Unlike other commercial lock cylinders, figure-eight (small format) interchangeable cores require special removal techniques when keys are not available. Interchangeable cores are normally removed by inserting the control key then turning the key clockwise about 15 degrees. When the rotation...
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Unlike other commercial lock cylinders, figure-eight (small format) interchangeable cores require special removal techniques when keys are not available.
Interchangeable cores are normally removed by inserting the control key then turning the key clockwise about 15 degrees. When the rotation stops, the core is ready for removal by pulling it out of the cylinder, knob, lever, etc. Without a control key, the core is completely locked.
To rekey the lock or lock cylinder, the core must be removed. If the rekey job entails one lock, removal options are: to drill out the core or housing and replace it with a new one; or to pick the control level (shear line) of the core.
If rekey job consists of many locks using the same control key, the options are: to sacrifice one lock or lock cylinder to remove a core and decode the control key; to pick the control level of the core.
Picking Figure-Eight Interchangeable Cores
Figure-eight interchangeable cores can be difficult and time-consuming to pick, especially seven-pin cores. The locks have two different shear lines, the operating level that allows the lock to be accessed, and the control level that allows the core to be pulled from the lock.
If you don’t optimize your picking technique you will almost always pick the operating level. The primary reason why operating levels are easier to pick than control levels is the rotation of the operating level offers less resistance than the control level. Often control levels are difficult to rotate.
To facilitate consistent control-level picking, two techniques that can be used: applying pressure to the control lug or shell; or inhibiting the ability for the operating shear line to be picked.
Tension bars that grab the bottom portion of control shells can be made or purchased.
In Figure 2, the tension bar is inserted into the core and positioned until it drops into access holes at the bottom of the control shell. Unlike other tension bars, the handle is directed upward so that a better “bite” can be applied to the shell. When the tension bar is properly positioned, a greater amount of pressure is applied increasing the chances that the control level will be picked.
Another technique is to get pressure onto the control lug that protrudes on the left of the control shell. This is done by carefully drilling a small hole (3/32” drill bit) to the control lug. This requires checking the depth of the hole many times to make sure the hole is bored through the cylinder and barely touches the lug.
The hole is drilled on a slight angle so pressure can be applied to the lug with a pin extractor tool. Figure 3 shows the location of the hole.
Figure 4 reveals the picking technique. The pin extractor is firmly pushed up against the control lug. The extractor takes the place of the tension bar.
Once the core is removed, the hole on the face can be plugged with brass stock and filed smooth.
My personal picking technique is to inhibit the ability for the core to be picked to the operating level. Most of my time picking these cores relates to those that are master keyed and this technique is limited to master keyed cores. Fortunately most cores are master keyed.
Key blanks are milled across to what would be seven cuts. A key blank is needed for each keyway. The heads are also milled away (or cut off) to allow a pick to be inserted into the core. The milled key blank acts as an effective tension bar while inhibiting the core from being picked on the operating level.
What makes this occur is the fact that the largest bottom segment used in properly master keyed cores is a #7 segment. Pushing the altered key blank into the core can raise a few of the pin stacks to levels that bar the operating level while increasing the chance that at least one stack will directly align with the control shear line.
Insert the pick all the way into the core and work back-to-front, using more back-and-forth action versus up-and-down action.