Glossary of Locksmith Terms
If I had a dime for every time someone called a panic bar a crash bar, I would buy myself a hamburger with all those dimes. This column is meant to sort out such terminology and should be consulted if one encounters an unfamiliar term in later columns. This is not an encyclopedia of the locksmith trade. Terms will be added later if I write a column that mentions some item and I feel that it needs to be defined.
ALOA. Associated Locksmiths of America. A training organization that grants locksmiths certification in particular skills. When shady locksmiths say they are “licensed” and “certified,” they are usually referring to their ALOA membership and completion of some training class, respectively. In fact, locksmith licenses are granted only by state governments and certification addresses only skills, not honesty. I filed a complaint against ALOA for plagiarizing my website. Mary May, their executive director, told me that she does not believe it is wrong to copy and paste other people’s website content, but the plagiarized material was eventually removed.
ANSI: American National Standards Institute. The extant grading system, which focuses on the strength of locks against physical attacks by primitive tools like sledge hammers, crow bars and reciprocating saws. They do a cycle test, a resistance test, a door impact test, a warped door test and a bolt strength test. They do not specifically mention picking or bumping open locks; both Grade 1 and 2 are supplied with the same fairly well-machined six-pin cylinder. These cylinders are certainly better than ungraded cylinders, but are neither pick-proof nor bump-proof. It is usually easy to swap them for cylinders of other brands, including high-security cylinders. Grade 3 (residential-grade) locks typically have proprietary cylinders and thus cannot be upgraded to better ones.
ASSA. A Swedish lock manufacturer; not to be confused with Abba, the 1980’s Swedish band. ASSA has a full line of lock products in Europe but, in this blog, when I say ASSA I am specifically referring to their V-10 cylinders, which are the only product they currently sell in America.
Barrel Bolt. A steel bolt in a cylinder that attaches to the inside of a steel door so the bolt can slide into a hole in the door frame. It is inexpensive compared to deadbolts and quite secure, largely because it is not visible on the outside and so does not give the burglar an aiming point for his sledge hammer. It does not require a padlock but can accept one, which prevents employee theft. It cannot be used on fire exits.
Blaze, Matt. A cryptographer who published a paper, Rights Amplification in Master-Keyed Mechanical Locks, that describes (but offers no solution to) an attack on masterkey systems. This attack allows an employee who has been issued a key to his own office to obtain a master key. My Anti-Blaze Masterkey System stymies thieves attempting a Blaze attack.
Bolt. The part of a deadbolt that extends 1” into the strike plate. It is dead in the sense that, once thrown, it cannot be pried out of the strike plate, but must be retracted by the locking mechanism. A deadbolt does not lock automatically when the door is closed but must be manually locked.
Bond. Insurance against theft or unauthorized distribution of a customer’s keys. Contrast this with licensed, insured and certified, which are also defined in this glossary.
Bow. The part of a key that one grips with one’s fingers.
Bump. A technique for opening a pin tumbler lock that involves moving the pins up and down. It leaves no mark and makes a noise similar to driving a nail. It does not rotate the pins and so cannot open Medeco locks. It can (theoretically) open ASSA or Primus locks, provided that the correct blank is used, though retracting the sidebar and opening a gap between the bottom and top pins is not necessarily simultaneous. Smart Key is not pin tumbler, so it cannot be bumped.
Bump Stop. A trademarked name of a cylinder manufactured by Master. It is difficult to bump but easy to pick. It cannot – like all pin-tumbler locks – be twisted open like the Smart Key. It is no more difficult to drill than any pin-tumbler lock.
Certification. A document stating that one has completed a training course and passed a skills test. Manufacturers of complicated products, like time delay safes, deny factory support to technicians who are not certified. ALOA also certifies locksmiths in more general skills. Contrast this with bonded, insured and licensed, which are also defined in this glossary.
Classroom Function. A knob or lever in which the inside is always unlocked and the outside can be toggled from the locked to the unlocked position with the key. This function was invented because entrance function levers allow the students to lock their teacher out if she leaves the room without her key.
Clutch. A lever that turns even when it is locked. Grade 1 levers must have a clutch. Un-clutched levers are rigid when locked and, while they will not open, they will be bent if burglars pry on them. But clutched levers can be confusing to the user who thinks they are malfunctioning when the lever turns and the lock does not open.
Commercial. A building used by one’s employees or by customers. The locks must meet higher standards than those on a residence that is used only by one’s family and invited guests.
Commercial Grade. In the ANSI system: 1) A heavy duty knob, lever or deadbolt with much durability and strength against physical attack, like hammering on a deadbolt with a sledge hammer or prying on a lever with a crow bar. 2) A medium duty knob, lever or deadbolt that meets the minimal requirements for strength and durability for use on commercial buildings. Note that both grades are currently supplied with the same cylinders, though either will accept after-market high-security cylinders. In the four-tiered grading system that I propose, this stock cylinder is either Grade 3 or 4, depending on the manufacturer.
Control Key. A key that inserts or removes the core of an interchangeable or removable core lock. When one turns the control key, instead of operating the lock, the key only rotates about 20° and then the lug retracts so the core can be inserted or removed.
Conventional. A pin tumbler cylinder that is neither interchangeable nor removable; that is, the lock must be disassembled to rekey or replace the cylinder. Conventional cylinders with standard external dimensions will fit in any ANSI Grade 1 or 2 knob, lever or deadbolt (with the appropriate tailpiece), though there are also ANSI Grade 3 cylinders that are conventional but only fit in the lock they came with.
Core. A cylinder that can be inserted and removed with a control key, without having to disassemble the lock. This allows the owner to swap cores without having a locksmith go to the location to rekey the lock. The owner still needs to periodically bring his spare cores to a locksmith to be rekeyed. There are two types: interchangeable and removable.
Cylinder. The part of a lock that determines which key will operate it. The term cylinder includes not just the cylindrical portion, but also the plug that rotates inside it. A core is a type of cylinder but, for clarity, I will not use the term cylinder when discussing interchangeable or removable cores.
Deadbolt. A lock that uses a bolt, not a latch.
Dog. To set a panic bar in the unlatched position so the door can be pulled open from the outside. One must depress the panic bar with one hand and then dog it into place by turning the dogging key with the other hand.
Dogging Key. An Allen wrench with a large bow for use in dogging a panic bar. Some panic bars (e.g. Corbin Russwin) require an actual key to dog the bar.
Drill Resistant. Any pin tumbler lock with a sidebar is drill resistant because there are two drill points. Even without the sidebar, the addition of steel inserts to deflect a drill qualifies as drill resistant. Medeco and ASSA have sidebars and both drill points (shear line and sidebar) are protected by steel inserts. Best and Primus both offer steel inserts as an option, though the latter is already drill-resistant because it has a sidebar.
Entrance Function. A knob or lever with a mechanical switch on the inside that allows the lock to function as either a passage function or a storeroom function lock. It can also be set to operate in the storeroom function until the first time the key is used, when it reverts to passage function.
Fire Exit. A door with a lighted sign labeling it as an exit; it has a panic bar and no deadbolt or barrel bolt. If it has the lighted sign then it must have the appropriate hardware, even if one is not required to have a fire exit there.
Flip Latch. A little hinge that screws into the door frame and can be flipped over the door from the inside. Flip latches are no good. They sometimes flip into the locked position if one slams the door. When this happens, the door can be opened with a shove, usually causing very minimal scratches on the door. If you have one, remove it and throw it in the trash.
Glass-and-Aluminum Door. A door with a narrow aluminum frame around a large window. Also called a storefront door because almost all stores in America (but not Europe) use this type of door for their entrance.
Guru. No offense to Hindu people, I use the term to describe those who make a show of their skill at opening locks, usually by posting YouTube videos on the internet. I also use this term to describe an HPC Masterking Monkey.
Handing. If, when viewed from the outside, the hinges are on the left, then it is a left-hand door. If the hinges are on the right, then it is a right-hand door. This matters if a lever is not straight, because the convex side is supposed to go upward. Many modern levers allow the inside and outside to be interchanged, but past levers typically had to be purchased left- or right-handed.
Hardened Ring. A device to prevent the wrenching of mortise cylinders. Also known as a spinner.
High Security. A cylinder that uses a different technology than standard-security cylinders and is pick-proof, bump-proof and drill-resistant. Generally, this is any standard-security cylinder with the addition of a sidebar. ASSA, Medeco and Primus are examples. Having the tip of the key engage a little pin, like on Everest cylinders, is not a sidebar and is not high security. Smart Key has a sidebar but is not high security because of its fragility. KeyMark is not high security; putting a patent on a funny-shaped keyway is insufficient by half. There are also some very unique designs. Abloy (Finnish) has stood the test of time, while others are too obscure for me to judge, though neither should they be rejected out of hand. Mul-T-Lock (Israeli) has gained a footing in America, though I personally do not have enough familiarity with them to comment.
Hook. A long bottom pin with a short bottom pin immediately behind it. On a masterkeyed cylinder or core, the hook is defined as the difference between the deeper of the two shear lines in a pin chamber and the one immediately behind it. The larger the hook, the more difficult the cylinder or core is to pick.
HPC Masterking Monkey. A locksmith who considers himself an expert at masterkeying locks when, in fact, his expertise does not extend beyond knowing how to download and run the very simplistic Masterking software sold by HPC.
Institutional Function. A knob or lever with classroom function on both sides; there is no inside and outside because both sides have key cylinders. They are called institutional because they are used in the hallways of insane asylums where there are crazy (but not particularly resolute) people on both sides of the door.
Insurance. Insurance against inadvertently damaging something. For instance, when installing a lock in a door with a window pane, the locksmith might hit the glass with his drill and break it. Contrast this with licensed, bonded and certified, which are also defined in this glossary.
Interchangeable Core. See SFIC and LFIC.
Key Control. Effort made by manufacturers to prevent criminals from obtaining keys that enter their keyways. There are two different types of keys that will enter a keyway: blank keys with no cuts on them and used keys with random cuts on them. Preventing criminals from obtaining blank and used keys are different problems, though current use of the term “key control” conflates them.
Keyway. The opening in a plug that admits the key; its shape determines which type of key is used. Kwikset, KW1, is widely used on residential locks; Schlage, SC1 or C, is also used on residential-grade locks, though Kwikset-compatible locks are more common than Schlage-compatible locks. The Schlage SC4, a six-pin version of SC1, is the most common keyway on commercial-grade locks in America. A Primus key will pass an SC4 keyway, but not vice-versa. Sargent and Yale are better quality commercial locks and their most common keyways are LA and Y2, respectively. Schlage, Sargent and Yale all have other keyways, some quite obscure, which reduces the chance of unauthorized duplication. High-security cylinders such as ASSA or Medeco have proprietary and patented keyways.
Knob. A lock that uses a latch, not a bolt.
Latch. The part of a knob or lever that extends ½” into the strike plate. It is spring loaded so it can lock automatically when the door is closed.
Latch Protector. A steel plate that attaches to a door and protects the latch from being cut with a reciprocating saw. It also has a pin that inserts into a hole in the frame to help prevent the door from being pried away from the frame. Similar plates used over deadbolts and mortise locks are also called latch protectors, though they are actually protecting a bolt. This is only used on commercial doors, which always open outwards; residential doors open inwards and cannot have latch protectors, though the wooden door stop provides some protection.
Lever. The same thing as a knob, except with a lever to allow people to get a better grip. They are more durable and also more expensive; sometimes required for handicapped people.
LFIC. Large Format Interchangeable Core. Similar to SFIC, except with a standard size of plug and pins and using the same keyway as conventional locks; conventional and LFIC locks can be intermingled. LFIC has a small lug engaged by only some of the cuts on the control key, so the other cuts are the same as an operating key, usually the master key. I exclude removable core locks from the LFIC definition, though the manufacturers of removable core locks call themselves LFIC.
License. It is the state government – not any other entity – that licenses locksmiths. Not all states do this (Arizona does not) but, when they do, it is illegal to operate or advertise a locksmith business without a license. See Locksmith Scammer for loopholes in this law. Note that a locksmith’s license is not the same thing as a contractor’s license; contractors install locks as they are provided from the factory, which operate with an uncut key blank. The contactor is not allowed to handle the end user’s key, while locksmiths are not allowed to make structural changes to the building. (If your key does not have any cuts in it, then you need to call a locksmith; that is the contractor’s key.) Contrast licensed with bonded, insured and certified, which are also defined in this glossary.
Lock. A device that holds a door shut. The term lock includes the latch or the bolt and also the cylinder. In residential-grade locks the cylinder is an integral part of the lock, but in commercial locks the cylinder is sold separately, which allows the use of cylinders with other keyways, including high-security cylinders.
Locksmith Scammer. A criminal organization that spoofs legitimate locksmiths by listing their own telephone number in the 411 directory under the name of the legitimate locksmith. It does not replace the real locksmith’s number but is listed alongside it, so the 411 operator will say, “we have a half dozen companies by that name, which one do you want?” The numbers have a local area code, but forward to a call center. If you are unsure of who you are speaking to, ask them the name of their company; if they respond with “I’m the locksmith you called,” then they are a locksmith scammer. Also, scammers use paid Google Adwords campaigns to promote sites with names like “Local Locksmith” or “Locksmith Near You” that are actually call centers with 8** area codes. It should go without saying that you should never dial an 8** area code.
Lug. A bar or pin that extends out the side of an interchangeable or removable core and holds it in place until a control key is inserted and turned. On SFIC cores, it is engaged by all of the pins; on LFIC cores, it is engaged by some of the pins; and on removable cores, it is engaged by an extra long tip on the control key.
Mag Plate. A trademarked name of an after-market plate made by MagLock to protect a wooden door from splitting near the deadbolt. Also, after a door has been kicked open, the same plate can be used to squeeze the split halves together to repair it if the homeowner cannot afford a new door. MagLock also makes large strike plates with long screws.
Maximum Security. A trademarked name of a discontinued deadbolt made by Schlage. It was difficult to pick because it came with spool pins from the factory, though this did not affect bumping it open. It had a five-pin proprietary cylinder that, unlike all other Schlage deadbolts, could not be upgraded to a six-pin SC4 cylinder or replaced with another brand of cylinder. Its bolt had the unpleasant habit of occasionally falling to pieces, which is probably why the lock was discontinued.
Medeco. An American lock manufacturer; they are now owned by ASSA, but operated independently and with their own patented designs. In this blog when I say Medeco I mean their Biaxial design. The only exception is my column about key control, where I will discuss their standard-security KeyMark design, which is not mentioned elsewhere.
Mortise Cylinder. The type of lock cylinder used on mortise locks. It is not interchangeable with those cylinders used on knobs, levers and deadbolts. For some reason, ANSI does not grade mortise cylinders – only knob, lever and deadbolt cylinders – and so the mortise cylinders supplied by contractors are often junk; five pin chambers and very loose machining. Locksmiths can replace junk mortise cylinders with better ones, though lazy locksmiths will just dump the sixth pin chamber from all the good quality cylinders to make them compatible with the junk five-pin mortise cylinder on the front door.
Mortise Lock. A lock that is installed through the edge of the door. Separate inside and outside cylinders screw in from either side. All glass-and-aluminum doors have mortise locks. Before WWII, almost all locks were mortise locks, but deadbolts are now much more common on wood and steel doors. Mortise locks are weak on wood doors because so much wood is removed, but they are viable on steel doors. Once the hole in the door has been cut, the deadbolt/mortise decision cannot be undone.
Padlock. A lock with a shackle that can secure a barrel bolt or a chain. Abus makes padlocks that can use the same key as the building and can be rekeyed to be part of the masterkey system. The most insecure thing about padlocks is that, if they are left hanging loose, they can be stolen and then decoded. Abus padlocks have the option of being key retaining, which means that the key cannot be removed unless the padlock is locked. This prevents the padlock from being stolen and decoded, but it is also confusing for people who think their lock is malfunctioning when they cannot get the key out.
Panic Bar. A lock that can be opened by pushing on it with one’s body, without the use of one’s hands. Note that “crash bar” is NOT the correct term for these locks; a crash bar protects the wall from carts and forklifts, which has nothing to do with locksmithing. This confusion probably results from the fact that factory workers sometimes install a panic bar for the purpose of hitting it with their cart rather than stopping to turn a lever and then pulling their cart through. This practice is hard on panic bars and potentially dangerous for pedestrians on the other side of the door. Of course, levers do not last long under these conditions either because they catch at passing carts; a plastic bumper can be installed to protect a lever.
Passage Function. A knob or lever that can be opened without a key. Its only purpose is to hold the door shut against the wind, or to isolate a noisy area of a factory.
Patio Door. A large pane of glass in a very thin aluminum frame that slide in tracks past another similar pane of glass in a fixed frame. These doors are intended for upstairs balconies but will function as a back door to your patio or pool IF your back yard has a high and sturdy fence. They are neither secure nor reliable when used as an entrance.
Pick. A technique for opening a pin tumbler lock that involves moving the pins up and down. It leaves no mark and is silent. It does not rotate the pins and so cannot open Medeco locks. It does not retract a side bar and so cannot open ASSA or Primus locks. Neither does it work on Smart Key locks, which are not pin tumbler. It is frustrated by spool pins.
Plug. The part of a lock cylinder that will turn if the correct key is inserted.
Privacy Function. The same thing as an entrance function lock except, instead of requiring a key, it can be opened with a screw driver or some similarly primitive tool. It is used on bathrooms to preserve modesty when the bathroom is in use, but to still allow the door to be opened in the event of an emergency.
Profile Cylinder. Profile cylinders are similar to mortise cylinders except that the inside and outside cylinders are attached to each other and slide all the way in from one side; they are then held in place by a bolt threaded in from the edge of the door. They are used in America on upscale residential security doors, but are used in Europe where we usually use mortise locks.
Public Building. A building that can contain large numbers of people. Panic bars are required on fire exits with lighted signs. Consult your fire code for a rather headache-inducing definition of what constitutes a large number of people and how many fire exits they need.
Removable Core. Similar to a LFIC core except that control key does not differ in any of its cuts from the operating key. The control key is an operating key, usually the master key, duplicated onto a special blank with an extra long tip to engage the lug. I do not consider removable core locks to be LFIC, though the manufacturers of removable core locks call themselves LFIC.
Residential. Kwikset and compatible knobs and levers are called entrance function but are really not because, when the mechanical switch is set to make it storeroom function, the inside is locked; true storeroom function would require the inside to be open without having to stop and turn the little switch. This makes them more dangerous in a fire because people may not find the little switch, and so a residential knob or lever is disallowed on commercial buildings. However, residential knobs and levers give positive confirmation that the door is locked without having to remember which way the little switch must be positioned to lock the door; this makes them more secure against inadvertently leaving them unlocked.
Residential Grade. Schlage and compatible knobs and levers are true entrance function locks and are thus not “residential” as defined in this glossary. However, the cheap ones that are neither Grade 1 nor 2 and thus disallowed from commercial buildings are called residential grade or Grade 3; this does not have to do with their function but only their lack of strength. Grade 3 locks have a variety of cylinders, usually proprietary, so they cannot be upgraded with better after-market cylinders. Locksmiths often use the terms “residential” and “residential grade” interchangeably to indicate any lock not allowed on commercial buildings. In this glossary I clarify: Residential is a knob or lever that is disallowed from commercial buildings because it does not meet the fire code requirement of allowing egress without having to flip any little switches. Residential grade is a knob, lever or deadbolt that is disallowed from commercial buildings because it does not meet the requirements for Grade 2 strength.
Rose. The round part of a lever that presses against the door. Residential-grade levers have small roses; commercial-grade levers have large roses that are anchored to the door with through bolts above and below the 2⅛” hole. These bolts strengthen the lever if a burglar pries on it with a crowbar. Beware of lazy locksmiths who do not bother to drill the holes for the through bolts; this is really fraud because they accepted payment for a commercial-grade lever but, without the through bolts, it is no stronger than a residential-grade lever.
SFIC: Small Format Interchangeable Core. A core with a large lug engaged by all of the pins, so the control key may differ entirely from any operating key. The plug and pins are smaller than other locks. The system was designed by Best, though their patent expired a long time ago and cores are now available from several companies, so it is not accurate to describe all SFIC cores and hardware as Best.
Sidebar. A secondary locking mechanism used on high-security pin tumbler locks. In addition to the pins themselves blocking the movement of the plug in the cylinder, there is a bar on the side of the plug.
Smart Key. A trademarked name of a cylinder manufactured by Kwikset. It is fragile and can be twisted open; the ones in knobs can be pulled out. It cannot be picked or bumped and it is drill resistant, but I do not consider it high security because of its fragility. It does not fit in Grade 1 or 2 locks but only in the residential-grade Kwikset locks that were designed for it.
Snap. A technique for opening profile cylinders. Yale, an English manufacturer, advertises a profile cylinder that resists being snapped. This is of little concern to Americans.
Spinner. See hardened ring.
Spool Pins. Top pins shaped like miniature spools of sewing thread. They make a lock cylinder more difficult to pick open. They do not affect bumping or drilling the lock.
Standard Security. A cylinder that uses the basic pin tumbler mechanism patented by Linus Yale in the 1860s. There is no sidebar. But standard security cylinders should not be rejected out of hand; some contain steel inserts to resist drilling, some contain spool pins to resist picking and some are machined to such close tolerances that they rival high security cylinders.
Steel Door. A door 36” wide and 80” high made of steel with no window. (In rare cases they have a tiny window so workers can check for prowlers before opening their back door.) It is usually set into a masonry or solid concrete wall. It is also called a man door to distinguish it from roll-up garage doors or very large hinged doors that can admit a forklift. The knob, lever or panic bar is 36” above the floor. The deadbolt or barrel bolt is above that.
Storeroom Function. A knob or lever that is always locked and requires a key to open from the outside. It is always open from the inside, as required on commercial buildings, so people inside do not have to fumble with any little switches in the event of fire.
Strike Plate. A plate attached to the door frame with a hole in it that the bolt or latch extends into. Some inexpensive residential locks have small strike plates and short screws; they can be made more secure by purchasing a large strike plate with long screws. This is less expensive than replacing the whole lock. Better quality deadbolts come with secure strike plates but they are usually in two pieces, an inner one that provides the security and an outer decorative plate that matches the color of the deadbolt. Beware of lazy locksmiths who just install the decorative plate to avoid chiseling out a deep hole and drilling long holes into the 2×4.
Trapeze Bar. An old-fashioned style of panic bar. They were discontinued because, as the springs weaken, the weight of the bar partially or wholly retracts the latch. Also, the springs on either end did not wear out at the same rate, which left them crooked and unreliable. They were not sturdy and would bend or fall apart if hit with a cart.
Twist. (1) A technique for forcibly turning the plug of Smart Key cylinders; it does not work on pin tumbler locks. It is silent. (2) A dance performed by burglars who have just opened your Smart Key lock in ten seconds, just like the video they found on the internet demonstrates.
Ward. A ward is the inverse of a groove; similar to a land in the rifled bore of a gun. In the keyway of a lock cylinder, the ward is the protrusion that the pins rest on when there is no key inserted into the lock. If the ward is high, as it is in Kwikset-compatible and Schlage-compatible locks, then there is no room for a large difference between the shortest and longest possible bottom pin. Sargent and Yale cylinders are more secure, not just because they are machined to closer tolerances, but because their ward is lower and thus allows a larger difference between the shortest and longest possible bottom pin.
Wrench. A technique for forcibly removing mortise cylinders. It is silent.
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