The copy-of-a-copy problem
A traditional duplicating machine works by tracing. A stylus follows the profile of your existing key while a cutter mirrors that movement into a blank. It is a mechanical analogue process, and like every analogue copy it inherits the original's flaws and adds a little of its own.
The tolerances involved are small. A residential pin tumbler cylinder expects each cut to be within a few thousandths of an inch of its nominal depth. A tracing machine with a slightly worn stylus, a cutter that has lost its edge, or a jaw that grips the blank a fraction off square will produce a key that is within tolerance but not centred in it.
Copy that copy and the error compounds. By the third generation the cuts can be far enough off nominal that the key works in a fresh lock and fails in a worn one, or works in the door but not the deadbolt because those two cylinders have aged differently.
This is why the key that “used to work fine” gradually stops. Nothing dramatic happened. A chain of small errors reached the end of its budget.
Cutting to code: the fix for drift
Every key has an underlying specification: a series of numbers describing the depth of each cut, and a keyway profile describing the shape of the blade's grooves. Together those are the key code.
Cutting to code means setting a machine to those nominal depths and cutting a fresh key from the specification rather than from an existing physical key. The result is a key at the centre of tolerance rather than wherever the last copy landed. It is measurably better and it stops the drift.
Where does the code come from? Sometimes it is stamped on the original key or on the lock. For a vehicle it may be obtainable through a verified channel with proof of ownership. For a residential lock, a locksmith can decode the cylinder directly — reading the actual pin heights and calculating the code from the lock rather than from the key.
Decoding is the right answer when every existing key is worn. Copying the best of a bad set preserves the wear; decoding the lock produces the key the lock actually wants.
It is worth writing your key code down somewhere safe once you have it. It is far easier to have a key made from a code than from nothing.
Blanks: why the right blank is not a detail
A blank is the uncut key, and the grooves running along its blade — the keyway profile — determine whether it will enter a given lock at all. Manufacturers use profiles partly for engineering reasons and partly to control which blanks fit which locks.
A blank that is close but not correct causes trouble that looks like something else. It may enter stiffly and wear the keyway. It may not seat fully, so the last pin is not lifted properly and the key fails intermittently. It may bind under rotation and put load on the plug.
Blank quality varies as well. Aftermarket blanks are often perfectly good and sometimes are made of a softer alloy that wears fast, or with a slightly thinner blade that adds play in the keyway. For a key you will carry every day, the material matters.
Near the water, nickel silver holds up better than plated brass, because a plated blank loses its plating at the cut edges immediately and corrodes from there. If a key is going to live in a pocket that goes to the beach, it is worth specifying.
How many spares, and where they should live
The right number of spares is more than one and fewer than you would think.
One key in daily use, one spare held somewhere off the property, and — for a household — one per adult who needs independent access. Beyond that, every extra key is another thing to lose track of, and the whole point of key control is knowing where they all are.
Where the off-property spare lives is the interesting question. A trusted neighbour or a relative nearby is the classic and it is still good, provided you actually would call them at two in the morning. A key kept at a workplace is convenient and only useful during opening hours.
A fake rock, a magnetic box in a wheel arch, above the door frame, under the mat, in the meter box: these are not hiding places, they are the first six places anybody looks. If an outdoor spare is genuinely needed, a mechanical push-button key safe rated for the purpose and mounted into masonry rather than into siding is the honest version — and its code needs changing when the people who knew it move on.
The other honest version is to keep no outdoor spare at all and accept that the occasional lockout is cheaper than the alternative.
Keys wear, and what that looks like
Keys are made of relatively soft metal and they work by being dragged across spring-loaded pins thousands of times. They wear, and they wear predictably.
The first sign is a key that needs to be pulled back a hair or held at an angle. Then it needs a wiggle. Then it works in one lock and not another. The cuts have worn shallower and the shoulder — the stop that sets how far the key enters — has worn back, so every cut is now presenting slightly out of position.
Two habits accelerate it enormously. The first is a heavy key ring: the weight applies leverage every time the key is turned. The second is using one key exclusively while the spare sits in a drawer. That produces the classic situation where the everyday key wears gradually, the lock's pins wear to match it, and then the pristine spare does not work — because the lock has quietly adapted to a key that no longer matches the original specification.
Rotating two keys avoids that. So does replacing a worn everyday key from the code before it takes the lock with it. A worn key does damage in both directions: the lock wears the key, and the key wears the lock.
Do-not-duplicate stamps, and what real copy control looks like
A key stamped “DO NOT DUPLICATE” stops nothing. It is a request printed on metal. The blanks for it are ordinary blanks, sold everywhere, and any self-service machine will cut one without asking.
Genuine copy control is a restricted keyway. The manufacturer holds a patent on the blank profile, the blanks are only supplied to authorised dealers, and keys are only cut for people named on a signed authorisation list held on file. Copying one requires a blank that cannot legitimately be bought.
That is a real product with a real cost and it is not right for most houses. It earns its place where keys circulate among people who change: a small business with staff turnover, a property with contractors coming and going, a building with a board rather than an owner.
For a normal household the practical version of key control is simpler and free: know how many keys exist, know who has each one, and rekey when that list stops being accurate. Which is, in the end, the same discipline at a smaller scale.
What to bring, and what we can do without
- Best case: the key code, or a key that has barely been used. Either produces a key at nominal specification.
- Normal case: your everyday key. We will cut from it, and if it is visibly worn we will say so and offer to decode the lock instead.
- No key at all: the lock can be decoded on site and a key originated from it. This needs proof that the property or vehicle is yours.
- A key that snapped: bring both halves if you have them. A broken key can often still be read well enough to cut from, and the fragment in the lock has to come out either way.
For any key originated rather than copied — a lock decoded, a code used, a vehicle key made — identification and proof of entitlement are required. That is the same standard any locksmith worth calling applies, and it exists to protect the person whose door it is.
Where this brand works
Hurlburt Spare Key is a mobile locksmith covering Hurlburt Field, Wright and Ocean City. Keys are cut at the property or at the vehicle, and the line is answered around the clock.
We quote the whole figure on the phone before dispatch. If a key can be cut from what you already have, we will say so; if the honest answer is that the lock needs decoding or the cylinder is finished, we will say that instead.
Hurlburt Spare Key is a licensed and insured locksmith company operating in Florida.