Maison pinning a lock?

[Josh_Your_IT_Guy]

We have a handful of tenants who require access to a storage area. I would like to add a Maison keyed lock to this storage area to keep random people out, but allow the convenience of the tenants to use their own key.

I know it is basically a master keyed lock, but I am unsure of the "formula" to pin it correctly.

I also know that Maison keying degrades security, but this is a risk we take, as it is currently wide open for everyone.

If it matters, this is for a Schlage SC4 6-pin 9-depth system (not master-keyed).

[Squelchtone]

I think you have to start with the fact that the tenant's keys all have to share several key cuts, and then partially pin the storage area's door maison keyed cylinder to have those 2 or 3 pins, but I do not believe they have all 5 or 6 pin chambers pinned up, at least that how my last apartment building was for the front door.

Squelchtone

[Josh_Your_IT_Guy]

Ok, so knowing that all of our locks are pinned in all 6 chambers, and knowing the bitting, is it as simple as splitting the master pins between all of the cuts?

For example:
I have 3 random change keys with the following bittings:
633421
264421
635331

So, knowing those, and taking an example from Kwikset's rekeying manual, would this work?:
Smallest numbers from each cut for bottom pins: 233321
Difference between cuts 1 and 2: 431000
Difference between cuts 2 and 3: 431110
Difference between cuts 1 and 3: 002110
So, first layer of master pins: 231000
Second layer of master pins: 201010

That look correct?

[Josh_Your_IT_Guy]

Just re-read your reply.
So you think in my example, I could pin chamber 6 with a 1, chamber 5 with a bottom 2 and a master 1, and then say chamber 1 with a bottom 2 and a master 4, then leave the remaining chambers empty?

[Squelchtone]

Just re-read your reply.
So you think in my example, I could pin chamber 6 with a 1, chamber 5 with a bottom 2 and a master 1, and then say chamber 1 with a bottom 2 and a master 4, then leave the remaining chambers empty?

yes, but the security of that storage area becomes horrible. some keys may be able to be jiggled to get it to open, and picking or bumping would be a breeze. But this qualifies as a security through obscurity scenario, because most people walking up to the door either don't know or will assume it is fully pinned up.

I think I may be missing an important detail, and Im not sure what it is, perhaps some of our seasoned locksmith members can fill in the blanks and offer their experiences with maison keying.

Squelchtone

[cledry]

633421
264421
635331

The example pinning is incorrect. To maison key these you would use:

233321
43111x
xx1xxx

I would try and use a combination lock instead of maison keyed locks.

[cledry]

Why would you leave some chambers empty? Now any key combination in those empty chambers would work the lock.

[GWiens2001]

Don't think those are empty chambers. They look like the pins all across on the top, then each needed layer of master pins, making all possible key permutations in the allocated change keys.

Gordon

EDIT - just realized it was not somebody questioning your pinning, but you asking another question.

[Wiseman501]

+1 for the idea of a combination lock, and giving the combo to all of the right people. A lock pinned like you mention is far too easy to pick into if there is anything inside worth keeping, and a combination is easy to share. Plus, while combination locks CAN be "decoded", some of them take a very specific knowledge and quite a bit of time, meaning that your average crook is far less likely to try compromising it with any degree of success. I suggest that you do NOT use a combination lock with multiple wheels that display numbers. Those are usually FAR too easy to defeat unless you pony up a few more pieces of lettuce. Also try avoiding a lock susceptible to shimming at the shackle.

[Evan]

We have a handful of tenants who require access to a storage area. I would like to add a Maison keyed lock to this storage area to keep random people out, but allow the convenience of the tenants to use their own key.

I know it is basically a master keyed lock, but I am unsure of the "formula" to pin it correctly.

I also know that Maison keying degrades security, but this is a risk we take, as it is currently wide open for everyone.

If it matters, this is for a Schlage SC4 6-pin 9-depth system (not master-keyed).

You can only really provide for this sort of function when it is planned for at the inception of a keying system...

To come much later and try to add it in doesn't make much sense nor can you 100% guarantee against or prevent undesired key interchange...

I would key the storage room to its own key and provide copies to those people who require unsupervised access to the room...

~~ Evan

[globallockytoo]

I think you have to start with the fact that the tenant's keys all have to share several key cuts, and then partially pin the storage area's door maison keyed cylinder to have those 2 or 3 pins, but I do not believe they have all 5 or 6 pin chambers pinned up, at least that how my last apartment building was for the front door.

Squelchtone

Yes. That's right. Decode all the keys you want to work that lock and find the constants. Master pin the rest.

You dont need to concern yourself with pinning a compete new system from the start. But you need to be aware of interchange and ghost keys.

[Squelchtone]

I think you have to start with the fact that the tenant's keys all have to share several key cuts, and then partially pin the storage area's door maison keyed cylinder to have those 2 or 3 pins, but I do not believe they have all 5 or 6 pin chambers pinned up, at least that how my last apartment building was for the front door.

Squelchtone

Yes. That's right. Decode all the keys you want to work that lock and find the constants. Master pin the rest.

You dont need to concern yourself with pinning a compete new system from the start. But you need to be aware of interchange and ghost keys.

I like the term ghost key, is it too late to change my user name? =)

[peterwn]

Why would you leave some chambers empty? Now any key combination in those empty chambers would work the lock.

There are two issues here:
1. A master spacer that is one level thick is too thin for comfort. It could wedge between the plug and shell especially if the cylinder is worn or the plug excessively filed or it could flip on end. Two levels thick could be marginal.
2. Could be a tolerance problem with multiple spacers in one chamber.

Hence it is more expedient to omit some pins completely than to risk potential problems with having multiple and thin spacers.

An old locksmiths magazine suggested the following Maison system for re-keying worn cylinders.
Master 11154
Change keys 33354, 33554, 33754, 33954, 35353, etc to 99954 (27 differs or 81 differs with 6 pin cylinders).
Maison cylinder pinned xxx54 where xxx are empty chambers.

There was reference to a badly 'overworked' Maison system on the old alt.locksmithing newsgroup. It used 5 pin cylinders and covered 3 buildings. There was a GMK, a MK for each of the three buildings and a Maison cylinder for each of the three buildings. Goodness knows how this could be achieved while retaining some semblance of security.

I believe some Kaba cylinders come in two varieties with the pins in different positions. Change keys have two sets of cuts - a regular set and a second set for the Maison cylinder. The Maison cylinder has full security except that lost or stolen change keys will continue to fit it even if the relevant individual locks are changed.

[Robotnik]

When Maison keying a lock with empty chambers, it's possible to end up with a key that can be withdrawn before the pins reset when the key combines certain depths. In such a case, the next person walking up to that door could open it by simply turning the plug with a screwdriver. Just a word of caution based on some personal observation and use of unfortunate keying schemes

[peterwn]

When Maison keying a lock with empty chambers, it's possible to end up with a key that can be withdrawn before the pins reset when the key combines certain depths. In such a case, the next person walking up to that door could open it by simply turning the plug with a screwdriver. Just a word of caution based on some personal observation and use of unfortunate keying schemes

In the example I cited the author explained that the remaining two pins were at the rear to minimize wear on them and presumably if spacers are not used there and 'zero' cuts avoided the chance of the pins not resetting would be minimized.

With the advent of card access systems, there seems little reason to use Maison keying nowadays. While a card access system on the main entry door would cost significantly more than a Maison system, it overcomes the horrid issues associated with Maison keying including the disadvantage of not being able to 'block' lost keys. A separately keyed lock on the main entrance even with the slight inconvenience of residents having to carry a second key is a better option than Maison keying. This lock can be on a restricted profile to minimize key proliferation and residents charged a premium price for replacement or extra keys which can contribute to the cost of a re-key each several years.

It would also seem (especially in the USA context) that it is just too risky for a building owner or manager (and the insurers) to tolerate a Maison system. An accumulation of unaccounted for keys or an easily compromised Maison cylinder (even more so if worn) could expose the owner or manager to a multi-million claim if an intruder raped a resident or similar on the grounds that the owner or manager could have done better by installing card access at least on the main entrance.