Tracer

The tracer is the part of a key cutting machine that runs along the profile of the original key so that the cutter reproduces it on the new key. It is aligned with the cutter: whatever the tracer touches on the original, the cutter cuts on the copy.

Accuracy depends on its condition and its adjustment. A worn or badly calibrated tracer produces copies that go in but are hard to turn, or that work for a while and then fail. That is why a copy of a copy, or of a badly worn key, usually comes out worse than the original.

We do not cut copies of keys. But if a copy is hard to turn, do not force it: it is one of the most common causes of a key snapping inside the cylinder. If that has already happened to you, see broken key extraction.