What This Guide Covers -- and Who It Helps
Rekeying a cylinder in the field is one of the most common service tasks in commercial door hardware maintenance -- and one of the most misunderstood. Whether you are a school facilities tech responding to a key loss, a commercial sub finishing a punch list, or a building manager handling a tenant turnover, this guide explains what field rekeying actually involves, what tools and consumables you need, when it makes sense versus replacing the cylinder outright, and how cylinder format (standard pin tumbler versus interchangeable core) changes the whole equation.
What Is Cylinder Rekeying?
Rekeying is the process of changing the internal pin stack inside a cylinder so that a new key operates the lock and all previous keys no longer work. The cylinder body, lockset, and hardware stay in place. Only the key pins -- the variable-length bottom pins whose heights correspond to the cuts on the operating key -- are swapped out. When the new key is inserted, each pin stack aligns at the shear line between plug and shell, allowing rotation. Old keys no longer achieve that alignment and cannot turn the cylinder.
Rekeying is not the same as replacing a cylinder, and it is not the same as master keying. It is a targeted change to one level of the key system.
Standard Pin Tumbler Cylinders: The Field Rekeying Process
Mortise cylinders, rim cylinders, and cylindrical lockset plugs are all pin tumbler designs. The field process is the same across formats:
- Remove the plug. For a mortise cylinder, the set screw is backed out and the cylinder is unscrewed from the lock body. The cam stays attached. For a cylindrical lockset, the plug is pushed out from the rear using a follower tool after the retaining clip or cap is removed.
- Use a plug follower. As you withdraw the plug, a plug follower -- a short rod sized to the cylinder diameter -- is inserted immediately behind it to hold the driver pins and springs in the shell. If you let the plug out without a follower, driver pins and springs will fall into the shell chambers and you will spend significant time recovering them. Follower diameter must match the cylinder: common sizes are .500" for many standard cylinders, .498" for universal followers, and .550" for Corbin-type cylinders.
- Remove the key pins. With the plug clear of the shell, insert the existing operating key. Tilt the plug over a pinning tray -- the key pins drop out of each chamber, held in place by the key cuts. Note the chamber positions.
- Install new key pins. Insert the new target key. Drop the correct-depth key pin into each chamber so it sits flush to the shear line with the new key inserted. The new pin depths correspond to the bitting on the replacement key.
- Reassemble and test. Slide the plug back into the shell, compressing the driver pins with the follower as you go. Reinstall the cap or retaining clip, reinstall the cylinder into the hardware, and cycle both the old key (should not turn) and the new key (should turn freely) to confirm.
Key Pins and Pinning Kits
Pin depths are manufacturer-specific and keyway-specific. Mixing pin sets from different manufacturers is not reliable. Quality pinning kits -- available from cylinder specialists such as LAB and others -- include graduated pin assortments and are sold in per-pin quantities or complete refill packs. A curved cylinder shim (approximately .0015" stainless steel) is used by technicians who shim each chamber at the shear line to decode or set pin stacks without a follower in some techniques. Restock shims and pin refills together -- they are high-turnover field consumables.
Interchangeable Core (IC) Cylinders: Rekeying Without Disassembly
IC cylinders change the field rekeying equation entirely. A small-format interchangeable core (SFIC) or large-format IC can be removed from the lockset body using a control key -- no tools, no plug follower, no disassembly of the lockset. The core comes out in seconds. A pre-pinned replacement core goes in. The old core goes back to the shop or a locksmith for repinning or retirement.
This is why IC systems are standard specification in schools, hospitals, and government buildings: a security breach or key loss triggers a core swap at the door in under a minute. The operating key changes, the control key stays the same, and the building is back to full security without a service call to every affected opening.
Brands such as Sargent, Corbin Russwin, and Hager offer IC-capable locksets and cylinders in both 6-pin and 7-pin configurations. SFIC (Best 7-pin compatible format) is the most widely standardized, allowing cores from different hardware manufacturers to share a single key system.
When to Rekey vs. When to Replace the Cylinder
Field rekeying is the right call in most routine situations -- tenant turnover, key loss, staff change. But there are scenarios where replacing the cylinder is the better answer:
- The cylinder shows signs of picking, shimming, or forced-entry damage at the shear line or plug face.
- The keyway is worn or the plug has excessive side play, causing intermittent operation.
- The opening is being upgraded to a restricted keyway or higher-security specification and the existing cylinder body does not support it.
- The cylinder is a non-standard length for the current door or trim and creating a cam alignment problem.
- You are consolidating a key system and the existing cylinders are on an incompatible keyway family.
Cylinder length matters at replacement: the correct length (measured from the cylinder face to the back of the threaded section) must position the cam properly inside the lock body. Too short and the cam will not throw the bolt; too long and the cylinder will sit proud of the trim rose.
Lubrication: The One Maintenance Step Most Cylinders Need Annually
After rekeying or at annual service, lubricate cylinders with a dry-film lubricant -- PTFE-based powder or graphite. Apply directly through the keyway, then cycle the key several times to distribute it through the pin stack. Do not use oil or grease; wet lubricants attract dust, gum up pin chambers over time, and shorten cylinder life. Exterior cylinders and high-traffic openings benefit from lubrication every 60 days.
Field Rekeying Toolset: What Belongs in Your Bag
- Plug followers sized to your cylinder types (.500", .498", .550" as applicable)
- Pinning tray or follower block to catch and organize pins
- Pinning kit with graduated key pins for your keyway family
- Curved cylinder shims (.0015" stainless) for decoding or shimming techniques
- Formed-end tweezers for precise pin placement
- Dry-film PTFE lubricant
- Control key (for IC systems)
- The target new key and the old operating key for testing
Get the Right Cylinders and Rekeying Supplies at DoorwaysPlus
DoorwaysPlus.com stocks mortise cylinders, rim cylinders, IC housings and cores, pinning kits, plug followers, and cylinder accessories from trusted commercial lines including Sargent, Corbin Russwin, Hager, and PDQ. Whether you are rekeying a school after a key loss, securing a tenant turnover in a multi-tenant building, or upgrading a key system across a healthcare facility, our team can help you spec the right cylinder format and core configuration before you order.
Questions about cylinder compatibility, cam selection, or IC core systems? Contact the team at DoorwaysPlus.com -- we work with commercial subs, facility managers, and architects every day on exactly these decisions.