You could be using a "restricted keyway" that would ensure that you are the only source of the keys as a locksmith selling the same product line would be contractually required to check a signature card before duplicating the keys using that keyway... You might want to look into it in the future, as just about any key duplicating kiosk can order the Best keyways that are available from their competitors simply by looking it up in the Ilco book and ordering the quantity desired...
Correct, it is also better to have more secure exterior locks by not masterinig such doors to every key in the building to keep some amature theives outside rather than making extensively crosskeyed cylinders which are easier to pick the only thing keeping them out...
Because you are pinning extra keys into the lock... What I described would be making use of Incidental Master Keys (IMK's) that are already pinned into the lock... I will explain it below in more detail... I think that with only 40 doors you don't even need to have a GMK... You could have a single MK level and make use of IMK's to give each tenant their own master key for their sections of the building...
The more pins you introduce into your pin stacks the easier you make the IC to pick... So crosskeying should be kept to a minimum...
The point of installing and using SFIC's is not to have twice as many cores as you need but to re-pin them when you need to...
You will need to change high traffic cores and repin them periodically even if they are single keyed cores... Its the frequency of use that determines wear in the core, not the number of keys keyed into it... But by having a high traffic core keyed to one key you are no longer having to worry about thin #2 master pins falling out and making several keys stop working...
You could set up a 3 Step progression system if you only have
40 doors in your facility -- its just awkward to do the progression of the KBA and list the keys... It is a solution for worn mortise cylinders to get a little while longer without replacing the cylinders...Example of an IMK being used to give out a "sub-master" key...
TMK A 93(2)345 MK AA 73(2)345 MK AB 53(2)345
Suite 1
SubM 75(4)345 SubM 55(4)345
CK's AA-1 75(4)567 AB-1 55(4)567 AA-2 75(4)767 AB-2 55(4)767 AA-3 75(4)967 AB-3 55(4)967 AA-4 75(4)167 AB-4 55(4)167
SubM 75(6)345 SubM 55(6)345
AA-5 75(6)567 AB-5 55(6)567 AA-6 75(6)767 AB-6 55(6)767 AA-7 75(6)967 AB-7 55(6)967 AA-8 75(6)167 AB-8 55(6)167
SubM 75(8)345 SubM 55(8)345
AA-9 75(8)567 AB-9 55(8)567 AA-10 75(8)767 AB-10 55(8)767 AA-11 75(8)967 AB-11 55(8)967 AA-12 75(8)167 AB-12 55(8)167
SubM 75(0)345 SubM 55(0)345
AA-13 75(0)567 AB-13 55(0)567 AA-14 75(0)767 AB-14 55(0)767 AA-15 75(0)967 AB-15 55(0)967 AA-16 75(0)167 AB-16 55(0)167
It is a different way of providing SMALL master key groups without having to put extra pins in the cylinder by cutting keys differently... And I have never used more than ONE master pin in each chamber in the core...
The example I have provided above could be progressed into having as many as 64 different keys in each sub-group and still be under a higher level master key...
I honestly believe that given the size of your facility you could live with having a single MK that you keep for yourself and never issue to tenants and just cut them IMK's that share most of the cuts with the change keys you issue to them... After all you only need to have
40 keys at any one time and have a 6 pin IC which has a potential of 4,096 combinations...You weaken your system by introducing more levels of unneeded hierarchy to your masterkeying design...
It would be interesting to see your bitting charts to see exactly how you did things -- but I will understand if you don't want to post them here...
If I had more information about the layout of your building I could help you more...
Evan, ~~ formerly a maintenance man, now a college student...