- Use a follower and keep constant contact so no top pin drops into the plug.
- Test four times. Cylinder alone, installed, door open, door closed.
- Keying several doors alike removes the reason people prop a door open.
- Tool rekeyable cylinders use sliding wafers, so conventional picking and pinning do not apply.
The procedure
Remove the cylinder, retain the plug with a follower so the top pins and springs stay in the housing, and slide the plug out. Tip the old bottom pins out, insert the new key, and fit the bottom pin that brings each stack level with the top of the plug. Slide the plug back in behind the follower, keeping constant contact so no top pin drops into the plug, and reassemble.
Test before the door closes. Turn the new key several times in both directions in the cylinder alone, then in the installed lock, then with the door open, then with the door closed. Four tests, in that order. Skipping the last one is how a customer ends up locked out by the lock you just serviced.
Count your pins in and out. A pin left on the bench is a pin that is not in the lock, and a five pin lock running on four is a lock that opens to far more keys than it should.
When rekeying is the right answer
New house, lost key, ended tenancy, ended relationship, contractor finished, cleaner left, key given out years ago and never returned. In all of these the hardware is fine. Only the key list is wrong. Rekeying solves it for the price of a few pins.
Rekeying also lets you key several locks alike. A house with a front deadbolt, a back door knob and a garage entry on three different keys is a house where somebody props a door. One key on all three is both more convenient and more secure, and it is a quick upsell that customers genuinely thank you for.
Replace rather than rekey when the hardware is failing, when the grade is inadequate for the door, or when the keyway is so common that key control is impossible. Say which of those applies and why. A customer who understands the reason accepts the higher price.
Smart keyed and tool rekeyable cylinders
Kwikset SmartKey and similar systems let a homeowner rekey without disassembly. Insert the working key, turn a quarter, insert a small tool, remove the old key, insert the new key, turn back. The cylinder learns the new key.
These use a sliding wafer mechanism rather than a conventional pin stack, so standard picking does not apply and standard rekeying does not either. They also have their own failure modes. Forcing the mechanism or losing the reset sequence can lock the cylinder into a state that requires replacement.
Know how to reset them, carry the tools, and be honest about their security. They resist picking well and they are convenient. Early versions had documented bypass weaknesses. For a customer whose main concern is a departed tenant they are entirely sensible. For a customer with a genuine targeted threat, sell a higher grade cylinder.
Common Questions
Is rekeying as secure as buying a new lock?
Yes, if the lock is sound. Rekeying changes which key turns it. It does nothing about a weak bolt, a soft frame or a short strike screw, and those are what actually get kicked in.
Can all my locks be put on one key?
Usually, as long as they share a keyway or can be swapped to one. It is the most common request after somebody moves house and it is quick work.
How soon should I rekey after moving in?
Before you sleep there. You have no way of knowing how many keys the previous owner handed out, and agents, contractors and neighbors all tend to have one.