HHM Single Nose Lever/Safety Deposit Lock

[Jacob Morgan]

Found this at a junk store last weekend for $3. Probably the price was low because the key would not open the lock. Bought it anyway. Probably ho-hum stuff for the professional locksmiths here who work on these things on a regular basis, but it is an interesting design to someone like me.



The key has HHM Safe Co (Herring Hall Marvin?) stamped on it. The lock itself has no markings at all, none. I was thinking that it was supposed to work with a single key and something was broken, but it seems that it used both a guard key and a renter key but with only one keyway. A clever idea, but it may have freaked out bank customers (the person with the guard key may have had to explain a lot that no, their key alone did not work)? Looking at the picture below, the tumbler closest to the front would not move when the key was turned.



Lifted and moved to the left that first tumbler with a large hook pick and it stayed put. Then the key worked. I don't think that would be easy to do (unless one made a hook that had a sharp 90 degree angle in it) if that window was not there.



Taking it apart, there was a copper sheet covering the innards.



Removing that, the first tumbler is visible. The pivot hole is elongated and it seems that a special guard key would be used to raise it up and then as the key was turned back to the left that tumbler would stay in the unlocked position. Then the renter key would work, and then when the renter key was removed it would take that first tumbler back out of position.



I need to get some sheet brass or see if Ilco makes something close and try to make a guard key (and see if I can impression the renter key), but in the mean time a small bit of hard rubber was placed into the elongated hole of the first tumbler (the pick is pointing to it) to eliminate the need for a guard key.

[Robotnik]

I'll preface this by saying that I've never worked on that specific lock, but...from what I'm seeing, there's no guard key. Should be able to impression a single key to operate that.

I've purchased bank locks from large lots before, and one thing I'll say is that sellers often pair the wrong keys with locks. That may be the situation here.

[Jacob Morgan]

I'll preface this by saying that I've never worked on that specific lock, but...from what I'm seeing, there's no guard key. Should be able to impression a single key to operate that.

I've purchased bank locks from large lots before, and one thing I'll say is that sellers often pair the wrong keys with locks. That may be the situation here.

When that first tumbler is set, the key works fine. That first tumbler is shaped completely different from all the others--one can pick it without tension and that tumbler stays set when the pick is removed. Trying to reverse engineer the design it seemed logical that it would take a special key to set the first tumbler before the renter key was used.

Looked into it some more and it looks like it would take a "prep" key. An example of a currently made safety deposit lock of that nature is here: http://www.bullseyesdlocks.com/safe-deposit-locks/b2401-group/ The product description is: "The B2401 requires insertion and rotation of the Prep Guard key prior to the insertion and rotation of the renter or customer’s key in order to retract locking bolt. It is intended primarily for service use in Canada’s major financial institutions. A single key operated version is available upon request." There are only a total of 4 possible prep keys--not exactly high security, eh.

[Robotnik]

I'll preface this by saying that I've never worked on that specific lock, but...from what I'm seeing, there's no guard key. Should be able to impression a single key to operate that.

I've purchased bank locks from large lots before, and one thing I'll say is that sellers often pair the wrong keys with locks. That may be the situation here.

When that first tumbler is set, the key works fine. That first tumbler is shaped completely different from all the others--one can pick it without tension and that tumbler stays set when the pick is removed. Trying to reverse engineer the design it seemed logical that it would take a special key to set the first tumbler before the renter key was used.

Looked into it some more and it looks like it would take a "prep" key. An example of a currently made safety deposit lock of that nature is here: http://www.bullseyesdlocks.com/safe-deposit-locks/b2401-group/ The product description is: "The B2401 requires insertion and rotation of the Prep Guard key prior to the insertion and rotation of the renter or customer’s key in order to retract locking bolt. It is intended primarily for service use in Canada’s major financial institutions. A single key operated version is available upon request." There are only a total of 4 possible prep keys--not exactly high security, eh.

Ah, makes sense. Was thinking of a guard key in the traditional sense, and wasn't seeing that being feasible based on the mechanics of the lock. Basically, it's prep key used to set the first lever, then operating key (which you have) used to operate lock?

[Jacob Morgan]

Pretty sure it is a prep key then a normal renter's key.

Here are some more photos, the lower tumbler is the first one (for the prep key), the top one is just like all the others.


Here it is with everything locked.


Here it is with the prep key tumbler unlocked.

[Jacob Morgan]

Finally found a flat key that was sort of close to the renter key from which to try to make a prep key. It was not the correct key, but the best I could find. Clamped the blank to the renter key and took a scribe and made some lines, then extended them and cut out the excess with a flat balde on my Foley Belsaw key cutter. I left metal where the first tumbler was, thinking I could file to fit later. I should have probably left some metal near the tip to make a shoulder so the key would not go in too far, but cutting it as shown did not hurt anything.



The prep key actually worked the first time without any fitting. Dumb luck. It would probably work a little better if it was wider where it engages the first tumbler (again, not the right key blank), but it does position the first tumbler out of the way enough to work. The picture below shows the renter key on top of the prep key.



To recap: the renter key can not unlock the lock after it is locked. The prep key is inserted and turned to almost 90 degrees clockwise, then turned back almost 90 degrees counter-clockwise and removed. Then the renter key is inserted and turned clockwise and the bolt retracts. Turn it the other way and it is locked again (and will not open without the prep key).

Now I need to re-read Gordon's tutorial on impressioning lever locks and give that a try now that the prep-key is out of the way.

[peterwn]

[quote="Jacob Morgan"]Pretty sure it is a prep key then a normal renter's key.

I saw a lock of this sort years ago. The custodian had another key on his ring which looked like an inverse of the prep key (zero cuts except for the prep lever cut which was deep enough not to touch the prep lever). I presumed this was an un-prep key in case the custodian accidentally prepped the wrong box.

The customer also had to leave the key in the lock when accessing the removable tray in a privacy cubicle, otherwise he had to get the custodian to prep the lock again to re-lock the box.

Presumably the purpose of a guard or prep key is to prevent a person authorised to enter the vault to access his own box accessing some one else's box. This would be of concern since a log is kept of what boxes are accessed, and in the absence of a guard or prep key there is risk of an unlogged box access. A determined person up to no good could however fairly readily make a false prep key, especially as most boxes would use flat rather than 'paracentric' (in the detention key sense) keys.