A commercial lock is defined by two things: the lock function (how it latches, what keeps it closed) and the cylinder type (what accepts the key and operates the latch). The cylinder is the part that gets rekeyed, master keyed, or upgraded to a restricted keyway. Understanding the cylinder type matters because it determines what the lock can do, whether it can be master keyed, whether it can be swapped quickly for rekeying, and how it fits into a building’s overall key system.
Mortise Cylinder
A mortise cylinder threads into a mortise lock body, a lock that’s mortised (recessed) into the edge of the door. The mortise lock body contains the latch bolt, the deadbolt (on some models), and the mechanism that connects the cylinder to the latch. The cylinder itself is a threaded brass cylinder that screws into the lock body from the face of the door.
Mortise locks are the standard for heavy commercial doors, steel doors, fire-rated doors, and high-traffic entrances. They’re more secure than cylindrical locks because the lock body is larger, the latch bolt is heavier, and the mounting is more robust. The cylinder can be replaced or rekeyed without removing the lock body, it unscrews from the front.
Mortise cylinders are threaded, which means they have to be the correct length for the door thickness. Too short and the cylinder doesn’t reach the lock body. Too long and it protrudes past the door face, creating a lever point for a wrench attack. The correct length is measured to the door thickness plus the trim ring.
Manufacturers we install: Schlage (L-series mortise locks), Sargent. Both use standard mortise cylinders that can be pinned to a master key system or upgraded to Medeco or Mul-T-Lock restricted keyways.
Rim Cylinder
A rim cylinder mounts to the surface of the door, it sits on the outside face, held in place by a retaining ring and two machine screws that pass through the door to a mounting plate on the inside. The cylinder operates a rim lock or a rim exit device (panic bar) on the inside surface of the door.
Rim cylinders are the standard for exit devices. A Von Duprin 99 series exit device uses a rim cylinder on the outside that retracts the latch when the key is turned. The rim cylinder is also used on surface-mounted rim locks, the kind often found on apartment building entrance doors and rear commercial doors.
Rim cylinders are easy to swap. The retaining ring unscrews, the cylinder pulls out, and the new one drops in. This makes them ideal for buildings that need to rekey frequently, the cylinder can be exchanged in under a minute per door. Rim cylinders are also the standard format for restricted keyway upgrades: a Medeco or Mul-T-Lock rim cylinder replaces the existing cylinder without changing the lock body or exit device.
Key-in-Knob (Cylindrical) Cylinder
A key-in-knob cylinder, also called a cylindrical lock cylinder, is built into a cylindrical lockset (Schlage D-series, Kwikset commercial). The lock body is bored through the door: two holes, one for the cylinder and one for the latch bolt. The cylinder interfaces with the lock body through a tailpiece that turns the latch.
Cylindrical locks are the workhorse of commercial interior doors, office doors, storage rooms, restroom doors. They’re less expensive than mortise locks and faster to install, but they’re also less secure. The latch bolt is smaller, the lock body is lighter, and the cylinder is integrated into the knob or lever rather than being a separate component.
The cylinder in a cylindrical lock can be replaced, it’s called a “removeable core” in some models, but it’s more involved than swapping a rim cylinder. On a Schlage D-series, the cylinder is accessed by removing the inside rose (the trim plate behind the inside knob), which requires removing the knob first. On interchangeable core versions, the core pulls out with a special control key.
Interchangeable Core (IC)
An interchangeable core is a cylinder design that allows the entire pin tumbler assembly to be removed and replaced without disassembling the lock. The core is held in place by a retaining clip. A special “control key” is inserted, the retaining clip releases, and the core slides out. A new core slides in, the control key is removed, and the lock is rekeyed.
The advantage is speed. A building with 50 doors on an IC system can be rekeyed by one person in under an hour, pull the old cores, insert the new cores, done. No tools beyond the control key. No removing lock bodies, no unscrewing cylinders, no taking apart the door.
IC systems come in two formats:
Small formatthe original design, used on Schlage and other cylindrical locks. The core is smaller and fits inside a standard cylindrical lockset.
Large formata bigger core used on mortise locks and rim cylinders. The large format core is more robust and is the standard for commercial IC systems on heavy doors.
IC systems are specified by keyway: SFIC (Small Format Interchangeable Core) is a generic standard that’s compatible across multiple lock manufacturers. LFIC (Large Format Interchangeable Core) is typically manufacturer-specific.
Which Cylinder Type for Which Application
- Heavy commercial doors, fire-rated doors, main entrances: Mortise lock with a mortise cylinder. Most secure, most durable, most serviceable.
- Exit devices (panic bars): Rim cylinder on the outside. Standard for all rim exit devices.
- Interior office doors, storage rooms: Cylindrical lock (key-in-knob/lever). Adequate security, lower cost.
- Buildings that rekey frequently or have high turnover: Interchangeable core (IC). Fastest rekeying, lowest labor cost per rekey.
Restricted Keyway Upgrades
Every cylinder type discussed above, mortise, rim, cylindrical, and IC, is available in Medeco and Mul-T-Lock restricted keyway versions. The upgrade replaces the cylinder or core while keeping the existing lock body, exit device, or lockset. The door prep doesn’t change. The hardware stays the same. Only the keyway changes.
This is how a building upgrades from standard keys to restricted keys without replacing every lock on every door. The Medeco or Mul-T-Lock cylinder drops into the existing hardware, the new keys are cut to the system’s pinning chart, and the building’s key control is immediately upgraded.
Pro Locksmith LLC is an authorized dealer for both Medeco and Mul-T-Lock. We upgrade existing commercial lock systems to restricted keyways throughout Broward County and Miami-Dade. Licensed and insured. Flat-rate pricing quoted up front. Employees, not subcontractors.
For a cylinder evaluation or restricted keyway upgrade, call Pro Locksmith LLC at (954) 406-8266.
Sources
- ANSI/BHMA A156.2, Bored and Preassembled Locks & Latches (cylindrical locks)
- ANSI/BHMA A156.13, Mortise Locks
- Medeco Security Locks Product Catalog
- Mul-T-Lock 2016 Product Catalog
Storefront Doors and the Narrow Stile Mortise Cylinder
Most retail storefronts in South Florida use aluminum and glass doors with a narrow stile, the thin vertical frame along the edge of the glass. These doors do not have room for a standard mortise lock body. Instead they use a narrow stile deadlock, often the Adams Rite style that has become the common pattern for this kind of door, with a hook bolt that swings out into the frame.
These deadlocks still take a threaded mortise cylinder, but the cylinder has to be matched to the lock with the correct cam, the flat piece on the back of the cylinder that turns the lock mechanism. A standard cam from a heavy mortise lock will not operate a narrow stile deadlock correctly, and the wrong cam is one of the most common reasons a replaced storefront cylinder turns but does not throw the bolt. When we replace or rekey a storefront cylinder, we match the cam to the lock rather than assuming the one on the old cylinder was correct.
Storefront doors usually have a cylinder on the outside and either a thumbturn or a second cylinder on the inside. A double cylinder setup means someone inside needs a key to get out, which has real implications for code and life safety on doors that serve as exits. If you are changing that configuration, check with your building manager or the local building department before you commit to it.
Cam Cylinders for Cabinets, Drawers and Display Cases
Commercial buildings are full of small locks that are not on doors at all: file cabinets, desk drawers, cash drawers, mailboxes, jewelry display cases, electrical panels and locker banks. Most of these use a cam lock, a short cylinder with a flat cam on the back that rotates to block the drawer or door from opening.
Cam locks come in many lengths and cam shapes, and the cam can be set to rotate 90 or 180 degrees depending on the application. When a business wants these locks to fit into its key system, many cam locks can be pinned to the same key as the doors or keyed to a master key. That means a manager can open every display case or cabinet with one key while employees have access only to the ones they need.
Display case locks in retail stores deserve particular attention. They are often plunger locks or sliding door locks, and the cheapest ones come keyed alike from the factory, which means the same key opens every case of that model everywhere. For a store with valuable merchandise, rekeying those locks to a unique key, or replacing them with locks that can be rekeyed, is one of the simplest security improvements available.
Tubular and Key Switch Cylinders
A tubular cylinder uses a round key with cuts around the end instead of along the blade. You see them on vending machines, alarm arming switches, some bike locks, coin boxes and certain cabinet locks. They are harder to handle for someone without the right tools, but they are not especially high security, and the round keys are widely available in common key codes.
Key switches are cylinders connected to an electrical switch rather than a latch. They control things like alarm systems, elevator recall, automatic door operators, gate operators and overhead door controls. In a commercial building, key switches are often overlooked when a key system is planned, and they end up on random factory keys that nobody tracks. Bringing key switches into the building’s key system, or at least documenting who holds those keys, closes a real gap in key control.
Cylinder Hardware That Makes or Breaks the Install
A cylinder is only as good as the parts that go with it. On mortise and rim cylinders, several small components decide whether the lock works correctly and how well it resists attack.
Cams and tailpieces
Mortise cylinders use cams that must match the specific lock body. Rim cylinders use a tailpiece, the flat bar that extends through the door to operate the exit device or rim lock. The tailpiece has to be the right length for the door thickness and oriented correctly for the device. A tailpiece that is too short will not engage, and one that is too long can bind.
Blocking rings and spacers
When a door is thicker than standard, or a mortise cylinder is slightly too long, a blocking ring, sometimes called a spacer or collar, fills the gap so the cylinder sits flush and tight. Leaving a gap under the cylinder face invites the same wrench attack that an overly long cylinder allows.
Security collars and cylinder guards
A spinning security collar surrounds the cylinder face and turns loosely when gripped, so it cannot be used to twist the cylinder with pliers or a pipe wrench. Hardened steel versions also resist being cut or crushed. On a mortise cylinder the collar takes the place of a standard trim ring, so it has to be accounted for when choosing the cylinder length. Rim cylinders on exposed rear doors, warehouse entries and service doors benefit from a cylinder guard plate bolted through the door. These parts cost little compared with the damage from a successful forced entry and are worth considering on any exterior commercial door.
How to Identify What You Have
If you are a facility manager trying to take stock of your building’s locks before calling a locksmith, a quick visual survey helps.
- A round cylinder face flush with a rectangular lock case or escutcheon on the door edge, with a lever or knob on its own trim, is usually a mortise lock.
- A round cylinder on the outside face of the door with a push bar on the inside is almost always a rim cylinder on an exit device.
- A keyhole in the center of the knob or lever itself is a cylindrical lock.
- A cylinder with a small figure-eight shaped face, with a second smaller lobe near the keyway, is typically an interchangeable core.
- A cylinder on a narrow aluminum door frame next to glass is a narrow stile mortise cylinder.
Also look at the keys themselves. The brand name stamped on the key bow and any number stamped on it tell a locksmith a lot about the existing system. Photos of the lock faces and the keys, taken straight on, make an evaluation faster.
Keyways and Why They Matter to Your System
Every cylinder has a keyway, the shaped slot that determines which key blanks will fit. Common commercial keyways from major manufacturers are widely available, which is convenient for duplication but means anyone can buy those blanks. The number of pins in the cylinder also matters. A five-pin cylinder offers fewer possible key combinations than a six-pin cylinder, which limits how large and flexible a master key system can be.
When a building has a mix of brands and keyways, it often cannot be brought under a single master key without changing some cylinders. That is not always a problem, but it is worth knowing before planning a key system. A cylinder survey shows exactly which doors can be pinned into the new system as they are and which need a new cylinder or core.
Salt Air, Heat and Cylinder Life in South Florida
Cylinders on exterior doors near the coast, in Fort Lauderdale, Pompano Beach, Hollywood, Hallandale and along the beach communities, face salt-laden air that corrodes metal parts faster than inland. Rain driven by summer storms pushes water into keyways, and afternoon heat on dark doors can be significant. Signs that a cylinder is suffering include keys that need wiggling, green or white residue around the keyway, and a cylinder face that looks pitted.
A few habits extend cylinder life. Use a dry lubricant made for locks rather than oil, which traps sand and grit. Keep door weatherstripping and drip caps in good shape so water is not channeled onto the lock. On doors facing the ocean, plan on inspecting cylinders more often than on interior doors. And when a cylinder starts to bind, service it before a key breaks off inside it on a busy morning.
Keeping a Cylinder Record for Your Building
One of the most useful things a commercial property can have is a simple list of every door, its lock type, its cylinder type and which key operates it. That record makes rekeying faster, keeps a master key system organized as tenants change, and gives a new property manager a clear picture on day one. At minimum, the record should include:
- A door number or location for each lock
- The lock type and cylinder type, including any interchangeable core format
- The keyway and whether the cylinder is part of a master key system
- Who holds keys to that door and how many copies exist
- The date the cylinder was last rekeyed or replaced
We can help build this record during a cylinder evaluation, and keep it current as changes are made.
Commercial Service Area
We evaluate, rekey and replace commercial lock cylinders for warehouses, retail storefronts, office buildings, restaurants and multi-tenant properties throughout Broward County and into Miami-Dade, reaching Aventura, North Miami, Miami, Coral Gables and Coconut Grove. For commercial clients we also travel north through Boca Raton, Delray Beach and Boynton Beach up to West Palm Beach. Whether you need a single storefront cylinder matched to the right cam or a full survey of a building with dozens of doors, we start by identifying exactly what is installed so the recommendation fits the hardware you have.