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Fig. 25
KEY MACHINE ACCURACY
Generation Cutting
Generation cutting is a process where the key machine operator takes a fresh cut key and duplicates another
key off of it, then takes that freshly cut key and duplicates another from it, and so on. The idea is to cut as many
“generations” as possible and still have a working key. This is interpreted as a “test” of the quality of the key ma-
chine.
What key machine operators often forget is if the depth adjustment is off by as little as 1-1/2 thousandths of an
inch (.0015”) they will accumulate generations. In as little as five generations the key probably won’t work in the
lock.
In reality, generation cutting is a representation of the entire key cutting process (key machine, operator, and
adjustments) and the results you get are either good or bad – but you don’t learn the reason why you are getting
good or bad results. Your results do not indicate the quality of the key machine, the
quality of the operator, or the quality of the adjustments made to the machine. All questions remain unan-
swered.
There is only one way to get good results on a consistent bases. Buy a quality-built heavy-duty key machine,
don’t abuse it, and keep it well maintained and adjusted at all times. Keep an eye on cutter sharpness, the in-
tegrity of the stylus, the fit of the vise jaws, the fit of the key gauge shaft to the carriage, and the fit of the cutter
shaft to the bearings. Any situations in these areas will decrease the performance and accuracy of the machine.
When parts start to wear – replace them.
In addition to a quality machine and its maintenance you need an accurate measuring tool such as a dial caliper
or key micrometer (preferably mechanical digital).
Measuring True Key Machine Accuracy
The proper way to measure key machine accuracy is to take the key you are going to duplicate from and meas-
ure it. Measure each cut from the back edge of the blade of the key. Measure each cut several times and rec-
ord their average. Compare the results. There is really no substitute for the procedure if you want to make ac-
curate duplicate keys. Generation cutting will not give you meaningful results like this procedure.
MOTOR MOUNTING SCREWS
