The first physical step in rekeying a cylinder is to remove it from the lock body, knob or lever. In a mortise lock this is accomplished by loosening the set screw that holds the cylinder into place, and unscrewing the cylinder. In a key-in-knob or key-in-lever lock this is usually accomplished by using the currently operating key and a pointed tool, a pick, or a probe. The key is turned 90 degrees, and a detent can then be pressed in, allowing the knob or lever to be pulled off, exposing the cylinder for removal.

In this case we are using a Schlage knob / lever cylinder for demonstration. With the key removed from the cylinder, the small spring loaded pin at the back of the cylinder can be gently depressed, and the brass cap unscrewed. The cap, tailpiece, retaining pin and its spring can be set aside. Many other brands use a simple C clip at the back of the cylinder instead of the screw on cap arrangement.

From here on, caution must be used to not 'blow the cylinder up' (accidentally allowing the springs and pins to launch out of the plug), or to allow the plug to get jammed by pulling it partially out, and letting the top pins drop into the wrong chamber of the plug. The current key is inserted into the cylinder plug, rotated 90 degrees or so, and with the follower tool held firmly against the back of the plug, the plug is slid out of the cylinder shell, with the follower occupying the plugs normal place in the shell. The follower keeps the top driver pins and springs in place. No gap can be allowed between follower and plug when sliding the plug into or out of the shell.

Now that the plug has been extracted the old tumblers can be dumped out. The tumblers are expendable, no attempt should be made to reuse them. The plug emptied, it can be checked for any damage or excessive wear, and set aside. Next, carefully manipulating the follower and the cylinder shell with one hand, and a pair of pin tweezers with the other hand, the driver pins and any master pins are removed from the shell. The driver pins are often just left in place and reused, but for proper rekeying the driver pin lengths are supposed to correspond in length to the new bottom pins that will go into the plug. A shallow cut on the key uses a short pin, the corresponding driver pin should be longer, resulting in a consistant 'stack height' (the combined height of all the pins in the chamber) After carefully inserting the new top driver pins back into the cylinder shell, attention is turned to the plug.

Since we are using a Schlage cylinder, we need only use a pin kit that contains the Schlage tumblers only. A Universal pin kit containing all of the various pin sizes can have a hundred compartments or more. Using a Schlage only kit reduces this to 18 pin compartments, making for a much more portable kit, and speeds up rekeying. To make things even easier, the original Schlage keys being used to set the cylinder up have the cut numbers stamped into the bow of the key. The new bottom pins are loaded in, point down, flat end up, and the plug visually checked. The tumblers should be level with the plug surface. WIth everything lining up fine, the plug can be slid back into the cylinder shell, in the same 90 degree rotated position in which it was removed. The cylinder can be carefully checked for smooth operation, being careful not to pull it back out, as the retaining cap is not in place yet.

Finally, with the key removed, the retaining spring and pin are put back into place, and the cap gently screwed on while the pin is being gently held down, same as when it was removed. The cap gets screwed on barely finger tip tight, then backed out a notch or two. The pin should lock into place in one of the notches on the cap. You know it is in the correct position if the key turns easily, and the key can be easily removed from the cylinder. If it is too tight the key will be hard to turn. If it is to loose the key will be difficult or impossible to remove. The cylinder is now reinserted into the lock and checked for operation. This one is done.

    This image shows how everything would be aligned when the correct key is inserted. The plug can rotate freely since all the tumblers will match with the shear line.