Radiographing & Moderate Heating of Combination Locks.

Sprockets

Mosler Safe Co, in their US patent, 3111022, covering Tamper-Proof Locks, states that a "rather frequently"used technique for surreptitiously opening a combination lock was to heat same moderately, without even melting or permanently damaging same, when a sufficiently skilled person could open the lock without knowing the combination.

I had never heard of this method, and neither have others in the trade! As this was in the sixties, were thermal auxillary locks introduced in a rush? Was the heat altering clearances, as no permanent damage occurred?

One hears so much about locks proof against Radiographing, but presumably this would only be of use for small, thin walled safes, where back-scattering methods (Even neutron-absorption techniques) might be used. Surely no vault door or other thick steel door was susceptible. Perhaps it was used where a door was left open and unobserved?

Doug MacQueen

I would take issue with the “rather frequently”. Exaggeration in patent filings on the other hand can be said to be “rather frequent”. I too have never heard of the heating technique but have often thought of the possibility of using heat to melt the fairly low melting point diecast widely used since the end of WWII. To accomplish an opening with out damage? Sounds a little fishy.

Vaughan Armstrong

This patent is specifically for the thermal activation aspect of the relock trigger. Underwriters Laboratories Inc. (UL) has required a relock trigger, that will block the bolt’s retraction if the cover is punched off, since 1953 (the first edition of UL 768, Standard for Combination Locks).
At this point (this Mosler patent issued November 1963), the thermal aspect of operation of the lock had not been addressed by UL; it was later.
Sargent and Greenleaf likewise made a thermal - mechanical relock trigger for their locks.

Sprockets

Thanks, Doug, for your speedy “come-back”-interesting comment about the “over-egging” of some patent specifications. I could imagine the melting of die-cast components, but no damage?! Maybe you, with careful monitoring of temperature,could cause a slight change in dimensions, but in a controlled fashion!? The patent almost seems to be insisting that this improvement is imperative, and therefore represents something without which a lock so fitted is valueless. I had never thought of a patent, much flaunted, as a sales pitch before!

Your input, Vaughan, explains why there was so much activity at this stage. It is almost that Mosler hoped to influence the UL in introducing a new requrement, thus forcing competitors to achieve
a new way to gain acceptance, possibly by paying licence fees. The ways of business move in interesting ways!

I am wondering if locks being introduced incorporating protection against radiographing was more a way if encouraging replacement of existing locks, by raising the possibility of such an attack, rather than as a result of actual use of this technique. At the time I believe, in a high level spying case, radiographing had been used, but only for revealing the combination of a lock whose door was left open and unattended during the day, giving access for mounting a film back on the opposite face to the source. It was only used on a thin drawer, I think, as well!!

Thank you, gentlemen, for both your inputs.

Doug MacQueen

I have little doubt that any use of thermal relocking devices was a direct result of oxy-acetylene attacks going back to around WWI. Diebold had patented a vault door thermal link relocking device back in the Twenties. The general idea of relocking protection goes back much further, and is in reaction to a specific form of attack. Once diecast metal replaced bronze and cast iron as the metal used for lock cases and parts, attacking the locks with high heat became more feasible as the melting point of die cast was much lower than than the other metals.

Sprockets

Doug,
Thanks for pointing me in the direction of Diebolds patents, just after WW1.
I found three three thermally tripped auxillary bolts viz-US1600982, 1560432 and 1695136, together with a non-heat tripped relocker for safe-deposit boxes-1452567. These would need the use of oxy-acetylene flames to trip them,(Not the last), so that heat from a large area would trip. Doubtless Mosler had realised that local mild heating of the dial could disable a die-cast component, without releasing a long relocking chain. This explains the emphasis on mild heating, and the statement that such an attack would not lead to any telltale signs, so any insider job might be blamed on this method!
Thanks for your hint! I take it mention of radiographic techniques is not to be voiced!
Martin Cummins.

Vaughan Armstrong

The concept of a lock providing radiographic protection had nothing to do with replacing locks that didn’t provide that protection.

From the early 1950s, at least, our (U.S.) government knew that locks could be X-rayed. There were several instances where radiographic attack was actually used. The earliest General Services Approved security containers had locks with brass wheels. Each container was built with ½″ of lead protecting all six sides of the lock. Development of a lock which by itself provided radiographic protection (by low-density wheels) removed that burden from the container manufacturer, and provided an advantage for that lock in the government marketplace.

The first edition (in 1953) of UL 768, the Standard for combination locks, provided for Group 1 and Group 2 locks. Group 1 locks, among other things, were tested for resistance to expert manipulation. They also were required to incorporate mechanical relock triggers, which would block the bolt if the spindle were punched. Group 2 locks were not tested against manipulation, but had to meet certain requirements of dialing tolerance.

Group 1R locks, meeting requirements of Group 1 and providing radiographic protection, were added to UL 768 in 1961.

Sprockets

Vaughan Armstrong wrote
The concept of a lock providing radiographic protection had nothing to do with replacing locks that didn’t provide that protection.

From the early 1950s, at least, our (U.S.) government knew that locks could be X-rayed. There were several instances where radiographic attack was actually used. The earliest General Services Approved security containers had locks with brass wheels. Each container was built with ½″ of lead protecting all six sides of the lock. Development of a lock which by itself provided radiographic protection (by low-density wheels) removed that burden from the container manufacturer, and provided an advantage for that lock in the government marketplace.

The first edition (in 1953) of UL 768, the Standard for combination locks, provided for Group 1 and Group 2 locks. Group 1 locks, among other things, were tested for resistance to expert manipulation. They also were required to incorporate mechanical relock triggers, which would block the bolt if the spindle were punched. Group 2 locks were not tested against manipulation, but had to meet certain requirements of dialing tolerance.

Group 1R locks, meeting requirements of Group 1 and providing radiographic protection, were added to UL 768 in 1961.

Thanks, Vaughan,

Now all makes sense-the Radiographic Tampering with combination locks, had taken place on thin doors, not massive vault doors, and very likely when open, so back-scattering, with its poorer performance, would not be employed. Good point about the weight of a lead covered Security Container!

Best regards,
Martin Cummins.

[unknown]

Sprockets

Back again, after chewing over for years what is meant by using the “Moderate Heating” involved in “Surrepetitious Opening” of a Combination Security Lock to trigger the Auxillary Lock in The Mosler Safe Co Patent US3111022. No-one had heard of such a method, but I wonder if the source of heat might be created by a drill making an observation hole?

The dial could be removed, the hole drilled, the lock combination ascertained by a borescope,and the evidence of tampering removed by using a new dial. Thus moderate heat means that there had to be no discolouring of the finish, or distortion, so this rules out a blowpipe, which would cause obvious damage. I had wondered about using a burner to sufficiently indirectly destroy the elasticity of an auxillary relocker spring to prevent functioning when the lock case is forced inwards, but this would obviously cause visible and operational damage!

This is the only approach that would seem to fulfill the criteria of the patent-the low melting point alloy is next to the case, which would not be very thick in a security cabinet. Any thoughts?

Thanks. Martin.

Doug MacQueen

No generally speaking drilling the Mosler 302-402 lock does not release the internal RL. At least that is true where I drill the lock. I suppose drilling close to the RL with dull drills may create sufficient heat. But that is not something I will test out.

Sprockets

Thanks, Doug, for your speedy reply. I was relieved that you thought it might just be possible, but perhaps a 1960’s tipped drill might not match your present drill in cutting ability! Thank goodness you are not going to try tweaking a RL, as you would have to obtain an old drill!

Thanks,Martin.