How to Change Your Lock Cylinder
If all you need to do is change the key to your lock, and you are fairly good with tools, you may want to do it yourself. Or, you may want to remove the lock and bring it to a locksmith to be rekeyed. In rekeying, only tiny parts within the cylinder are changed; the rest of the lock stays the same.
Following is an overview of the various locks there are and how to change them.
In order to change your lock, you can replace your entire lock, or you can replace just the cylinder, or you can take just the cylinder to a locksmith to be rekeyed. There are three basic types of cylinders:
- Rim cylinders
- Mortise cylinders
- Cylindrical lock or tubular deadbolt cylinders
They are each pictured below:
Cylindrical Lock Cylinder
Cylindrical locks are one of the most common types of locks, but can be deceptively complicated to change. If this is the only lock on your apartment door, or if you want actual security, you might consider just leaving it alone and installing a deadbolt above it, since a cylindrical lock provides basically very little resistance to burglary.
Because of the great differences between cylindrical lock cylinders of different manufacturers and even between different product lines of the same manufacturer, it may not be feasible to purchase a replacement cylinder in advance unless you know the exact make and model of the lock. If you do not have a replacement cylinder in advance, you will have to leave the secured space open while you fetch a new cylinder or get the existing one rekeyed, so plan to have someone watch the space while you are gone.
Many manufacturers offer their cylindrical lock installation instructions online. If you identify your cylindrical lock make and model you may be able to find these instructions online.
Above right is shown a cylindrical key-in-knob lock. Below that is the latch face of a cylindrical lock, where you can usually find the brand name. Below this section is an illustration of a cylindrical key-in-lever lock.
To access the cylinder, you will need to remove the outside knob or lever. To do this, you will need a piece of stiff wire and the key to the lock. In the illustration below I have (rather crudely) indicated the location of the all-important poke hole. If you determine that your lock has no poke hole, that means that your lock is either cheap, old, or complicated to disassemble. Your best bet is to replace the whole lock.
If your lock indeed has a poke hole, to remove the outside knob or lever, insert the key and turn it 90 degrees. Depending on the lock function, this action may or may not retract the latch. With the key turned to 90 degrees, insert a piece of stiff wire or other slender, rigid object straight into the poke hole. Beneath the poke hole there is a pin which must be depressed in order to allow the lever or knob to slide off. This process would be easy if you had three hands. To remove the knob or lever, you must pull on the knob or lever while depressing the pin beneath the poke hole and turning the key to the 90 degree position. It should slide off with a small amount of force.
Once you have removed the knob or lever, look inside from the back. The cylinder should be loose inside the knob or lever, or held in by a piece of plastic or sheet metal. Remove whatever is holding it in and remove the cylinder. Now look on the latch face (visible on the edge of the door) for the brand name of the lock. Armed with the brand name of the lock and the cylinder, you should be able to bring the cylinder to a locksmith and either purchase a replacement cylinder or have the locksmith rekey the cylinder as an over the counter transaction.
Illustrated Cylindrical Lock
To avoid confusion, try to find installation instructions for your brand of deadbolt online. Like cylindrical locks, deadbolts often have their brand name stamped on the latch (or bolt) face (see picture of Arrow Latch Face above).
While tubular deadbolt cylinders can often be similar in appearance to cylindrical lock cylinders, they are usually much easier to get to. If the lock has a key on the outside and a thumbturn on the inside, simply unscrew screws until the lock comes off the door.
If the lock has a key inside and outside, the screws that hold the inside cylinder on are probably concealed. The usual way they are concealed is with drive-in covers, that is, screw covers that are tapped into place with a hammer. These screw covers are sometimes difficult to remove without damaging them. Some double keyed deadbolts have a shutter that turns when the inside key is turned. When you turn the key to a certain degree, holes appear which allow the lock to be removed. Once the lock is removed, the cylinder will be clearly visible.
The outside cylinder will be held into the outside housing with a clip or screw, or it will actually be the outside housing.
As with the cylindrical lock, you can usually look on the edge of the door where the bolt projects and find the brand name of the lock. Armed with the brand name of the lock and the cylinder in hand, you can take your cylinder to a locksmith for rekeying or replacement.
When you are at the locksmith shop, ask if it would be cheaper to rekey the lock or to replace the entire lock with an equal lock. The locksmith will probably express an opinion about the quality of the lock. Based on that opinion, you can decide whether you might want to upgrade to a better lock.
When you reassemble the lock, note that the tailpiece, that is, the piece of metal that connects the cylinder(s) to the bolt, is (are) "timed". That means that they must be rotated so that the tailpiece is free to turn when the bolt is thrown by the turnknob or other cylinder. Such tailpieces are called "lazy" tailpieces because they are passive, allowing themselves to be turned by an outside force. You will know that you did it wrong if you reassemble the lock and then find that you cannot lock or unlock it from one side or the other.
Mortise cylinders are much easier to deal with than cylindrical lock cylinders or tubular deadbolt cylinders, but there are still a couple of things you need to know in order to get one in advance, and those are:
- Cylinder length (dimension "X" in the illustration above left)
- Cam style (above right)
The cam pictured above is specific to Sargent mortise locks. Different manufacturers use different cams for different models of mortise locks. If you have the wrong cam, your cylinder will probably not work right.
You can take the mortise cylinder with you to the locksmith shop and tell the counter person that you want one just like it. Of course, while your cylinder is out of the lock, your door is not secure.
A mortise cylinder is actually a big machine screw. It theads into the body of the mortise lock. It is kept from turning by a set screw. To remove the mortise cylinder from a mortise lock:
- Remove the lock front, or faceplate, by removing the two faceplate scews as shown above right
- Loosen (but do not remove) the cylinder set screw (next picture down)
- Turn the mortise cylinder counter-clockwise until it comes out
To put the new mortise cylinder in:
- Thread the mortise cylinder clockwise into the lock body
- Tighten the cylinder set screw (DO NOT OVERTIGHTEN)
- Re-install the mortise lock faceplate
Rim Cylinders are the easiest of all cylinders to replace. For one thing, since there is very little difference between rim cylinders made by different manufacturers, you can just go buy one and it will probably work just fine.
To remove your old rim cylinder:
- Remove the lock from the door
- Remove the two screws that hold the rim cylinder in place
To install the new rim cylinder:
- Cut the tailpiece if necessary with a bolt cutter or hacksaw
- Fasten the rim cylinder screws through the cylinder backplate
- Re-install rim lock
Very easy. Cutting the tailpiece can be challenging if you've never done it before. Just be careful not to cut the tailpiece too short.
© 2008 Tom Rubenoff
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