Why Does My Key Spin in the Lock?

A key that turns and turns but does not move anything is one of the more alarming faults, because nothing about it feels fixable and it usually happens at the worst moment. The good news is that it is nearly always the lock rather than the door, and in most cases it is the cylinder rather than the whole lock.

What is actually happening

When you turn a key you are not moving the bolt directly. You are turning the barrel of the cylinder, which turns a small tongue of metal on the back of it called the cam, and the cam drives the lock. If the key spins freely, the connection between those parts has broken somewhere. The key is doing its job; nothing downstream is listening.

The three common causes

The cam on the back of the cylinder has sheared

This is the most common. The cam is a small part under a lot of strain every time the door is locked, and on a worn or poorly aligned door it takes more strain than it was meant to. When it goes, the key turns smoothly through 360 degrees and nothing moves at all. The cylinder has to be replaced; the rest of the lock is usually fine.

The cylinder retaining screw has worked loose

A euro cylinder is held in place by a single long screw through the edge of the door, below the cylinder. If that screw backs out, the whole cylinder can rotate in its housing, so the key turns and the cylinder turns with it. This is the one case that is genuinely worth checking yourself, and it is dealt with below.

The multipoint gearbox has failed

On a uPVC or composite door, the key turns the cylinder, the cylinder turns the cam, and the cam drives a gearbox that throws the hooks and rollers up and down the edge of the door. If that gearbox has failed, the key can feel almost normal but nothing engages. This is the more expensive of the three, and it is usually the end of a longer story: a door that had started to need lifting or leaning on before it would lock was forcing that gearbox every single time.

The first thing to do, and it matters

If the door is open, do not close it. A door you cannot lock is an inconvenience. A door you cannot unlock, with you on the outside, is a much worse afternoon. Prop it, stay with it, and get it looked at while it is open — the job is the same either way, and you are not locked out while it happens.

If the door is already shut and you are outside, stop turning the key. If part of the mechanism has sheared, working it repeatedly can shear the rest and turn a cylinder change into a bigger job.

Is the door actually locked?

Worth being clear about, because it catches people out. If the key spins, the door is very often not locked, even though it feels closed and the key has turned. On a multipoint door, the giveaway is that the handle lifts without resistance and the key turns without the usual firm stop. If you are leaving the property, assume it is unlocked until somebody has confirmed otherwise.

The one thing you can safely try

Open the door and look at the edge, below the cylinder. There should be a single screw head, usually a long machine screw running into the cylinder. If it is loose, or missing, that is very likely your answer. Tightening it gently may restore normal operation. Do not overtighten it — the screw threads into the cylinder itself, and a snapped screw in there is a worse problem than the one you started with.

If the screw is tight and the key still spins, it is one of the other two causes, and both need the cylinder or the gearbox out of the door.

What we do about it

We establish which of the three it is, which usually takes a couple of minutes with the door open. A sheared cam or a loose cylinder is a cylinder replacement, and it is worth fitting an anti-snap cylinder while the door is apart rather than putting back the standard one that came with it.

If it is the gearbox, a photograph of the strip down the edge of the door will usually tell us the make — but not the size. That can only be established with the gearbox out and measured, which is why we carry a large stock of the common ones in a range of sizes, so most jobs finish on the first visit rather than becoming a wait for parts.

No call-out fee, no fix no fee, and a price agreed before we set off. We work 7am to 7pm, seven days a week.