Most people have experienced broken keys at some point and it is one of the most infuriating problems you can have with a lock. The reason behind this is not always clear but generally happens for a couple of reasons.
One reason might be that the key is old and has started to weaken, this may be in the form of a fracture which are sometimes visible to the naked eye or simply the metal becoming weak and more pliable. The causes for this might simply be age, misuse in the form of continually bending the key when putting it in and out of the lock or maybe you constantly sit on them just to mention a couple.
Another reason might be that the cylinder or mortice lock has developed a fault and each time the key is turned it is straining, thus at some point it is going to break. This is normally obvious and as soon as you feel it is straining, then the cylinder or lock should be checked before it is too late.
In mortice locks if a piece of the key breaks off within the lock it normally causes the lock to seize up and the result is a replacement lock. However, in the case of cylinders, sometimes we are able to remove the piece of key and if the lock is still working correctly we do not have to replace it.
This happened today for our customers at Gonwin Manor in Carbis Bay. We attended the site to find that the bow of the key (the piece you hold) had come away leaving the rest of the key buried deep inside the euro cylinder core.
We managed to remove the remaining piece of key but Steve requested that the cylinder still be changed even though it was still working correctly. As Steve said, because this is a holiday cottage, he would rather change the cylinder than have this happen again to another customer.
You can try to prevent this sort of problem happening fairly easily, 1 .. should you find that the key is not turning smoothly, then it is best to call a professional before there are other problems developing. 2 .. check your keys regularly and if there are any signs of a stress or fault, get them changed sooner rather than later.
If you find that your key breaks in the lock, do not try to remove it yourself. This may either damage the face of the cylinder or push the broken piece of key deeper into the lock. This might prevent us from getting it out and then we may not be able to save the cylinder for you.