by Romstar » 18 Aug 2004 17:29
In any given lock, the depths and spacings are a known quantity.
Normally reading a lock is associated with wafer and disc locks, but can be applied to pin tumbler locks.
Even in the Corbin and Medeco wedge type pins, they are known pin depths, and spacings.
Examine the first pin you can see. A lock scope is a great tool for this, but certainly not a necesity. A well lit area, or a small flash light is essential.
If you can see the shear line of the pin, you have a very seriously short pin. Most likely a 2. It's entirely unlikely that you would have such a short pin in the front of the lock, so now we have to examine the pins.
Drive the pin up into the cylinder, and see how far it goes. Excepting different length drivers, you should be able to estimate the size of that pin, and the corresponding key depth for it.
Continue on to the next pin. until you have done each of the pins. Use what you have discerned from pushing them all the way up, and guesstimate the depths of the pins. This gets much easier with practice and familiarity with the different lock types.
Another way to do this is by probing the lock with a wedge shaped feeler guage with a long tappered point.
Insert the guage all the way into the lock, and compress all the pins up into the cylinder. Then, ease off the guage until pin 5 drops. Keep the edge of the guage against the side of the pin, and you may find the shear line.
Probe with the gauge until you find a shear line. If a shear line is found, drive the tip of the gauge between the lower pin and the driver as far as it will go. Note the distance the gauge went in.
This will tell you the height of the lower pin based upon the depth of the gauge. The deeper the gauge goes between the pins, the shorter the pin, and consequently, the higher the key cut. The less the guage goes in, the longer the pin, and the deeper the key cut.
If you cannot find a shear line, you have a very long pin, and as a consequence, a very deep cut.
Based upon your knowledge of the lock in question, and it's known depths and spacings, you can estimate what each pin size is. This would allow you to attempt to cut a key, or enhance your ability to pick the lock for proper decoding.
Making a key using these methods is a great thing, but if you are dealing with a master-keyed lock, your best bet would be to pick, and disassemble the lock for decoding, and make a key based upon that information.
Good lock, and keep practicing.
Romstar
