It happens in a heartbeat. You’re torquing down a fastener or trying to back out an old, rusted lag bolt, and then you feel that sickening pop. The tension vanishes. You look down, and the head of the screw is sitting in your socket or lying on the floor, leaving a jagged, flush-mounted stump buried deep in the material. It’s a gut-punch. Honestly, learning how to remove a sheared screw is less about brute force and more about physics, patience, and having a few specific tricks up your sleeve that most people overlook until they've already ruined the workpiece.
The panic usually sets in immediately. You think you have to drill the whole thing out and re-tap the hole, but that’s often the last resort. Most sheared screws fail because of over-torquing during installation or "hydrogen embrittlement" in high-strength bolts, but the most common culprit for DIYers is simple corrosion. When the shank is stuck, it’s basically cold-welded to the surrounding metal or wood. If you just grab a drill and start praying, you’re going to wander off-center and destroy the threads. Stop. Take a breath.
The First Rule of Extraction: Don't Make It Worse
Before you touch a tool, you need to assess the "stub." Is there any metal sticking out? Even a millimeter? If you can grab it with a pair of high-quality locking pliers—Vise-Grips are the industry standard for a reason—you might be home free. But don't just twist. Use a penetrant.
I’m not talking about WD-40. While WD-40 is a decent cleaner, you want a dedicated penetrant like PB Blaster or Liquid Wrench. Even better? Many professional machinists swear by a 50/50 mix of Automatic Transmission Fluid (ATF) and acetone. A 2007 study by Machinist's Workshop magazine actually found this homebrew mix to be significantly more effective at breaking the bond of rust than many commercial off-the-shelf sprays.
Spray it. Walk away. Wait at least twenty minutes. If you’re dealing with a sheared bolt on a car engine or an old deck, wait overnight.
Why Heat is Your Secret Weapon
Metal expands when it gets hot. When you heat the area around a sheared screw, the hole expands slightly faster than the screw itself. This microscopic movement is often enough to break the "bond" of the rust. Use a propane torch or a butane pencil torch to heat the surrounding casting—not the screw itself, if you can help it.
Be careful with aluminum. It doesn't change color before it melts, so you can accidentally turn your engine block into a puddle if you aren't paying attention. Once it's hot, touch a stick of paraffin wax or a candle to the threads. The wax wicks into the threads, acting as a high-temp lubricant. It sounds like old-timer magic, but it works because of capillary action.
How to Remove a Sheared Screw Using Left-Hand Bits
If the screw is flush, your best friend is a left-hand drill bit. Most people don't even know these exist. They look like regular bits, but the flutes run in the opposite direction.
Here’s why they’re brilliant: as you drill into the screw to create a pilot hole for an extractor, the friction and heat of the bit are trying to turn the screw counter-clockwise. Frequently, the vibration and the "bite" of the left-hand bit will simply catch the screw and back it right out while you're drilling. You kill two birds with one stone.
💡 You might also like: Why Guys With Curly Brown Hair Struggle With Their Texture (And How To Fix It)
- Center Punching is Non-Negotiable. Use an automatic center punch to create a divot exactly in the center of the sheared shank. If you start drilling off-center, you’ll hit the threads of the hole, and then you’re looking at a much more expensive repair involving Helicoils.
- Slow and Steady. Use a low speed. High speed creates heat that hardens the screw (work-hardening), making it nearly impossible to drill through.
- Pressure. Lean into it. You want the bit to "bite" and peel out ribbons of metal, not just spin and smoke.
The Extractor Dilemma (Spiral vs. Straight)
If the left-hand bit didn't back it out, you need a dedicated extractor. There are two main types: the spiral "easy-out" and the straight-fluted extractor.
Spiral extractors are tapered. This is a double-edged sword. As you twist them in, they dig deeper, but they also apply outward pressure. On a thin-walled casting, that outward pressure can actually wedge the screw tighter into the hole or, worse, crack the housing. Straight-fluted extractors (like those made by Ridgid or Snap-on) are generally safer because they don't expand the screw as much. They bite into the sides of the pilot hole and provide a solid mechanical grip.
If you snap an extractor inside the screw, you are in a world of hurt. Extractors are made of hardened tool steel. You cannot drill through them with standard bits. You’d need a solid carbide burr and a very steady hand. Avoid this nightmare by never using a "cheater bar" on an extractor. If it doesn't move with moderate hand pressure, go back to the heat and penetrant.
The "Welded Nut" Technique
This is the nuclear option, and honestly, it’s the most effective method used in professional shops. If you have access to a MIG welder, you can often remove even the most stubborn sheared screw in minutes.
Basically, you find a nut with an inner diameter slightly smaller than the screw shank. Place the nut over the sheared stump. Aim your welder right into the center of the nut and "puddle" the weld onto the screw, filling the nut up. The intense, localized heat from the welder breaks the rust bond instantly. Plus, you now have a fresh hex head (the nut) to put a wrench on. Let it cool slightly—not all the way, but enough for the weld to solidify—and then gently work it back and forth. It works almost every time.
When Wood Screws Shear Off
Removing a sheared screw from wood is a different beast entirely. You can’t exactly take a torch to your mahogany table. Usually, these shear because someone didn't drill a large enough pilot hole or they used a cheap zinc screw in a hardwood like oak or ipe.
If the screw is deep, your best bet is a hollow screw extractor. It’s essentially a tiny hole saw. You drill around the screw, removing a small plug of wood with the screw inside it. Then, you glue in a wooden plug (a dowel), let it dry, and start your hole over again. It’s a bit of surgery, but it’s cleaner than gouging the wood with pliers.
Common Misconceptions and Mistakes
A lot of people think they can use a Dremel to cut a slot in the top of a sheared screw and use a flathead screwdriver. This rarely works for "sheared" screws because the very reason the head snapped off was that the screw was too tight to turn. If a high-torque hex head snapped, a tiny flathead slot definitely isn't going to have the leverage to move it. You’ll just strip the slot.
Another mistake is using the wrong size drill bit. If your pilot hole is too big, the extractor walls will be too thin and the screw will expand and lock into the threads. If the hole is too small, the extractor won't get enough "meat" to grab and will just chew up the inside of the screw. Follow the sizing chart that comes with your extractor set religiously.
Advanced Recovery: The Tap and Die Set
Let’s say the worst happens. You’ve mangled the threads. Or maybe you had to drill the screw out entirely because it was a Grade 8 bolt that laughed at your extractors. You aren't defeated yet.
🔗 Read more: When Will It Snow in Utah: What Most People Get Wrong About the 2026 Forecast
You have two real paths here:
- Chasing the Threads: If the damage is minor, use a "thread chaser" or a tap to clean out the old threads. This isn't the same as cutting new threads; you're just trying to push the metal back into its original shape.
- Over-drilling and Tapping: If the hole is wallowed out, drill it to the next standard size and tap new, larger threads. This requires a larger bolt, which might not always fit your application.
- The Helicoil/Time-Sert: These are stainless steel thread inserts. You drill the hole larger, tap it with a special size, and screw in a coil that restores the original internal thread size. These are actually stronger than the original threads in materials like aluminum.
Actionable Steps for Success
To get that screw out without losing your cool, follow this specific progression. Don't skip steps.
- Clean the area: Use a wire brush to see exactly what you're working with. If there’s grease, hit it with brake cleaner.
- Apply Chemical Persuasion: Use a high-quality penetrant. Give it time. This is the hardest part for most people.
- Shock the screw: Hit the end of the sheared shank with a hammer and a punch. The vibration can help "crack" the bond of the oxidation.
- Use Heat: If the material allows, use a torch. Expand the surrounding area, not the bolt.
- Drill with Left-Hand Bits: Start small and work your way up. Keep the drill perfectly straight.
- Engage the Extractor: Use a tap handle, not a wrench, to ensure you are applying even, downward pressure without side-loading the tool.
- Know when to quit: If it’s not moving and you’re starting to feel the tool flex, stop. More heat, more oil, or call a local machine shop. They usually have EDM (Electrical Discharge Machining) tools that can disintegrate a broken bolt without touching the threads.
Dealing with a sheared screw is basically a rite of passage in the mechanical world. It’s frustrating, sure, but once you’ve successfully extracted a few using these methods, that "pop" of a head snapping off becomes a manageable problem rather than a project-ending disaster. Keep your bits sharp, your torch full, and your patience high.