What a Hardware Store Key Machine Can and Cannot Do

A hardware store key machine is a tracing and cutting device. You hand over a key, the clerk clamps it into one side of a carriage, and a blank of the right shape is clamped into the other. A guide follows the grooves and teeth of the original while a cutter wheel removes metal from the blank in matching places. When the two sides finish their pass, you have a copy of the shape you gave it.

The key word there is shape. The machine copies the outline of the cuts it can see. It does not know what the lock expects, it does not check your key against a code, and it does not care whether the original was cut well. If the original is worn, bent or sloppy, the copy inherits every flaw and may add a few of its own.

For plain brass or nickel plated house keys with a common keyway, that is often good enough. A key is a simple tool at heart, and a simple copy of a simple key frequently works on the first try. The trouble starts when the key is not simple, or when the lock is touchy about small errors.

The strong suit of a store machine is the ordinary mechanical key for a household pin tumbler lock. Front door keys, back door keys, garage side door keys and many padlock keys fall into this group. If the key is in decent shape and the blank is the correct type, a clean copy can come off the machine after a single short pass.

Quality depends heavily on two things: the freshness of the cutter and the care of the person running it. A cutter that is dull leaves burrs and rounded edges. A clerk who rushes may seat the key slightly off true in the clamp, and a small error there turns into a copy that sticks. Both are worth watching for, and both are easy to test before you walk out.

The simple tests are the ones to remember. Ask the clerk to brush off the burrs. Check that the copy slides in and out of the lock without grinding. Turn it with the door open, not closed, and then try it a few times with the door shut. A copy that works only with a wiggle is a copy that will fail when you are in a hurry.

• Common household keys for pin tumbler locks in good condition.
• Many padlock and utility keys with standard keyways.
• Mailbox and cabinet keys, provided the blank matches.
• Spare keys cut from a clean original rather than from a worn copy.
• Keys for locks that tolerate small differences in cut depth.

Some keys are simply outside what the machine can do. A restricted key, which is stamped to forbid copying and cut on a protected keyway, usually cannot be copied at a store, because the blanks are controlled and the store does not have them. Our guide on restricted keys explains why those systems exist and how access to blanks is handled.

Keys with unusual shapes also defeat the machine. Dimple keys, which have round pits drilled into the face of the blade, and laser cut keys, which have a groove milled along the side, need different cutters and carriages. A standard store machine simply cannot trace those cuts, and a clerk who tries anyway will hand you a key that does not work.

Finally, a worn out original can be beyond rescue. When the teeth have been rounded down by years of use, the machine copies the rounded teeth. The result is a key that is a worn copy of a worn key, and each generation gets worse. Our note on what happens when a key wears down goes into this more closely.

People often arrive at the store with a car key and leave disappointed. Most modern vehicles use a key with a transponder chip hidden in the head. The metal blade turns the ignition, but the chip must also be recognized by the vehicle before it will start. A store machine can sometimes cut the blade, and that blade may open the door or turn the ignition by hand, but the engine will not run until the chip is programmed.

Then there are fobs, remote heads and push button start keys. These contain radio circuits and sometimes a hidden emergency blade. A store machine cannot create or program any of that. What you need is cutting equipment that works from the vehicle's key code and a programming tool that can speak to the car, both of which our van carries.

If you are unsure what kind of key you have, our guides on car key types in plain words and transponder keys are good places to start. You can also read our key programming page to see what is involved when the chip is part of the job.

A copy can fail for reasons that have nothing to do with the clerk. Keys and locks are made to tolerances, and a few thousandths of an inch can matter. If the original was cut at the edge of its tolerance and the copy lands on the other side, the pins in the lock will sit just wrong, and the plug will refuse to turn.

Another cause is the blank. A key blank is not just any piece of brass. It has to match the keyway, and many keyways look nearly identical to the eye. A blank that is a close cousin, but not the right one, may slide in and then bind on the warding. Clerks work from charts and catalogs, and mistakes happen when an unusual keyway is mistaken for a common one.

For the longer explanation, our note on why duplicate keys sometimes fail covers the factors in more detail, and the guide to keyways and key blanks shows why the same word on a key can hide several different shapes.

A habit worth building is to test a new key before you leave the counter, and then again at the door it is meant for. Test it first against the original: lay them side by side and hold them to the light. The teeth should line up, the depths should look the same, and the shoulder where the key stops in the lock should sit in the same place.

At home, try the copy in the lock with the door open. Insert it fully, turn it, and feel for roughness or a tight spot. Then try it with the door closed and the bolt extended and retracted. If the key needs wiggling, lifting or pushing to turn, it is not a good copy, and you should take it back rather than hope it improves.

Do not test a new key only once, and do not test it only when you are standing in the dry. A key that works in the warm kitchen may stick on a freezing morning in the mountains of Siskiyou County, when lock grease thickens and a slightly rough cut feels a lot rougher. A few extra tries now will save a frustrating moment later.

There are several situations where going straight to a locksmith will save time. A key for a restricted system, a car key with a chip, a key you have only one of and cannot afford to damage, and a key for a lock that has been giving trouble all belong here. In each case, a copy is only as good as the thinking behind it.

A locksmith can also cut a key by code, without having the original in hand. If you know the lock's key code, or if we can read it from the cylinder, we can cut a key that matches the lock's design rather than the wear on an old key. That is why a locksmith's copy can sometimes work better than the original.

When the real problem is the lock, a better key will not fix it. A cylinder that is dirty, bent or worn will rub even a perfect key. If a new copy sticks and the old one also sticks a bit, look at the lock. Our lock repair page covers what we check and what we do.

There is another limit worth knowing. A key that opens several doors is part of a master key system, and copying it at a store can quietly break the control the system was meant to provide. Offices, apartment complexes and shared buildings use these arrangements so that one key opens many doors while a different key opens only one.

If you are the manager of such a building, think twice about letting anyone copy a master or a sub master key at a counter. Once a duplicate exists outside your control, the entire system depends on trust, and a rekey becomes the only way to take that trust back. Our guide on what a master key system is explains how these systems are laid out.

Even a plain business key deserves care. A shop owner who lets staff copy their own keys will soon lose track of how many exist. Our note on key control for a small business describes habits that keep the count honest without turning the shop into a fortress.

Out in the country, many of the keys people copy are not for the house at all. They open a padlock on a gate, a hasp on a shed, a chain on a trailer or a cabinet in a shop. These are often the easiest keys for a store machine to copy, since many padlocks use common keyways, but they bring their own quirks.

Weather is the main one. A padlock that lives outdoors collects dust in summer and moisture in winter, and its keyway can fill with grit. A fresh copy will not cure a lock that is gummed up, and it may even pick up grit and leave a rough feel. Clean the keyway and put a dry lubricant on it before you decide the key is at fault.

Shared gates deserve a thought as well. If three neighbors share a gate and each has a key, a store copy made by one of them can wander into a fourth set of hands. Our note on farm gate keys and who should hold them looks at keeping that count under control without any fuss.

A bad copy costs more than the few moments it saves. A key that sticks may force you to turn harder than you should, and a hard turn can bend a key or wear a cylinder sooner. A key that snaps in the lock, as can happen with a weak or badly cut copy, leaves you with a broken piece and a door you cannot open.

If that happens, do not push the stub with a screwdriver or a pair of pliers and hope. Our guide on a broken key in the lock explains what to leave alone and what to do, and our lock repair work includes removing a broken piece cleanly.

There is a quieter cost too. A poor copy can make you think a lock is failing when the real problem is the key. People replace locks they did not need to replace because a hurried copy would not turn. A good copy, or a code cut key, can bring a lock you thought was dying back to life.

Between Redding and Mount Shasta, the weather alone puts a lot of stress on keys and locks. Hot dry summers bake dust into cylinders, and cold nights in the mountain towns thicken lubricant. A copy that fits snugly in the warm valley can bind in the cold, so give a key a real test in conditions that match where you use it.

If you can, copy from a key that is clean and fairly new, not from the oldest key on the ring. Keep one original in a safe place and never use it for copying, so that you always have a good starting point. Our note on a spare key now versus later explains the logic of making spares while you still have a working key.

If a store copy does not work and you cannot tell why, send us a note through the request form with a description of the key and the lock. We serve Redding, Anderson, Shasta Lake and the communities up through Siskiyou County, and we will tell you plainly whether you need a better copy, a repair, or a rekey.