How A Key Is Actually Copied
A duplicating machine holds two things in line: your original in one vise, a blank in the other. A hardened stylus rides the cuts of the original while a cutter wheel spinning a few inches away removes the same shape from the blank. The two vises are mechanically linked, so whatever the stylus climbs, the wheel cuts. That is the whole principle, and it is why the quality of a copy is decided before the machine is ever switched on.
Three things decide whether the copy works. First, how the original is seated in the vise — a key clamped a hair high or tipped in the jaw transfers that error into every cut along its length. Second, the condition of the cutter wheel; a dull or loaded wheel tears brass instead of slicing it and leaves cuts that measure right and feel wrong. Third, the deburring. A freshly cut key carries a fine curl of brass on the edge of every cut and along the milled groove. Left on, that burr drags on the pins, and the key that felt fine at the counter starts binding a week later once the burr has worn off unevenly and taken some of the lock's finish with it.
A copy made properly gets test-fitted, gets the burr taken off with a wire wheel, and gets checked for the small things a machine cannot see: a blank with a shoulder in the wrong place, a keyway groove that is close but not identical, a tip that is a fraction long so the key bottoms out before the last pin is set.
Why A Copy Of A Worn Key Fails
Every key wears. Brass is soft, pockets carry sand, and the pins in a lock press down on the key's cuts every single time it goes in. Over years the peaks flatten, the valleys shallow out, and the whole profile drifts a few thousandths of an inch from the shape the lock was built to accept. The lock tolerates it, because the lock wore alongside the key and the two settled into each other.
Now copy that key. The stylus faithfully traces the worn shape, so the new key is born already worn — but with none of the give the old one earned. It is a fresh, hard-edged reproduction of a compromised original. Then someone copies the copy, and the drift doubles. This is the single most common reason a customer walks back in holding a key that "was cut wrong." It usually was not cut wrong. It was cut correctly from the wrong thing.
Two symptoms tell you a generation problem is underway. The new key needs to be jiggled or pulled back a hair before it turns, while the old one does not. Or the new key works in the front door but not the back door, even though both locks are keyed alike — because the two locks wore differently and the copy only inherited the tolerance of one of them.
Cutting To Code Versus Copying
There is a second way to make a key, and for a worn original it is the better one. Every pin-tumbler lock has a bitting — a short sequence of numbers describing how deep each cut sits, measured against a standard depth-and-space table for that keyway. Cut to code means a machine indexes off those numbers directly and cuts a key to factory specification. Nothing is traced. The worn original never touches the machine.
The result is a key that matches the lock's design, not the lock's history. It often feels tighter at first than the old key, which surprises people — that tightness is the key being correct rather than accommodating. Within a few dozen cycles the lock settles onto it, and from then on it is the good original that every future copy should be traced from.
Where the code comes from
Sometimes it is stamped on the lock or printed on a card that came in the box and went into a kitchen drawer. Sometimes it can be read from the lock itself by a locksmith with the cylinder in hand. Either way, the useful habit for a household is this: the first time a key is cut to code, keep that key out of daily circulation and label it. It is the master reference. Carry a copy of it, not the thing itself.
Cut-to-code is also the honest answer when someone brings in a key so far gone that copying it would just manufacture a new problem. If the tips are rounded, the shoulder is chewed, or the key visibly bends under thumb pressure, tracing it is not doing the customer a favour.
The Blank Matters More Than People Expect
A blank is not a generic strip of brass. The lengthwise grooves milled into its blade — the keyway profile — have to match the warding inside the cylinder exactly, or the key will not enter far enough to reach the pins. There are hundreds of profiles in ordinary use, and a good many of them look identical at arm's length and differ by a groove depth you would need a magnifier to see.
Then there is the metal. Blanks vary in alloy, in plating, and in how tightly they are held to spec. A thin, soft blank cut to perfect numbers still fails, because the blade flexes under turning torque and the cuts do not stay where the pins need them. Salt air punishes cheap plating too — a poorly plated blank on a beach key ring will pit and shed within a season, and the pitting changes the cut profile.
This is where the cheap copy earns its reputation. A copy cut on a worn machine from a near-miss blank is not a bargain. It is a key that goes into your pocket, works twice, and then leaves someone standing at a door at an inconvenient hour with a key that no longer turns. The trade-off worth understanding is not copy-versus-copy on cost; it is whether the thing you walk out with is a key you can rely on or a key you will be replacing.
Keys That Cannot Be Copied At A Hardware Counter
Two different categories get confused constantly, and the difference matters.
"Do Not Duplicate" stamped on the bow
This is a request, not a lock. A key stamped that way is an ordinary key in an ordinary keyway, and the stamp carries no legal force of its own. Reputable shops honour it as policy and will ask who you are and what your relationship to the property is before cutting. But the stamp does not make the key hard to copy — it only makes people assume it is. Anyone relying on that stamp as a security control is relying on other people's manners.
Restricted and patented keyways
This is the real version. A restricted keyway uses a blade profile that is not sold on the open market; the blanks are controlled and distributed only to authorised dealers, and a patented keyway adds legal protection on top of the physical scarcity. You cannot copy one at a hardware counter because the blank does not exist there to buy, no matter how willing the person behind the counter is.
Getting a copy of a restricted key means going back through the authorised channel and proving you are entitled to it — typically a signature on file, an authorisation card, or documentation tying you to the address or the system. That friction is the entire point of the product. It is what makes a restricted keyway genuinely useful for a rental with staff turnover or a property where key control actually matters, and it is why we will tell you plainly when a key you have brought in cannot be copied here rather than cutting a near-fit that will fail.
If key control is the goal, moving a property onto a restricted keyway is a decision made once, at the cylinder, not something patched later with a stamp.
The Keys People Actually Bring In
Household hardware runs far past the front door, and most of it is quietly single-key.
House and deadbolt keys
The everyday work. Worth doing well because these are the keys that get copied the most times and therefore drift the furthest.
Padlock keys
Storage units, gates, sheds, tool boxes, trailer hitches. Padlocks live outdoors, which means their keys see more grit than any house key ever will. Padlock keys are also frequently the only key, because the second one went with the previous owner of the padlock.
Cabinet, desk and filing cabinet keys
Small flat keys, often wafer rather than pin-tumbler, usually stamped with a code right on the bow or on the lock face. These are almost always better cut to that code than copied, and when the code is present a replacement can be made without the original at all. Offices, workshops and rental laundry cupboards all end up here eventually.
Mailbox keys
Cluster boxes, individual boxes, parcel lockers. Whether a mailbox key can be duplicated depends on who owns and controls the box, and that is worth a conversation before you drive anywhere.
Luggage, bike lock and cable lock keys
Tiny, soft, easily bent, and rarely spared. Bring the lock along if you have it — for small wafer locks the lock itself is often the faster route to a working key.
Shed and gate keys
Outdoor cylinders on a coast take a beating, and a gate key that has stopped working is frequently reporting on the cylinder's condition rather than its own.
Golf Cart, Motorcycle, Marine, RV And Trailer Keys
These are the keys the beach generates in volume, and they are the ones people assume have to come from a dealer.
Golf cart keys are ordinary small-format keys, often shared across whole model runs, and they are lost constantly — they live in pockets that also hold sand and go swimming. Motorcycle and scooter keys are usually a compact double-sided blade, and many older bikes are pure mechanical with no electronics in the key at all. Marine keys — ignition, hatch, console, locker — are their own small ecosystem, and salt exposure means a boat key that "broke" often broke because the cylinder had already seized around it. RV and trailer work spans two worlds at once: the coach door, storage bays and hitch locks are one keying system, and the chassis is another.
The practical point is that a great many of these can be cut from the key you still have, or from the lock itself if you have none, without a trip to any dealer. What varies is whether electronics are involved. A plain mechanical key is a cutting job. A key with a chip in it is a cutting job plus a programming job, and those are two different conversations — worth asking about on the phone before you load anything onto a trailer. Our vehicle key page covers the electronic side.
When There Is No Key At All
A lock with every key lost is not a dead lock. A locksmith can read the cylinder and produce a key that fits it — the trade calls this originating a key, and it is one of the oldest things the job does. The lock does not have to be destroyed and usually does not even have to be replaced.
What we will not do is describe how that is done. That is deliberate. The method is the security, and publishing it would be handing a tool to exactly the wrong reader. What we will describe is the part you need to know as the owner: it requires proof that the lock is yours to open.
What proof looks like
For a house or unit: photo identification plus something tying you to the address — a deed, a lease with your name on it, a utility bill, or a property manager willing to confirm in writing. For a vehicle, cart, boat or trailer: title or registration matching your identification. For a business: identification plus authority to act for the entity, not merely a key to the front door. For a safe or a cabinet: ownership of the thing it sits in, and a straight answer about how it came to be in your possession.
Nobody enjoys being asked. Ask anyway — a shop that will originate a key for a property without checking whose property it is will do the same for someone standing at your door. The paperwork is not bureaucracy, it is the product.
Why A Key Turns Hard, Sticks, Or Suddenly Stops
Half the "my key broke" calls are really "my lock has been failing for months and the key finally paid for it." Sorting key problems from cylinder problems takes about a minute at the counter and saves buying the wrong fix.
Signs the key is the problem
A different key from the same set works smoothly in the same lock. The suspect key has visibly rounded cut peaks, a bent blade, or a bow that has begun to twist. The key works in one lock of a keyed-alike set but not the others. The trouble started right after the key was copied. In these cases you want a key cut to code, not a new lock.
Signs the cylinder is the problem
Every key in the set has become stiff. The key goes in fine but the plug will not rotate without extra force. There is grit or a rasping feel on insertion. The lock is on an exterior door facing weather, and it got worse over a season rather than overnight. The key must be held at a particular angle or pulled out a fraction to work — that is worn pin chambers, not a worn key.
The habit that breaks keys
Turning harder. A key that needs force is telling you something, and force converts a cheap diagnosis into a snapped blade inside a cylinder, which is a considerably more involved job. If a key needs muscle, stop using it and bring it in with the lock's other keys.
Lubrication, and what not to use
Do not put oil or general-purpose spray lubricant in a keyway. Oil is sticky and this is a coast; it will collect sand and grind the pins. A dry lubricant is what belongs in a cylinder. Getting this wrong is a genuinely common cause of a lock that was fine last year and is gritty now.
How Many Spares A Household Should Actually Have
Most households run one key deep and do not notice until the day it matters. A workable arrangement for a single house is four keys with four different jobs.
One is the reference key, cut to code and never carried — labelled, kept flat in a drawer, and used only as the original that future copies are traced from. One or two are the daily carry keys, one per adult, expected to wear out and be replaced from the reference. One is the away key, held by a person you trust who is not in the house — that is the key that resolves a lockout without anyone forcing a door. And for a household with a second driver, a guest room, or a shed that matters, one spare set that stays home.
Where not to keep them: under a mat, over a door frame, in a fake rock, in a magnetic box on a wheel well, or in an unlocked outdoor lock box. Every one of those is a place someone else checks first. If a key genuinely must live outside, it belongs in a rated key safe mounted properly, and it should be a key that opens one door — not the key to everything.
Replace a daily key on wear, not on failure. A carried key that has been in service for years and now feels slightly reluctant is a few weeks from being the reason you call someone at an unhelpful hour.
Sand, Salt And Pocket Grit
Keys on this stretch of coast live a harder life than keys inland. Fine sand is abrasive, works its way into keyways, and rides into the cylinder on the blade. Salt in the air pits plating on the key and the cylinder alike. A key that spends its life in a beach bag or a swimsuit pocket ages faster than the calendar suggests.
Two habits help more than anything sold in a package. Rinse and dry keys that have been in salt water rather than letting them dry with salt on them, and check exterior cylinders once a season for grit before they seize rather than after. Neither takes long, and both push a re-key or a cylinder replacement years further out.
Bringing The Right Thing To The Counter
A short list that makes a key visit a single trip instead of two.
Bring the best original you have, not the most convenient one — if there is an older key in a drawer that has hardly been used, it is worth more to us than the one on your ring. Bring the lock itself when the lock is removable, especially for cabinets, padlocks, lockers and small wafer locks; with the lock in hand a key can often be made straight from it. Bring any code card, tag, or paperwork that came with the hardware. Bring identification for anything tied to a property or a vehicle. And bring the whole set when a key has started sticking, so we can compare a good key against the suspect one in the same cylinder.
If it is easier to describe than to load into a car, call first. Some of it we can settle on the phone.