In the example, space one cuts are MK/Cont =6 and CK cuts =8. In order to conserve change key cuts, spaces 1,2,5,6 normally have the same cuts on both the master key and control key. Sargent LFIC cylinders only have a control key housing in spaces 3 & 4. Finally, the total pin stack must equal 14. Since we already have '5' loaded into the bottom chamber, a '4' pin is required to reach '9' (9-5 = 4). The control key operates a second plug dia which is 6numbers higher than the control key cut (6+3 = 9). In the example, the chamber would contain '5' (4 + 1). Rules are identical to the A2 system for pinning the bottom and change key cuts. However, a few companies such as Arrow &, Best do make A4 system available for additions to old A4 system already in existence. Since the temporary pin stack is '10' (5+5 = 10), the top pin must be a '10' (16-10=6).Ī4 systems are also less popular today. Finally, the total pin stack must equal 16. Since we already have '5' loaded into the bottom chamber, a '5' pin is required to reach 10 (10-5 = 5). The control key operates a second plug dia which is 7 numbers higher than the control key cut (7+3 = 10). Pinning rules are identical to the A2 system for pinning the bottom and change key cuts. Since the temporary pin stack is 13 (8+5 = 13), the top pin must be a '10' (23-13=10).Ī3 systems were invented by Best Lock but they proved to be mechanically unpractical. Finally, the total pin stack must equal 23. Since we already have '5' loaded into the bottom chamber, an '8' pin is required to reach 13 (13-5 = 8). The control key operates a second plug dia which is 10 numbers higher than the control key cut (10+3 = 13). Therefore the total bottom pins loaded into the chamber would be '5' (4+1 = 5). The difference between cuts for the change key and master key is '4' (5-1 = 4). In our example, the highest cut between the change key and master key is '1'. Pin number totals in each chamber must total 23. American Lock, Arrow, Best, Master Lock, Peaks, Sargent, Schlage, Marks Hi Security & Scorpion/CX5 are among the companies offering cylinders pinned to an A2 key system. A 6-pin A2 master key system will generate 4096 change keys and every key combination can be used. The A2 SFIC system is very popular since there are no maximum adjacent cut problems. To simplify reading the charts, in most cases except as indicated, the master key cuts are 111111, control key cuts are 333333 and change key cuts are 555555. Missing from this list are Assa, Medeco and Peaks which require individual articles because of their complexity. The following charts show some of the mathematic rules for pinning popular SFIC and LFIC cylinders. In many cases a locksmith will be asked to rekey an interchangeable core cylinder he or she is not familiar with. Key blank heights from other lock manufacturers were too large to fit within the confines of the "Best" figure 8 core, so they designed a new breed of large format interchangeable core (LFIC) cylinders.Įach manufacturer who offers LFIC cylinders has their own cylinder design and their own cylinder pinning rules. This required a new series of key blade shapes. The small format interchangeable core (SFIC) system invented by Frank Best proved to be the most practical solution for fitting a removable cylinder into a 1 1/4" diameter hole.īecause of cylinder diameter restrictions, the key blank height also had to be reduced. There were other cylinder removal inventions but most were limited to mortise cylinders and involved removing the whole round cylinder while leaving only a thin shell in the door. Frank Best is usually recognized as the man who put interchangeable core on the map.
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