Change a Lock Cylinder

Removable core lock cylinders or "Interchangeable Cores" are used primarily in commercial hardware, and have the advantage of being easily swapped for a replacement when keying needs to be changed. The exact process may vary among manufacturers, but most are changed with a special key. This article will show you how to use the key, from start to finish, with pictures along the way.

Steps

 * 1) [[Image:06 27 08_1335_47.jpg|thumb|The "core key" looks similar to any other key that would fit into the lock. Some have a longer length or special protrusion to actuate the release mechanism.]]Obtain or locate the "core key". A core key is like a master key, but rather than unlocking doors and locks, it allows the withdrawal of the core or cylinder from the lock housing itself.  Core keys will not unlock anything by themselves, but will make it possible to unlock a device without the need for a key.  A simple screwdriver is all that is usually needed to open a lock that does not have a core.  It should be evident that core keys need to be safeguarded similar to master keys.
 * 2) [[Image:06 27 08_1337_415.jpg|thumb|The core key in the "locked" position.]]Insert the core key into the core as you would with any other key. This is the "locked" position.
 * 3) [[Image:06 27 08_1338_428.jpg|thumb|The core key shown in the fully turned or "unlocked" position. Notice that it can only be turned only a very small amount.]]Turn the key.  It will only turn about 10 degrees.  Do not attempt to force the key further.  This releases the core from the lock housing.
 * 4) [[Image:06 27 08_1339_690.jpg|thumb|The core will easily slip out of the housing attached to the key in the "locked" position.]]Withdraw the turned key slowly from the lock. The core will pull out of the housing as the key is withdrawn position.  If the key is turned back to the locked position before withdrawing, only the key will be removed.
 * 5) [[Image:06 27 08_1341_265.jpg|thumb|The old core, key and link (top) and new core (bottom).]]Place the core with the key still inserted, next to the new core. The cores will most likely look very similar and keeping the key in one will help differentiate between the two.
 * 6) [[Image:06 27 08_1342_738.jpg|thumb| The link is removed from the old core and lays next to the old core.]] [[Image:06 27 08_1343_953.jpg|thumb| The link is now installed on the new core.]]Inspect the cores. Many times they will look identical, other times they will not.  It is these times that particular attention be paid.  The difference most likely will be that the "link" between the core and bolt will be still attached to the old core.  The link is a part that transfers the the rotating motion of the core to the dead bolt or latch mechanism (it usually consists of a piece of flat metal and or pins that attaches to the rear of the core). If this is the case, simply remove it from the old core and insert on the new core.   If the cores look the same, the link will either be in the lock housing or it fell off some time after the core was removed.  Verify the the link is indeed still in the lock.  Ensure that link will line up with the core by visualizing the core aligning with the link.  Nudge or adjust the link as needed with a screwdriver or needle-nose pliers.
 * 7) Remove the core key from the old core by holding the core in one hand and turning the key back to the locked position with the other hand.
 * 8) Insert the core key into the new core and turn to the "unlocked" position.
 * 9) [[Image:06 27 08_1344_16.jpg|thumb|The core is about to be slipped into the housing.]]Bring the core with the key inserted to the lock housing. Align and fully insert into the lock housing.  A core that can not be fully inserted indicates that there is misalignment of the link between the lock and core.  Adjust it to allow mating between these components and try again.
 * 10) [[Image:06 27 08_1347_561.jpg|thumb|With the core key returned to the "locked" position, the core is securely held in the housing.]]Turn the core key back to the locked position. The core is now secured in the lock housing.
 * 11) [[Image:06 27 08_1348_851.jpg|thumb|The core will remain in the housing while the core key is withdrawn from it, but only if the key is in the "locked" position.]]Withdraw the core key and verify proper operation of the lock and associated key(s).

Tips

 * If the regular key(s) are able to turn the core, but the lock will not open, the link is most likely missing from the lock and will have to be located and reinstalled.
 * As stated in the introduction, this is not the only way to change a lock cylinder. If you know of another way to do it, feel free to edit this article and share your expertise.

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