Modified Cylinder Rekey System

[Raymond]

Way before Kwikset Smartkey and Falcon Instakey were developed I made a couple of these locks that can be rekeyed without disassembly and restored at will. I would like to share this idea with whoever can use it. The next time I am making one I will take some pictures.

Purpose:
This lock was developed to solve the problem of being able to temporarily lock out one or more keys to a mortise lock cylinder while having the remaining key (or keys) continue to operate normally and to be able to reverse the process without the necessity of rekeying the lock each time.

Possible Uses:
An employer can allow or deny access at a specific lock and to one or more specific employees at
any time. When set up correctly this system will allow the first person to use the lock the ability to
lock other users out until reset. This system provides the user the equivalent action of rekeying this
lock either temporarily or until intentionally reversed. Library research, laboratories, evidence, tool,
photo-dark, or any rooms temporarily assigned to one person. The first person to enter can lock the
others out. The boss can open the door in the morning and lock it at night. During the day all
employees can come and go, but they are locked out after the boss stores the master wafers in
position 2. The boss can leave the lock accessible one day a week for after hour deliveries.
The boss can leave the lock accessible only one day a week for the cleaning crew. A small apartment manager can "rekey" the lock or lock out the tenant at will.


Construction:
I have adapted a standard brass mortise cylinder of the type and quality that has no hollow spaces in the body of the cylinder. In this example I have used only a five pin cylinder. A six-pin cylinder can be used just the same and will provide more change keys. I drilled five* new upper pin and spring chambers at an angle of about thirty degrees from vertical and perpendicular to the tangent of the lock plug. I used a center drill to start the holes more accurately. I established the proper spacing by use of a calibrated and moveable drill press table. The final holes were cut with a #31 drill. I then milled a shallow, flat groove along the top of the cylinder. (Very short allen screws can be used in each hole as spring retainers.) I pressed a flat strip of brass into this groove as the spring retainer as is common in many mortise cylinders. I removed the drilling burrs from the inside of the cylinder with a 45-caliber gun cleaning brush.


SAMPLE Keying and setup:
I proceeded to key the system with only two master wafers in the fourth and fifth pin chambers as demonstrated with the following pinning chart: bottom pin and (master wafer)
5 5 1 1(5) 3(5)

I cut the keys as follows:
Key A 5 5 1 6 3
Key B 5 5 1 1 8
Low Master key 5 5 1 6 8
High Master key 5 5 1 1 3

The normal, vertical upper pin chambers are designated as position 1 and the new 30-degree offset upper pin chambers are designated as position 2. All bottom pins and master wafers are loaded into position 1. Both positions are loaded with top pins and springs. (Note: Because of the shorter upper pin chambers, be sure to use the shortest top pin possible and balance the stack heights. This will minimize crushing of the springs in position 2.)


Usage:
With all bottom pins and master wafers in position 1, all four keys will operate. The High Master will continue to operate at all times. The low master key is used and turned to position 2 and removed. All master wafers are now moved into position 2.

If: The master key is inserted in position 2 and removed in position 1, all master wafers will be left in position 2 and the Low Master Key, Key A and Key B will all be locked out.
If: Key A is inserted in position 2 and removed in position 1, only Key A and the High Master will operate.
If: Key B is inserted in position 2 and removed in position 1, only Key B and the High Master will operate.

*In situations where you wish to restrict usage of the change from one key to another, do not drill the fifth upper pin chamber. All user keys will not be removable in position 2 if the fifth cut on the key has a high tip. The Low Master and High Master and a set of Key A and Key B keys will have the tip cut down level to the height of the fifth bottom pin and will slide smoothly from under the fifth bottom pin. Using this controlled changing will lower the number of usable keys to only 6 as the master wafer in space #5 is eliminated.

Additional Considerations:
In a five-pin lock, using one master wafer (two-step progression) in each of the five spaces, but using no more than two master wafers at a time, there are only ten possible, yet usable, combinations. Although there are actually 32 possible key combinations, these sub-masters would be difficult to use as they would work or not work as each change key is allowed or not allowed.

Making and using a set of change keys will allow the person in control to allow or disallow any combination of the ten user keys to operate. This would require the controller to use the High Master and each user key to move the corresponding master wafer to the position where it can be used. Make a user change key by cutting High Master cuts in all but one space and one change key cut in that space. Make a separate user change key for each space.

[Evan]

Hello Raymond:

What you are describing above is what is called a Lockout Cylinder in the industry...

They are typically not intended to be master keyed as if you insert the keys too quickly while turning the cylinder you will lose master pins in the in the upper chambers at the lockout position and it is possible that none of your keys will work and you will have a total and unintended lockout...

The way the locks work is more of how the keys are modified to allow or disallow lockout operation... In a six pin lock only four of the chambers would have upper chambers with pins in them at the lockout position... The remaining two positions have no upper chambers in the lockout position... This totally prevents full insertion and therefore operation of the lock using (non-modified) standard operating keys issued to those who can be locked out by someone in possession of a lockout key...

The lockout keys are modified in the last two bitting positions near the tip of the key, the slopes/notches/steeples of the key are removed in the last two positions so that you have flat bittings at the appropriate depth for the keying of the cylinder... Without those last two slopes/notches/steeples and the flat bittings instead the lockout key can be inserted and removed in the lockout position as the last two pins are not held in place by the absence of the upper chambers in the last two chambers of the cylinder which do not allow the pins to raise up and allow the passage of a non-modified operating key with intact slopes/notches/steeples...

~~ Evan

[FarmerFreak]

Yes Evan I'm sure Raymond knows very well what a lockout cylinder is and how it works. It could have in some way shape or form help give him the idea to do what he did here.

Now you do have a valid point when pointing out the potential problem with masterkeying this type of cylinder. A schlage rep teaching a class once said that the phenomenon of a master pin staying in the top chamber when the key is turned happens about once every five hundred tries. I think he threw out five hundred as an arbitrary number. But the point is is that it can and probably will happen sooner or later.

So, let's try to be creative and try to circumvent the problem shall we. The first thing that comes to my mind to help prevent this problem (aside from not masterkeying the lock, which would make the entire idea moot), would be to drill the holes for the rekeying position closer to the face of the lock. In such a way that the rekeying pin chambers won't line up with the bottom chambers during regular use. Then you would need to modify the cam/threaded cap on the back of the plug and the back of the housing in such a way that the entire plug can be pulled forward in, and only in that position.

With that idea in mind. It may not be a bad idea to make it so that the cylinder can only be pulled forward in one position and then turned just a little bit to line up the chambers. That way you won't have an issue of the cylinder being pushed back in when the new key isn't yet fully inserted.

All in all, good work Raymond. The only other possible downside is that it may be a little complicated for an end user to do. But that's all that comes to my mind at the moment.

[Raymond]

Hello Mr Farmer freaky,

Once again you have hinted at a new concept in regard to the plug being able to move in or out at a certain point. Kinda of like the face plate springs in in auto ignition cylinders that allow it to be pushed in. This idea deserves thought.

The cylinders I have made in the past have not shown any problem with master wafers sticking or bouncing. But as in all locks, one must be certain the the springs are good and the holes are clean.

I agree that this could be very confusing for the end user if more than 2-3 keys are used at the same time. However, it is a very good solution for simple problems.

If you use a change key that can not come out at the second pin chambers, the change key user will not even be able to detect that they exist.

Anyway, I just thought someone else might benefit from the idea.

Good evening all.

[Evan]

Now you do have a valid point when pointing out the potential problem with masterkeying this type of cylinder. A schlage rep teaching a class once said that the phenomenon of a master pin staying in the top chamber when the key is turned happens about once every five hundred tries. I think he threw out five hundred as an arbitrary number. But the point is is that it can and probably will happen sooner or later.

In practicality you really can not master key cylinders like the one that Raymond has made... They would remain a novelty which would have to not be keyed in with the rest of the building in just about ANY application... These cylinders would have to NOT be a part of the building master key system as you would quickly run out of reserved compatible combination pairs after re-keying one or two of these modified lock cylinders to lock out the user keys that were lost or not returned by the user... After you run out of compatible combinations that have been reserved for use with these cylinders, you would have to scrap the entire master key system in the building and rekey everything to accommodate any more rekeys... Not to mention the fact that your overall master key system size would be impacted by existence of these cylinders in your system...

In a large facility where you would have several of these lock cylinders in use only the shared "High Master Key" would be common to all of them, each individual cylinder would require its own unique "Low Master Key" compatible with its associated user keys which would function as it's reset key... If either the "Key A" or "Key B" of one of these locks was lost or stolen, then both user keys as well as the "Low Master Key" would have to be rekeyed for that cylinder meaning all user keys for that lock would have to be scrapped and reissued to ensure continued security...

In real world use, depending on how many temporary users cycle through, the facility in question would be better served with some kind of credential based centrally controlled on-line access control system with mechanical key override only being available to and used by emergency personnel...

If such a system is not realistic for the application, it could be served by a set of U-Change cylinders and the "boss/supervisor" maintaining a key ring with a copy of every active/available key on it to allow them access to all rooms and allow that individual to rekey the rooms/spaces for the next user when they give out the new temporary key to the person taking over the room/space... This would allow for scrambling (not reusing the same temp key in the same door or lock repeatedly) of the temporary keys compared to the modified cylinder idea which Raymond proposes which only has two user keys available for each lock at any time and would represent a security risk if not deployed on restricted lock cylinders for which duplicate keys can not be obtained by the temporary user of the room/space...

If that solution isn't desirable then SFIC's which are SKD keysets and can be swapped between users of the space and swapped to lock out those with user keys during some lockout period would work better for the building management in the long run... SFIC's would also allow for scrambling as described above...

~~ Evan

[Evan]

The cylinders I have made in the past have not shown any problem with master wafers sticking or bouncing. But as in all locks, one must be certain the the springs are good and the holes are clean.

I agree that this could be very confusing for the end user if more than 2-3 keys are used at the same time. However, it is a very good solution for simple problems.

If you use a change key that can not come out at the second pin chambers, the change key user will not even be able to detect that they exist.

If you created a cylinder of this design in which user keys could not be removed in the second position, you would require more reset/set up keys for the cylinder in order to set them so they can only be used by the specific user key you intend to operate... The cylinders could not longer function in the "whichever user key is used first captures the lock and locks out all other user keys until reset" concept which would defeat the purpose for modifying a lock in this manner as it would now require the boss/supervisor type person to designate which of the user keys should operate by using a unique reset/set up key on the lock prior to the lock being used...

~~ Evan

[Raymond]

Hello Evan,

This cylinder has been in use over twenty years and none of the problems of your negative imagination have occurred.

Although most of your observations are correct as you lumped them together, this cylinder is still quite useful to solve specific problems. I never intended it to be a full part of a masterkey system. I suggested a lot of variations never intending them to be applied at the same time as you have implied.

I think you have seriously over analyzed the idea. So, let's just consider the discussion closed. If you don't want to use it, don't. If anyone else has questions I will deal with them directly. Discussion closed.

[Evan]

Hello Evan,

This cylinder has been in use over twenty years and none of the problems of your negative imagination have occurred.

Although most of your observations are correct as you lumped them together, this cylinder is still quite useful to solve specific problems. I never intended it to be a full part of a masterkey system. I suggested a lot of variations never intending them to be applied at the same time as you have implied.

I think you have seriously over analyzed the idea. So, let's just consider the discussion closed. If you don't want to use it, don't. If anyone else has questions I will deal with them directly. Discussion closed.

It would be nice to know what application you have used this lock in for 20 years and why it has worked out so well for you... If you have not rekeyed that lock in that entire time, it is due to be rekeyed as that is a long time for the locks to operate with the same set of cut keys and pins... They wear out over time... "Keying Systems" should be replaced at least every 15 years to ensure continued security, even in environments where key control is used and you can account for every key being used...

~~ Evan

[femurat]

Hi Raymond,

I find your idea very clever. It reminds me a tubular lock with numbered keys and a set key, that enables only a specific key at a time. I guess it was something related to parking meters.

I appreciate the option of your lock to be re-keyed with just a key. Some stored pins in extra chambers... that you can use and put aside as many times as you want! Something to keep in mind for future projects.

Cheers

[Evan]

Hi Raymond,

I find your idea very clever. It reminds me a tubular lock with numbered keys and a set key, that enables only a specific key at a time. I guess it was something related to parking meters.

I appreciate the option of your lock to be re-keyed with just a key. Some stored pins in extra chambers... that you can use and put aside as many times as you want! Something to keep in mind for future projects.

Cheers

That type of tubular lock is called a GEMATIC and is made by CompX-Fort... You can obtain it as a normal cam style lock or as a cylinder for the "T" handle vending machine type of lock... 8 operating keys and 1 control key...

~~ Evan

[femurat]

Thanks Evan, that's exactly the lock I was referring to. You modify the bittings by rotating the plug with the change key so only a specific operating key works. Since I've never had one of these in my hands I don't know if it's enough to file away the pickup of an operating key to make it work with every combination, given the fact that you can insert it at all the 8 possible angles.

In Raymond's lock this problem doesn't occur.

Cheers