HOW TO PICK A LOCK:  Lockpicking, OR Lock Picking HOW TUMBLERS WORK
What happens when you insert a correctly cut key into a lock?  To illustrate this, let's simplify a lock by removing all but one set of pin tumblers (wafer locks function in a very similar manner).  In fact, this is an excellent tool for initial picking practice and you can order 2, 3 and 5 pinned cylinders from Lockpicker's Mall for this very purpose. Once you understand what happens in one chamber, just multiply that by five times, realizing that in each chamber the pin sizes will be different but the action will be the same.  By practicing picking with cylinders First, realize that a basic
1.  The plug -  A cylinder usually made of solid brass or steel in which a keyway has been formed.  Along the top of this smooth plug, in a straight line from front to back, you'll find a series of tiny drilled holes, just a fraction larger in diameter than the pin tumblers that will drop down into them.  At the rear end of the plug will be some kind of cam or tailpiece that will mate with the lock mechanism or the latch itself, so that when the plug is rotated the lock will open. - 2.  The shell -  This can be simply a tube made of brass with a pin chamber, or bible, attached (illustration to right), or it can be a piece of solid brass or steel bored to accept the plug.  In either  case, a chamber sits atop the shell that contains the pin stacks and driver springs.  The shell and plug together form the lock cylinder. -
Refer to the illustration below.  In the locked position, with no key inserted at all, the bottom pin rests completely within the space of the lock plug, with the top pin pressing down against it, driven by the driver spring.
You can easily see how, even with only this one pin stack having dropped into the shear line, the plug would not be able to rotate within its cylinder.  The top pin has "pinned" the lock in place.  The illustration here shows only one pin chamber.  With five of them similarly loaded, no amount of turning force would ever defeat the action of the five top pins holding the plug in place!  Now consider what happens if the wrong key is inserted: Here I've added another pin chamber to illustrate that an incorrectly cut key will defeat itself by either raising the bottom pin up into the shear line, as in the first chamber,   With tumblers that are correct for the key bittings, the top and bottom pins meet exactly at the shear line, allowing the plug to rotate. GO TO NEXT PAGE OF LOCKPICKING TUTORIAL