I talk to many locksmiths who are just starting out.  Most of these folks ask automotive questions, but fairly often, I get asked about safe deposit locks.  I guess it’s because I produced a three-volume set of DVDs on safe deposit lock servicing a few years ago.  Here is a very basic introduction to the subject of safe deposit lock servicing, intended for those who are locksmiths, but have no experience at all in working on safe deposit locks.

The vast majority of safe deposit lock work is done today by dedicated bank equipment service companies.  For that reason, many independent locksmiths believe that they simply can’t get that kind of work. 

The problem with bank equipment service companies is that they try to schedule their work weeks in advance, and a lot of safe deposit work has to be done on short notice.  If a customer comes into the bank to access their safe deposit box and his key won’t work, he won’t want to wait a week or two for the bank to schedule a box opening.  Failure of a safe deposit lock is very rare, but there are lots of other situations involving safe deposit locks that have to be handled quickly, such as a renter who needs immediate access to their box, but has lost the key, the death of the renter, or a court-ordered box opening, etc.  If you are willing and able to respond quickly, there are many opportunities for the average locksmith to do safe deposit work.

Of course there are other advantages, like the fact that safe deposit locks tend to be in well-lit, air-conditioned areas.  Banks tend to be pleasant places to work, and they have lots of locks that the bank service people don’t normally service.  Those locks also get used every day and consequently need regular attention.  These range from the locks on the front doors, individual office locks, and lots of locks on individual desks and drawers.  Once you have established yourself with a bank, it’s only natural that they will call you when one of these “minor” locks needs service.

Most modern safe deposit locks are actually two separate locks inside one housing that work together to control a single locking bolt.  The whole idea is to have a lock that requires two different keys before it can be unlocked.  Traditionally, a single key is used to control one side of all of the safe deposit locks in a bank.  This key is maintained by the “vault custodian,” and is called the “Guard Key.”  The guard key is always inserted into the lock plug that is the closest to the hinge on modern locks.  Once the guard key has been turned and left in the turned position, then the key that the renter of the box controls is inserted into the other plug and turned to unlock the box.  Naturally enough, the key that the renter controls is normally referred to as the “Renter’s Key.”  Only when both keys are inserted and turned can the box be opened.

Since there are two different locks in one unit, there are twice as many elements to fail, but because most safe deposit locks use old-fashioned lever tumblers, these locks rarely fail. 

Most safe deposit lock servicing boils down to opening and repairing a box when a key is not available.  While there are some picks available for some locks, there are many banks that will not permit you to use them, simply for public relations reasons.  Many banks want their customers to believe that there is absolutely no way to open their box without destroying the lock.

While there have been many different companies making safe deposit locks through the years, the most common ones are from one of four major manufacturers: Diebold, LeFebure, Mosler and Sargent & Greenleaf. For a more complete list, see the Locksmith Ledger Web Site Buyers Guide.

I’m going to limit my discussion to these four manufacturers who control most of the U.S. market.  Mosler has been out of business since 2001, but so many of their locks are in use today that I had to include them in this article.  After Mosler declared bankruptcy in 2001, Diebold bought much of the company and still supports many of the former Mosler products.  In addition, replacement locks for Mosler safe deposit boxes are now available from third-party suppliers.

Safe deposit locks generally fall into two broad categories: fixed-lever locks and resettable locks.  Fixed lever locks have to be disassembled in order to change the combination.  This type of lock rarely fails, unless someone damages them, either by trying to force the wrong key to work the lock, or by inserting something other than a key into the lock.

As the name implies, the resettable locks can be reset to accept different keys.  Some resettable locks only allow you to reset the renter’s side of the lock and some allow you to reset both sides of the lock.  The older a resettable lock is, the more trouble it’s going to give you.  Some of the early Diebold and S&G resettable locks used delicate mechanisms that will often slip, causing the lock to fail.  The older these locks get, the more easily they can lose their settings. 

Modern resettable locks are for the most part ruggedly built and are easy to service.  They tend to use heavier components that are less likely to slip.

Almost all safe deposit locks use lever tumblers for both the guard and the renter’s keys.  Most modern locks use seven levers on the renter’s side, but some older locks may have as few as five.  In a new installation, there will generally be the same number of levers on the guard side as well.  But in many cases, you will see only a few working levers on the guard side, with spacers between the working levers.  This is what is known among safe deposit technicians as “Match Work.”  Match Work is done when you have to match a new lock to an existing guard key, which may have originally been made for a completely different kind of lock.  You will see this in older banks where additional “nests” of safe deposit locks have been added after the original construction.

A good example of a simple fixed-lever lock is the Sargent & Greenleaf 4400 series of locks.  These simple locks may be the most common safe deposit locks out there.  Like most safe deposit locks, they are available in both a right-hand and a left-hand version.  Most of the safe deposit locks that you will work on will be right-hand locks.  Generally, the left-hand locks are only used on the last row of boxes in a nest so that the door will swing away from the wall if the nest is mounted in the corner of the vault.  The lock shown in these photos is a right-hand lock.

Note: Review the terminology in the sidebar at the end of this article to help understand the operation of the lock. 

When the guard key is inserted and turned, it aligns all of the gates in the guard lever stack with the fence on the guard side of the lock bolt.  Then, when the renter’s key is inserted, it aligns all of the gates in the lever stack on the renter’s side of the lock with the fence on the renter’s side of the lock bolt.  As the key is turned further, the foot on the renter’s post contacts the lock bolt and pulls it back to unlock the box.  If any gate on either side of the lock is not properly aligned, the bolt cannot be withdrawn because one or both of the fences will be stopped by the lever that is not properly aligned. 

In almost every case, you will have a working guard key for any safe deposit lock you will need to open.  Invariably it is the renter’s key that either gets lost or is unavailable. 

You could drill a hole in the safe deposit box door above the gates and then manually pick each lever, but that is something that you want to avoid if at all possible.  In fact, most banks won’t let you drill a door under any circumstances.  The only time I have ever used that procedure was on a bank with antique locks that simply could not be replaced.  Even then, I had to be extremely careful to drill the smallest hole possible and to make my repairs to the door as invisible as possible.

Box opening procedures generally fall into two categories: pull the door or pull the renter’s nose.  There are tools on the market to take care of both situations, but my favorite is the LKM1010KIT from Lockmasters, Inc.  This kit contains a door puller and a nose puller along with all of the accessories needed to handle just about any job, plus volume three of my safe deposit lock servicing DVDs, which covers box opening.

In the photo of the S&G 4440 lock with the horn-plate and noses removed, you will see that without the renter's post in place, the renter’s levers have all dropped down to the point where the fence could slide over them.  This will happen on virtually any of the fixed lever locks if you are able to pull the renter’s nose and post out of the lock.  A nose puller allows you to do just that.  There are lots of ways to attach the nose puller to the nose, ranging from a hardened sheet-metal screw to a hardened machine screw, which requires you to drill and tap the nose, to specialty blades for some Mosler locks that just snap in behind the nose.

Regardless of how you get the nose out, once you have it out, you will still have to insert and turn the guard key and then find a way to move the bolt now that the renter’s post and foot are gone.  My favorite tool for this is a Shrum tool.  All you have to do is insert the tool into the lock where the foot used to be and flip the bolt back.  Sometimes you may have to vibrate the door or use a screwdriver or ice pick to pull the levers down far enough for the fence to pass over them, but this is not usually too difficult.

If you ever have a case where there is no guard key, you can also pull the nose on the guard side of the lock in the same manner and the levers on that side will also drop low enough to pass under the fence. 

The few times that I have had to do this was on a safe deposit lock outside of a bank.  You will find safe deposit locks in use on some inner compartments in safes and very often on rotary-hopper drop-safes that are used by some trucking and delivery companies.  

Door pulling involves forcing the door open without retracting the lock bolt.  This naturally ruins the lock, but in many cases, this is the best option.  As a general rule, the banks don’t care about repairing a lock when the box has to be opened because the renter lost the key.  They simply pass the cost of the opening and the replacement lock along to the customer who lost the key.  In fact, banks usually stock locks for just this purpose.

The process of pulling a door starts with pulling the renter’s nose and inserting a hook-like “Puller Bolt” into the opening in the lock.   Once the puller-bolt in securely hooked onto the inner surface of the door, a bracket is mounted across the frames of two or more boxes so that the puller bolt can be tightened, which will force the door out, breaking the lock in the process.

It is extremely important to place the supports for the puller bracket securely on the frame members of the nest.  If the support slips, or you accidentally place the support against another box door, you can easily force the wrong door inward rather than pulling the door that you wanted to open outward.  Opening the wrong safe deposit box or damaging another safe deposit box is about the worst thing you can do while working inside a bank vault.  This will cause a huge headache and public relations problem for the bank, and it will probably be the last work you ever do for that bank.

On a related note, being told by the vault custodian to open the wrong box by mistake is always a danger.  This is why I always have the bank custodian write down the number of the box that I am to open and verify it verbally before I ever touch the door with a tool.  If you have written proof that you were told to open the wrong box, it’s much harder to blame you for the vault custodian’s error.

While older resettable locks can be a royal pain to work on, the newer locks are generally well-made and easy to service.  The problems come in when unskilled people try to reset these locks, or when someone loses the key and the box has to opened. 

Our current economic problems are causing everyone to cut expenses wherever they can and banks are no exception.  More and more banks are resetting their own safe deposit locks when a renter relinquishes a box.  Unfortunately, most vault custodians don’t really understand the mechanics of what they are doing, and they make mistakes.  And when they make a mistake, it becomes our job to correct the problem.

Resettable locks fall into two categories: locks that have resettable levers, and locks that have resettable fences.  Let’s take a brief look at an example of each type of lock.

LeFebure 7700 Series Resettable Lever Lock: The LeFebure 7700 series is a very cost-effective lock for banks and locksmiths.  The lock is normally reliable, but if you are not careful when you reset it, you can easily run into trouble.  Some very early 7700 series locks used nylon parts, but the high failure rate soon forced LeFebure to switch to diecast metal.

In addition to resettable levers, this lock features levers that face in opposite directions.  The levers on the guard side face the fence on the guard side and the levers on the renter’s side face the fence on the renter’s side.  Once again, the lock bolt can only be withdrawn when all of the gates are properly aligned with both of the fences.  This lock is also symmetrical, so it is non-handed.  The same lock can be used on a right-hand door or a left-door just by flipping it over.

The settings of the levers are controlled by a toothed shaft that runs through the center of the lock.  The shaft can be turned with the change tool from either the top or the bottom of the lock, so it is not necessary to take the lock off the door to reset it.  To reset the lock, begin with the lock in the unlocked position, with both keys in place and turned.  Then turn the shaft with a change tool to release the levers.  Once the levers are released, the keys can be turned to the second key-pull position and removed.  The new keys are inserted and turned, and then the shaft is turned back to the locked position with the change tool, which completes the resetting operation.

The trick to changing these locks is to wiggle the change tool back and forth as you lock the levers back in place.  If you simply turn the tool to the locked position and stop, one or more levers may not be securely locked into place.  If that happens, the lock will work a few times until the levers slip one tooth over and lock in.  This will result in a lock that is either very hard to work, or will not work at all.  In addition, the cheaply made change tool that is supplied with the locks is made of diecast metal and it is easy to break off one of the tips.  After-market change tools such as the LKM7700 or the LKM3111 are more durable and easier to use.

When it comes to opening a box that is equipped with a LeFebure 7700 series lock, you have little choice other than pulling the door.  As you can see in the photo, pulling the nose on the renter’s side will not allow the levers to drop far enough for the fence to pass.  Even after pulling the nose on the renter’s side, you will not have enough room to insert the puller bolt.  The fix for that is a little bit of brute force with a large screwdriver, and sometimes a hammer, to deform the levers far enough to get the puller bolt inserted and seated.  This is not really a problem since pulling the door is going to totally destroy the lock anyway; it just makes the job a little harder.

Diebold 175-70 Resettable Fence Lock:  This lock is handed like the S&G 4400 series and the lock uses resettable fences on both sides of the lock.  When resetting the lock, you can choose to reset one or both keys since there are two separate resetting mechanisms, one for each key. Normally, you will not be changing the guard side of the lock, unless you are installing a brand new lock.

The resettable fences consist of a group of seven “L” shaped fence components sandwiched together.  Each fence component is free to float up and down between two pins on the bolt.  The change mechanism consists of a plate on top of the fence components that is held in place by the change screw.  When the change screw is tightened, the plate is clamped down onto the fence components locking them into place.  When the change screw is loosened, the fence components are free to move.

The process of resetting the lock begins with both keys inserted and the lock turned to the unlocked position.  The change tool, essentially a hollow Allan wrench, is inserted into the opening on the renter’s side of the lock and used to loosen the change screw.  When the change screw has been loosened enough, the lock bolt will be able to retract further than normal, allowing the renter’s key to turn to the second key-pull position.  The old renter’s key is then removed and the new one inserted and turned.  The bolt will not be able to go all of the way to the locked position until the change screw has been re-tightened.  The change tool is then used again to tighten the change screw and the job is complete.  It is important to tighten the change screw enough that it does not slip, but not so tight that you strip out the threads in the plate.  That is why the factory change tool (P/N LKM17570CHG) has a clutch to prevent overtightening.  If you are using a combination change tool like the LKM3111, which is designed for use on both Diebold and LeFebure locks, make sure that you don’t over-tighten the change screw.

When you need to open a box equipped with a Diebold 175-70 lock, you have a choice of either picking the lock or pulling the door and destroying the lock.  This is one of the few safe deposit locks that can be picked easily, as long as you have the proper tool. 

The problem is getting the bank to let you pick the lock.  As mentioned earlier, many banks do not want their customers to think that their safe deposit lock can be opened without destroying the lock.  That having been said, not even banks want to throw money away in this economy, so if you want to use the LKM2098 tool, you should discuss it with the bank custodian privately before you begin.