SFIC control key bitting

[demux]

So most of you that have read my previous posts know that I like to work on SFIC systems both as a personal hobby and semi-professionally, and I've been wondering recently about the best way to specify a control key bitting. I've seen documentation/recommendations that says the control key should be cut as a normal change key in the system, and that bitting should just be excluded from the normal system progression. I've also seen documentation/recommendations that the control key should be completely outside the system bitting array, and should change even/odd parity in some if not all chambers (at least for the A2 system where parity matters). I've run across real-world systems (those not made by me) that do it both ways.

My question for the group, especially those of you that do this professionally, is is either way more correct than the other? When you're designing an SFIC system for a customer, which method do you use (or if you just click the "Generate" button in your software package of choice, which method does it use)? Or is it just a matter of personal preference?

Personally the "outside the system" approach seems safer to me as it reduces the chances that the control key bitting might be inadvertently assigned by some less-than-careful system expansion in the future, but if there's something I'm not thinking of in doing it that way, I'd like to hear about it. I can also see the case for the "normal change key that is excluded" approach in a large master key system where every chamber is mastered, as it would reduce the chances of key/lock wear turning an operating key into a control key. (Though I have not seen many SFIC systems that large where every chamber is mastered.)

Thanks.

[Squelchtone]

I'm gonna move this to Locksmith Business - Master Keyed Systems for ya, I think it's a better fit for those who may find the thread in the future.
-Squelchtone

[demux]

I'm gonna move this to Locksmith Business - Master Keyed Systems for ya, I think it's a better fit for those who may find the thread in the future.
-Squelchtone

Thanks Squelch. I was considering that one as well, but went for Locks instead since not all SFIC cores are necessarily mastered.

Seems like there have been a few other threads recently that fall into a similar gray area, would it perhaps be worthwhile having a dedicated "Keys" forum under Locksmith Business for things like bittings, blanks, profiles, etc? Not sure if that would be too specific for this board, but then again we have a whole forum dedicated to "Closers and Crash Bars", and it seems like there are a lot more questions about the former than the latter. Just a thought...

[Tyler J. Thomas]

Oh goodness, where to start. This is one of the most contentious questions in the industry if you pose it to people that are at least vaguely familiar with how things are done.

The short answer is that, with fully knowing system specifications, there is not a single answer that trumps the rest with regards to A2 systems - and as ambiguous of a statement as that is I promise you that if you put it in front of some people they'll even argue about that. All things equal, not everyone chooses to go about it in the same way. If you want proof of that then consider that different manufacturers use their own rules for selecting a proper control key; Falcon has a unique way of creating their own control keys that is different from BEST, for example. You are right, however, in that both methods you suggest are and have been used for quite some time.

My only suggestion with altering the parity between the control key and the rest of the system is that if you are not careful with your selection you may end up with change keys that that result in a core being combinated (on paper at least) and calling for a 1 master pin. Of course, a 1 master pin does not exist in an A2 system so those keys cannot be used.

An example being the following cut in the same position for each of the typical keys in a master key system:

Control- 0
Master- 9
Change- 1

A2 pinning rules would combinate the chamber as follows:

Top- 13
Build-Up- 1
Master- 8
Bottom- 1

See the potential problems?

This is a very fine line for me to tote in a public forum for me, personally, so I hesitate in discussing the whats and the whys with each method because of how the information could potentially be used. I would suggest reading Billy B. Edward's "Master Keying by the Numbers" or "Fundamentals of Master Keying" by Jerome Andrews - both tackle this issue very well in their book.

[demux]

My only suggestion with altering the parity between the control key and the rest of the system is that if you are not careful with your selection you may end up with change keys that that result in a core being combinated (on paper at least) and calling for a 1 master pin. Of course, a 1 master pin does not exist in an A2 system so those keys cannot be used.

An example being the following cut in the same position for each of the typical keys in a master key system:

Control- 0
Master- 9
Change- 1

A2 pinning rules would combinate the chamber as follows:

Top- 13
Build-Up- 1
Master- 8
Bottom- 1

See the potential problems?

Yep. I've got a little script I wrote some time ago to calculate bittings for SFIC systems, it's got a condition check in it to warn specifically for that situation. I've had one or two times I haven't been quite careful enough with my bitting selections and I've had to tweak the control in one of the chambers as a result of that check.

[Sinifar]

#1 rule I learned at Best was not to use the same bitting for the control as well as the operating keys.

So - if your key to operate is 4729431

Your control should be - 725464

That way there is no chance of the operating key working the control shear line. Now if you master key on the control, that is another matter entirely. not for this forum, a bit advanced.

Sinifar

[lorenzolrom]

An example being the following cut in the same position for each of the typical keys in a master key system:

Control- 0
Master- 9
Change- 1

As far as I can tell this is the only instance where you wouldn't be able to combinate, any other combination of mismatched CTs and operatings will work.