lock cores. This guide outlines the best drill bit for drilling out locks across mid-range and premium tiers, focusing on composition, heat management, and tip stability.
How To Choose The Best Drill Bit For Drilling Out Locks
The lock cylinder and its hardened retaining bolts demand a specific cutting tool. A standard general-purpose bit will either dull instantly or shatter under the torsion. The correct choice hinges on two primary factors: the base material of the bit and the geometry of its cutting tip.
Cobalt Content Is Non-Negotiable
Look for M35 cobalt steel, which contains a true 5% cobalt alloy. This additive allows the steel to retain its hardness at high temperatures generated by friction with hardened steel. Inferior bits labeled “cobalt” may use a thin coating rather than a full alloy, leading to rapid edge breakdown when encountering a lock’s hardened security pins.
Split Point Over Conventional Point
A conventional 118-degree point has a chisel edge that can cause the bit to drift on a convex lock face. A 135-degree split point features a self-centering web that engages immediately and resists walking. This eliminates the need for a center punch in many drilling out lock scenarios, providing a cleaner, faster entry into the core.
Left-Hand Bits and Extractor Sets
For extracting broken key remnants or removing a damaged bolt from the lock housing, a left-hand drill bit is essential. As it rotates counter-clockwise, it often grabs the broken fastener and unscrews it before a full hole is even drilled. These kits also include mating extractors that use a reverse spiral to bite into the hole.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| Sabre Tools 5/16″ Cobalt Bits | Cobalt Twist Bits | Clean core destruction | M35 Cobalt, 118° Pilot Point | Amazon |
| STROTON Cobalt Bit Set | Cobalt Twist Bits | Multi-size hard metal job | M35 5% Cobalt, 68 HRC, 135° Point | Amazon |
| REBRA Screw Extractor Set | Left-Hand Extractor Kit | Broken bolt extraction | Cobalt HSS Left-Hand Bits + Extractors | Amazon |
| DUNDOO Screw Extractor Set | Left-Hand Extractor Kit | Socket-driven extraction | Cr-Mo Steel + Cobalt HSS, Spline Shank | Amazon |
| PLATINUMEDGE Step Drill Bits | Step Bits | Thin metal panel drilling | HSS, Nitride Black, Double Flute | Amazon |
In‑Depth Reviews
1. Sabre Tools 5/16 Inch Cobalt Drill Bit Set
This set provides five identical 5/16-inch bits, a dedicated size ideal for destroying the pin tumblers and centering on most common lock cylinders. The M35 cobalt alloy ensures the cutting edges don’t anneal under the heat generated from drilling through hardened steel, and user reports confirm it cuts through hardened steel with minimal sharpness loss after a dozen holes.
The pilot point tip is a specific advantage for drilling out locks. Unlike a standard chisel point, this geometry grabs the steel immediately, preventing the bit from skating across the curved face of a lock cylinder. Using medium pressure with cutting oil and a slow speed allows the bit to chew through the material without generating excess heat that would ruin the temper of the bit.
The only minor complaint involves the storage case, which has a wonky latch and doesn’t allow the indexes to fold out smoothly. However, the bits themselves are described as well-made and true-to-size. For a focused, single-size solution for lock destruction, this is a precise and durable choice.
What works
- Pilot point tip prevents walking on curved lock faces.
- True M35 cobalt composition handles hardened steel heat.
- Bits retain sharpness after multiple uses in steel.
What doesn’t
- Only one bit size (5/16″) in the set.
- Plastic storage case has poor build quality.
2. STROTON Cobalt Drill Bit Set (13-Piece)
This kit spans 1/16-inch to 1/4-inch in 1/64-inch increments, providing the incremental sizing necessary to drill a pilot hole before stepping up to the final diameter for a lock bolt. The STROTON bits are manufactured from a verified 5% cobalt ore, giving them a surface hardness of 68 HRC that withstands the abrasive wear from hardened steel and cast iron lock components.
The 135-degree split point is another critical feature for this application. It self-centers aggressively, eliminating the need to file a flat spot on the lock face before drilling. Users drilling into hardened 10.9-grade bolts note that the bits cut effectively, but the cobalt material is inherently brittle and will snap if subjected to bending loads or lateral pressure.
The set includes a sturdy storage case, making it easy to keep the bits organized in a tool bag. For a technician who regularly encounters various sizes of damaged fasteners and lock bodies, the range of sizes combined with the high cobalt content delivers excellent longevity per hole, despite the bit’s sensitivity to alignment technique.
What works
- True 5% cobalt content with verified 68 HRC rating.
- 135° split point centers well on rounded surfaces.
- Full range of 13 sizes for progressive drilling.
What doesn’t
- Brittle bits require strict straight alignment.
- Will snap under lateral bending pressure.
3. REBRA Screw Extractor and Left-Hand Drill Bit Set
This 14-piece kit is specifically designed for the mission of removing broken bolts and stripped screws, which is often the final step in drilling out a lock. It includes six left-hand cobalt HSS drill bits and six alloy steel extractors in matching sizes. The left-hand rotation can seize a broken fastener and spin it out before a deep hole is even drilled.
The kit adds a quick-change magnetic adapter and a tungsten carbide scribing pen. The adapter helps maintain a stable connection between the bit and the driver, reducing the wobble that can snap a left-hand bit. The carbide pen is useful for scoring a starting point on the stubborn face of a hardened bolt, assisting the split-point bit in centering.
Quality control is a concern with this specific kit. While some customers report pulling stuck fasteners from cylinder heads with no issue, others report bits that fail to hold a center line or snap immediately. The margin of error is small, and the user must apply a consistent, straight feed pressure. For a budget-friendly entry into extraction, this kit works, but the user must be prepared for potential inconsistency.
What works
- Includes both left-hand bits and extractors in one case.
- Magnetic adapter helps reduce wobble.
- Carbide scribe aids in starting on hardened steel.
What doesn’t
- Bit quality inconsistent; some fail on first use.
- Small bevel on bits can cause them to drift.
4. DUNDOO 15-Piece Screw Extractor Set
This set distinguishes itself by combining Cr-Mo steel extractors with cobalt-fortified HSS left-hand drill bits. The Cr-Mo steel provides a tough, ductile base for the spiral extractors that won’t snap or chip under the heavy torque required to free a seized lock bolt. The bits include a multi-spline design that allows them to be driven with a socket wrench or standard driver.
The socket-driven format is a major advantage when working in tight automotive or cabinet lock environments where a drill chuck simply will not fit. Users have reported removing stuck compression adapters and security bolts from motorcycle ignitions in under 30 seconds using this kit. The high-density spiral on the extractors provides a strong bite into the pilot hole.
This is not a set for budget hunters; it represents a step up in cost and complexity. However, for a technician or serious DIYer who needs a reliable extraction system, the DUNDOO kit consistently performs. The only limitation is that no removal set can solve every broken fastener, especially those that require heat or penetrating oil as a first step. For those it does handle, it is exceptionally efficient.
What works
- Spline shank works with socket wrenches for tight access.
- Cr-Mo steel extractors are tough and resist snapping.
- Extremely fast removal on stuck fasteners.
What doesn’t
- Higher cost than entry-level extraction kits.
- Cannot free fasteners requiring heat or penetrating oil.
5. PLATINUMEDGE Step Drill Bits Set
While not designed for drilling through a solid lock cylinder, this step bit set is the ideal tool for the second stage of a lock-out: drilling through the thin metal panel of a padlock shackle or a door strike plate. The double-flute design allows swarf to escape rapidly, preventing binding in the cut. The 4241 HSS with nitride black coating maintains a sharp edge on sheet metals and aluminum.
The five bits cover 50 step sizes from 3/16-inch up to 1-3/8-inch. This versatility is perfect for creating clean, burr-free holes in thin material where a standard twist bit would tear or grab. The step geometry also allows for countersinking the head of a screw flush with the surface, which is useful after a lock has been removed and the hardware needs replacing.
These bits are not intended for deep penetration into hardened steel bolts. Attempting to use a step bit on a thick lock shackle will likely damage the cutting edges. However, for removing the physical mounting plate and soft metal components around a lock, this set offers precise, clean cuts far superior to any twist bit.
What works
- Double flute clears chips quickly from thin metal.
- 50 step sizes replace many individual twist bits.
- Nitride coating provides good lubricity for sheet metal.
What doesn’t
- Not suitable for drilling hardened lock steel.
- Step design is awkward on deep holes.
Hardware & Specs Guide
M35 Cobalt Steel (5% Cobalt)
This is the baseline alloy for drilling hardened steel. The cobalt addition raises the red-hardness of the steel, meaning the cutting edge retains its hardness even when friction heats the tip to over 1,000 degrees Fahrenheit. Cheaper HSS grades will soften and dull instantly on a lock bolt, while a true 5% cobalt bit will maintain its bite.
135-Degree Split Point
A split point geometry features a secondary grind across the chisel edge of the bit tip. This creates a self-centering cutting edge that engages the material immediately. A standard 118-degree point has a flat chisel that can walk. For drilling out locks where the surface is curved and smooth, a split point is not optional; it is mandatory for accuracy.
FAQ
Can I use a standard titanium drill bit to drill out a lock?
Why does my drill bit keep walking across the face of the lock?
When should I use a left-hand drill bit instead of a regular bit?
Final Thoughts: The Verdict
For most users, the drill bit for drilling out locks winner is the Sabre Tools 5/16 Inch Cobalt Set because its pilot point tip and M35 alloy are purpose-built to bite into a hardened lock cylinder without walking or dulling. If you need a range of sizes for progressive drilling into broken bolts, grab the STROTON Cobalt 13-Piece Set. And for reliable extraction of a broken fastener from a lock housing, nothing beats the socket-driven ease of the DUNDOO Screw Extractor Set.