More than 1 master pin in a chamber?

[Mr_Bones]

In a master key system with multiple groups, is it possible for there to be 2 or more master wafers in a stack?

[kwoswalt99-]

Yes, very possible. Quite common actually. Most sfic's have more than one in every stack.

[Squelchtone]

In a master key system with multiple groups, is it possible for there to be 2 or more master wafers in a stack?

totally. check out the 5th pic here: http://www.lockpicking101.com/viewtopic.php?f=9&t=59275

[Evan]

The real answer is no.

Having more than one "master pin" in a stack to allow additional cuts to operate at the plug shear line is called "double pinning" and is considered bad technique and an indicator that someone who shouldn't be master keying was working out of their depth.

Now there are some exceptions to this in special situations:

In some systems with selective master keys having the additional selective master key(s) operate a cylinder may require double pinning.

Cross keying where the additional master pin(s) allow additional change key bittings to operate (must be used carefully).

With SFIC's there is usually only one "master pin" as the third pin up from the key is called the "control pin" and establishes the bitting for the control function to operate and the upper most pin is called the "build up pin" to total the stack out at 23 increments in the A2 bitting system.

In Master Ring Cylinders it is again like SFIC's where there may be a "master pin" at the plug shear line to allow an additional change key to operate at the plug, above that is called a "build up pin" which could have a "master pin" above it if there are several master keys which will operate and the uppermost pin is called the "top pin" just like in a standard non-master keyed cylinder.

~~ Evan

[Squelchtone]

The real answer is no.

Having more than one "master pin" in a stack to allow additional cuts to operate at the plug shear line is called "double pinning" and is considered bad technique and an indicator that someone who shouldn't be master keying was working out of their depth.

Now there are some exceptions to this in special situations:

In some systems with selective master keys having the additional selective master key(s) operate a cylinder may require double pinning.

Cross keying where the additional master pin(s) allow additional change key bittings to operate (must be used carefully).

With SFIC's there is usually only one "master pin" as the third pin up from the key is called the "control pin" and establishes the bitting for the control function to operate and the upper most pin is called the "build up pin" to total the stack out at 23 increments in the A2 bitting system.

In Master Ring Cylinders it is again like SFIC's where there may be a "master pin" at the plug shear line to allow an additional change key to operate at the plug, above that is called a "build up pin" which could have a "master pin" above it if there are several master keys which will operate and the uppermost pin is called the "top pin" just like in a standard non-master keyed cylinder.

~~ Evan

So in my reply, I linked to an SFIC lock in my link, which I realize has different sets of rules and things like build up pins in the equation, but riddle me this, I have a Medeco system at work, where we have the following order: grand master, building master, floor master, change key for individual office doors. Are different stacks responsible for these functions, or do all 6 stacks have multiple master wafers in them in order to provide the bitting for each of the above listed keys? I understand the threat of sloppy pinning leading to cross keying, but I trust the locksmiths who installed this for us back years ago. Am I understanding correctly that more than likely if I were to take one of my Medeco mortise cylinders apart, only 1 or 2 stacks would have multiple master wafers in them while the other pins stacks would be pinned up for just the GMK and change key, but not the building or floor masters?, and I guess Medeco may be a bad example to answer the OPs question since Medeco has the whole fore aft biaxial thing going on with it.

Thanks
Squelchtone

[peterwn]

So in my reply, I linked to an SFIC lock in my link, which I realize has different sets of rules and things like build up pins in the equation, but riddle me this, I have a Medeco system at work, where we have the following order: grand master, building master, floor master, change key for individual office doors. Are different stacks responsible for these functions, or do all 6 stacks have multiple master wafers in them in order to provide the bitting for each of the above listed keys? I understand the threat of sloppy pinning leading to cross keying, but I trust the locksmiths who installed this for us back years ago. Am I understanding correctly that more than likely if I were to take one of my Medeco mortise cylinders apart, only 1 or 2 stacks would have multiple master wafers in them while the other pins stacks would be pinned up for just the GMK and change key, but not the building or floor masters?, and I guess Medeco may be a bad example to answer the OPs question since Medeco has the whole fore aft biaxial thing going on with it.

Thanks
Squelchtone

I read somewhere (ex Billy Edwards?) that Yale's original grand masterkeyed cylinders used double pinning. As Yale got more proficient with the art of masterkeying they no doubt would have reserved say two chambers for the sub masterkeys and the rest for change keys. A 6 pin GMK cylinder with one wafer in each chamber would have 61 incidental masterkeys (plus the 3 legitimate keys 64 in all). With double pinning in all chambers there would be 726 incidental masterkeys (plus 3 legitimate keys 729 in all). This alone indicates it is a 'no brainer' to try and avoid double pinning if possible especially as double pinning would significantly reduce the number of available legitimate differs. In this regard I cannot see why Medeco cylinders would be any different from ordinary cylinders. However with Medeco, a method of grand masterkeying (I am guessing here) could be that the same depths/angles are used for for each sub masterkey but with different permutations of fore's and aft's (assuming biaxial), with the grand masterkey containing both fore and aft cuts for each chamber. No doubt there are other ways of grand masterkeying these such as using profiles or change keys under one sub masterkey having same depths/angles but different fore/ aft selections. There is a problem with biaxial as I see it in that a key with say a fore cut only could in the wrong cylinder lift an aft pin of the same angle to the shear line - this would need to be considered when laying out systems.

Perhaps locksmiths may not always do the right thing and take shortcuts such as filing the plug so 0 or 1 (say) operates without a wafer, leaving chambers empty in Maison cylinders or choosing combinations out of thin air when re-keying or adding new cylinders etc.

[Evan]

So in my reply, I linked to an SFIC lock in my link, which I realize has different sets of rules and things like build up pins in the equation, but riddle me this, I have a Medeco system at work, where we have the following order: grand master, building master, floor master, change key for individual office doors. Are different stacks responsible for these functions, or do all 6 stacks have multiple master wafers in them in order to provide the bitting for each of the above listed keys? I understand the threat of sloppy pinning leading to cross keying, but I trust the locksmiths who installed this for us back years ago. Am I understanding correctly that more than likely if I were to take one of my Medeco mortise cylinders apart, only 1 or 2 stacks would have multiple master wafers in them while the other pins stacks would be pinned up for just the GMK and change key, but not the building or floor masters?, and I guess Medeco may be a bad example to answer the OPs question since Medeco has the whole fore aft biaxial thing going on with it.

Thanks
Squelchtone

Without knowing more specifics about the keying system in question I can not know for certain. I would need to understand how many keys there are at each level of the hierarchy. There is only one "top master key" which in your case is called the "grandmaster", but how many "building master keys" exist ? How many floors in the biggest building (this determines how many "floor master keys" the system can support under each "building master key") ? How many "change keys" under each "floor master key" ?

So master keying in general works like this:

After you have selected an appropriate master key bitting (I have discussed this before in other threads) you then need to determine the number of keying levels you would need within your system. You would then divide your key.

Take a six-pin key: ABCDEF

In a simple two-level master key system, all chambers would be used to progress change keys.
1 master key group of 4,096 change keys.

If you wanted a three-level master key system, you would have to choose one or more chamber to progress master key groups.

- If you used chamber A to progress master keys and BCDEF to progress change keys your system would have:
1 GMK with 4 master key groups of 1,024 possible change keys in each group.

- If you used chambers A and B to progress master keys and CDEF to progress change keys your system would have:
1 GMK with 16 master key groups of 256 possible change keys in each group.

- If you used chambers A, B and C to progress master keys and DEF to progress change keys your system would have:
1 GMK with 64 master key groups of 64 possible change keys in each group.

If you wanted a four-level master key system, you have to divide the key into more pieces.

- If you used chamber A to progress GMK's and chamber B to progress master keys and CDEF to progress change keys your system would have:
1 GGMK with 4 GMK groups each with 4 master key groups of 256 change keys in each group.

- If you used chamber A to progress GMK's and chambers BC to progress master keys and DEF to progress change keys your system would have:
1 GGMK with 4 GMK groups each with 16 master key groups of 64 change keys in each group.

But wait !! My system won't fit into this sort of pattern.

Say I need a system where each building in my complex needs a master key which will open all doors in each building but not in any of the others and each floor would have its own master key which will open all doors on that floor but no other. There are six buildings which have three floors in each building in my complex. Each floor has about 500 keyed doors on it.

Well let's look at this, we would need five chambers to progress 500 possible change keys per floor, one chamber to progress 3 floor master keys per building and two chambers to progress 6 buildings. Got an eight-pin lock cylinder ? No, me either. So how to accomplish our needs then ?

- You could use master-ring cylinders to accomplish this system but that might require replacing all of the currently installed door hardware.
- You could use a multiplex keyway family of cylinders to add to the keying system capacity.
- You could ask what high-security keying system options might be able to fulfill the specified system.

Since this is basic master keying we will go with a multiplex keyway keying system.

We need a keyway family that has more than six individual keyways.

Let's use the Corbin-Russwin "H" family. The top master key will be on the all section keyblank.

Key section "H1" will be building 1.
Key section "H2" will be building 2.
Key section "H3" will be building 3.
Key section "H4" will be building 4.
Key section "H5" will be building 5.
Key section "H6" will be building 6.

We now need 3 floor master keys in each building and 500 change keys per floor.

We will use chamber A to progress master keys and BCDEF to progress change keys your system would have:
1 GMK with 4 master key groups of 1,024 possible change keys in each group.

top master key = GGMK (on all section key blank)
building master key for building 1 = GGMK on key section blank "H1"
building master key for building 2 = GGMK on key section blank "H2"
building master key for building 3 = GGMK on key section blank "H3"
building master key for building 4 = GGMK on key section blank "H4"
building master key for building 5 = GGMK on key section blank "H5"
building master key for building 6 = GGMK on key section blank "H6"

floor master keys and change keys for each building are cut on that building's key blank.

We have found a way to use what we know about various locks and the rules for keying them to determine a proper way to create a master key system given the specifications.

~~ Evan

[Sinifar]

Cross keying is a difficult subject to broach. It takes careful planning to do this right, and you need to either find on your computer sheet close combinations to keep others out, or work the keying in as you go. This should be brought up at the keying meeting. Keep the cross keys to a minimum.

Another problem is wafering up a lock. Too often you end up with a stack which need say 3 - 5- 7 - 9. This means you need a stack of .030 (typical) MK pins - this tends with duplicates to get "nicked" on the pins and they tend to sick in the bible. The solution is to just have an empty chamber for that position and avoid the wafer problem - of course you need pins in the lock so here again expertise in MK work is needed.

If you really want to get into a major cross keyed situation, then look into "Pathfinder" keying. No I won't delineate this in this forum. this is a major cross key project which should only be undertaken by an expert due to all the complex problem which can arise from the extensive work. Trust me it works and well for up to 30 keys if done correctly.

Sinifar RL CMCL