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Why screws break—and why drilling straight matters
A broken screw is easiest to remove before you enlarge the hole or damage the surrounding material. The usual causes are rust, overtightening, a worn or mismatched driver bit, or a screw driven into a hard material without a pilot hole. Once the head snaps off, the goal is to drill through the screw’s center while keeping the bit away from the workpiece.
This job needs control more than power. Use a cordless drill in its low-speed range; don’t use an impact driver, which can twist a small bit, wander off center, or snap it. A hammer drill’s hammer mode is also unsuitable. Turn both features off and clamp the workpiece if you can.
Choose the approach before you drill
First check whether any of the screw’s shank is exposed. If it is, locking pliers may remove it without drilling. Grip the shank close to the workpiece and turn slowly counterclockwise. For a flush or recessed break, drilling may be necessary. If the screw is in a delicate, valuable, or load-bearing part, stop if the bit begins to wander; a repair shop may cost less than repairing the damage.
Identify the screw’s material and approximate diameter. Hardened screws and stainless steel can be harder to drill than ordinary steel. A small, sharp bit and light pressure are safer than a large bit forced through the fastener. Keep the bit centered on the screw, not on the original pilot hole if that hole is off-center.
Tools and bits: what to buy
A basic setup is a variable-speed cordless drill, sharp metal-cutting bits, a center punch, and eye protection. A cobalt bit costs more than a general-purpose bit but can hold up better in hard metals; for one small screw in soft wood, a standard sharp bit may be enough. If you need a set, compare cobalt drill bit sets by size range and whether the smallest bits are included.
Left-hand drill bits rotate counterclockwise and sometimes back a screw out as they cut. They are worth trying before an extractor, but they do not guarantee removal. A screw extractor can work when the pilot hole is centered and the screw is not seized; too much torque can break the extractor, which is hardened and difficult to drill out. A left-hand bit and screw extractor set is convenient for occasional repairs, but a cheap set is not a substitute for careful alignment.
Which bit should you try?
| Bit or tool | Best use | Main drawback |
|---|---|---|
| Standard HSS bit | Soft steel screws and occasional jobs | Can dull quickly on hardened fasteners |
| Cobalt bit | Harder steel and repeated metal drilling | Costs more; still breaks if bent or overheated |
| Left-hand bit | Centered pilot holes; may unscrew the fastener | May cut without loosening the screw |
| Screw extractor | Gripping a drilled pilot hole in a stuck screw | Can snap if forced or used off-center |
Drill a centered pilot hole
Mark the center of the exposed screw with a center punch. A light tap is enough; a heavy blow can shift the screw or dent the workpiece. If you can’t use a punch, start with the smallest bit you have and steady the drill carefully. For a screw around 4–5 mm in diameter, a pilot bit roughly 1.5–2 mm is a practical starting point, provided it fits within the screw’s core.
Set the drill to low speed and keep it square to the surface. Start gently, using short bursts and light pressure. Let the bit cut rather than leaning on it. If it squeals, stops cutting, or becomes too hot to touch, stop and let it cool; forcing a hot bit can dull it or snap it. A drop of cutting oil can help when drilling metal, but keep oil away from finishes or materials it may stain.
Drill only as deep as the screw body requires for the next step. Use tape on the bit as a depth marker, or a drill stop, so you don’t plunge into the material beneath it. If the screw is in wood, this matters especially: once the bit exits the metal, it can rapidly bore into the surrounding hole and leave a larger repair.
Back the screw out—or drill it away
If a left-hand bit catches, keep the drill turning counterclockwise and let it work; the screw may turn out with it. If not, switch to an extractor only if the pilot hole matches the extractor’s instructions. Turn it slowly by hand with a tap wrench or small handle where possible. Do not use an impact driver or apply a sudden burst of torque. If the extractor starts to twist without moving the screw, stop.
If extraction fails, the remaining option is to drill through the screw with a bit just smaller than its outer diameter, then remove the thin remnants with a pick or pliers. This often sacrifices the original threads. In wood, you may need a plug or a larger replacement fastener; in metal, the hole may need re-tapping or a threaded insert. If keeping the original hole size is essential, drilling out the fastener is not a risk-free fix.
Protect the surrounding material
Use masking tape around the screw to protect a finished surface and make the bit’s position easier to see. Clamp small parts securely, and place a scrap board behind thin sheet material to reduce breakout. Keep the drill perpendicular: a tilted bit can cut into the workpiece even when the pilot hole starts centered. Wear eye protection, since small bits and metal chips can break or fly.
Stop if the bit skates, bends, or begins cutting the workpiece. Re-center with a punch or switch to a smaller, sharp bit rather than trying to correct the angle with sideways pressure. For one soft-metal screw, careful work with a basic bit is usually enough. For hardened screws, repeated jobs, or a valuable workpiece, better bits and a slower, more controlled approach are cheaper than repairing an enlarged hole.