Master Key System

[Urbex]

Thats why I only made the chart go to 18, no sense in posting more if it just going to be redone.

I hope it will be the final system, I may start cutting some keys tomorrow!

[linty]

that looks much better. If you keep going with that pattern you should have no problems. I am really not getting this "top" column though. Generally in standard locks you don't match the drivers height to the pin height. Don't get me wrong, it's great if you do, but if that's your goal then there are still some bugs to work out.

If you are matching tops and bottoms usually you first figure out what the recommended pin stack height is for the type of lock you are working with and try to compensate for the difference in bottom pin heights using the top pin heights.
The goal here is to ensure that the shear line is always blocked when the pins are at rest, and that the maximum compression on the spring isn't too strong. Also it increases the security of the lock, but I think that's advanced material.

Keep in mind that master pins are counted as bottom pins for these purposes because they contribute to how high the driver gets pushed up.

I'm not sure if I'm reading this right, but if you are using the same numbering convention throughout this system it looks like you are planning to use top pins that are only equal in length to two cuts. (so probably between .030 and .040 thousands).

Let's say you are using schlage, which has 10 valid cut depths (0-9) using factory specifications. If you use place #5 pin, a #2 master, and a #2 top into one chamber they would be equal in length to a #9 pin and still won't block the shear line when there is no key inserted. This is not acceptable with a pin tumbler since that chamber wouldn't stop the lock from turning even if there is no key inserted (although you'll wreck the spring).

Your pin stack MUST be tall enough to block the shear line when no key is inserted.

Generally you can usually get away with not matching top pins to bottom pins. You can use top pins between .0160 and .0180 in pretty much any but if you want to get technical about it, the top pin must be long enough that if you were to add it to the shortest pin they would still extend above the shear line. So again to use schlage as an example, shortest pin is .0165 and the shear line is (guessing here) .0310. Your top pin would have to be a at least .0155 to be sure the shear line is nicely blocked when no key is inserted.
If you use top pins that are too long you will have trouble putting the key in or taking it out because you are trying to compress the springs too much. You may find the key actually getting trapped in the cylinder.

The same rules apply if you really want to match tops with bottoms. The stack height must be such that when no key in inserted the top pin is blocking the shear line. Since cylinder springs are usually designed to operate effectively within a certain range you'd probably want your stack to extend at least .050 above the plug. Although a little more or less wouldn't hurt too much.

Let me know if you have any questions before you get started cutting keys. Or if you want to give out specifics regarding what types of locks you are working with we might be able to help a bit more. You may want to practice a bit with systems like this before you go out and set one up.

[Urbex]

I am really not getting this "top" column though. Generally in standard locks you don't match the drivers height to the pin height. Don't get me wrong, it's great if you do, but if that's your goal then there are still some bugs to work out.

Bottom pins 1, 2, and 3 use driver number 1 (.235).
Bottom pins 4, 5, and 6 use driver number 2 (.200).
Bottom pins 7, 8, and 9 use driver number 3 (.165).

Let me know if you have any questions before you get started cutting keys. Or if you want to give out specifics regarding what types of locks you are working with we might be able to help a bit more. You may want to practice a bit with systems like this before you go out and set one up.

I actually cut the first keys today, and used a spare mortise cylinder to demonstrate it. I pinned it for the change key and the master key, and it worked like butter. I was pretty proud of myself today!

I'm working with five pin Schlage "C" locks.

As fun as practice is, even if I mess up it won't be worse than what is in place now. Change keys were lost, so masters were given to replace them... a big mess.

Linty, you are a wealth of information!

[linty]

Excellent, glad to see I was wrong about your top pins. That should work quite well.

Let us know how this goes!