Two jobs with different purposes.
Rekeying changes a compatible lock cylinder's internal keying so it operates with a different key. The serviceable lock hardware generally remains in place. Replacing a lock means changing the cylinder, lockset, or other hardware, depending on the scope of the job.
For someone learning the trade, the useful question is not which option is always better. It is what problem needs to be solved: control over existing keys, a hardware fault, compatibility, or a change in function.
| Question | Rekeying | Replacement |
|---|---|---|
| What changes? | The cylinder's keying and the key that operates it. | The selected cylinder or hardware. |
| When might it fit? | Existing hardware is suitable and serviceable, but key access needs to change. | Hardware is damaged, unsuitable, incompatible, or needs a different function. |
| What needs checking? | Cylinder type, condition, key compatibility, and the complete keying arrangement. | Door preparation, dimensions, function, compatibility, and applicable requirements. |
Start with the customer's concern.
Someone moving into a home may want control over who has working keys. Someone with a sticking latch may have a mechanical or alignment problem. Those are different concerns, even if both begin with “I need new locks.” Ask what has changed and what result the customer expects.
Do not confuse key control with repair.
Changing the keying does not by itself fix worn hardware, a misaligned door, or an unsuitable lock function. Likewise, changing a lock without reviewing the rest of the opening may leave the original problem unresolved. An inspection should guide the recommendation.
Compatibility matters.
Making several locks work with one key depends on compatible hardware and the intended keying arrangement. Matching the brand name or appearance alone is not a complete compatibility check. Identify the actual products and consult the manufacturer's documentation.
What should a learner practice?
Practice explaining the difference in plain language. Given training hardware, identify the parts and describe what a rekeying task would change. Under an instructor's guidance, learn the relevant servicing and checking procedure for that particular cylinder.
After authorized work, the agreed keys and relevant lock functions need to be checked. In more complex key systems, the intended behavior must be documented and reviewed by someone qualified to manage that system.
The takeaway: first identify the access goal and the hardware condition. Then decide which work addresses both.