Hatton Gardens

[Doug MacQueen]

I see Ratner didn't start until 1889. He could have been using Hadfield manganese steel. It work hardens big time. That might explain the difficulty.

[Huw Eastwood]

Yes it was without doubt a work hardening steel on that one.Talking of brittle hard plates, I lost count of how many we'd see where they'd fractured with time alone, usually across a corner from where they were riveted to the door.

On the subject of the drills, I would think the twist drills were more widely used in general engineering for mild steel work on drilling machines, lathes and mills etc.

Since it looks like these guys were modifying or making their own for dealing with the hard steels, my bet is they'd go with the flatter spade tips. If I remember right the old Frhei drills had pretty flattened ends on them, although I have to admit even the old ones Ive seen were fitted on fluted twist style shanks.

[Doug MacQueen]

I should have said manganese steel can work harden if drilled incorrectly. It's true breaking the plates was a technique, but the question is how were they drilling 4" holes through them. The pictures clearly show the stack of the cutout discs from the safe. I will post a picture soon as get more $$$&#% ink for my printer.

[Huw Eastwood]

I thought church safes had to be "fire resisting" safes if they were being used to store records of marriages etc. I live and learn.

They might have had a modern Chubb 2 hour rated fire safe around the corner for all that stuff!! It's that long ago I haven't a clue but many Churches often had a couple as the silver, money from collections and other valuables often ended up in them as well.

[Chubby]

When did tungsten carbide become available?

[Huw Eastwood]

When did tungsten carbide become available?

I mentioned that back in post number 58. Osram apparently developed it originally, and then Krupp's took it on and developed it further, think it was mid to late 20s when the first tooling came onto the scene.

[safeman]

I see Ratner didn't start until 1889. He could have been using Hadfield manganese steel. It work hardens big time. That might explain the difficulty.

At the time of the wrangle with Chatwood in 1893, Ratcliff & Horner were using Congreaves Patent Safe Steel plate. Chatwood drilled the 3 test plate which had been claimed undrillable using a hand ratchet drill. Ratcliff then accused Chatwood of having softened the plates before drilling and commenced an action in the High Court for slander which prompted Chatwood to purchase a new safe bearing the claim that "this door is made of hardened Congreave Patent compo safe steel, absolutely undrillable and unbreakable" which Chatwood drilled by hand "just as a burglar would and without scratching the paint". Case withdrawn.

[safeman]

I should have said manganese steel can work harden if drilled incorrectly. It's true breaking the plates was a technique, but the question is how were they drilling 4" holes through them. The pictures clearly show the stack of the cutout discs from the safe. I will post a picture soon as get more $$$&#% ink for my printer.

I have gathered together on or two items which are relevant to this discussion.

The first is on the subject of case-hardening as described by Geo.Price in his Treatise on Gunpowder-Proof Locks & Drill-Proof Safes 1860.

Secondly there are the composite drill-resisting steels used for doors, bodies, lock mounts, and strongrooms.


The earliest was by John Tann. Ratner and Milner also
used a 5 layer sandwich of high and low carbon steels rolled together in the furnace. Having the softer layer on the
outside enabled the likes of Ratner to affix their escutcheons and nameplates on the surface.

It is particularly interesting to see Chatwood's reference to the use of circular cutters to create a manhole in a strongroom wall.

[Doug MacQueen]

This just keeps getting better. Thank you Safeman, Max and Chubby for keeping this discussion alive and interesting. Too bad its buried in Hatton Gardens. Anyway here are twist drills having been used in a 1875 US burglary. 5 ply and even 7 ply rolled steel plates were also commonly used here during that era, interspersed between the mild steel plates. As far as I know these were always made of hi and low carbon steel layers hot rolled together. The fact that Chatwood drilled one in "93" is something. On the case hardening, yes it can be carried deeper. It's most recognized advantage is that it presents a hard surface while remaining tough due to the malleability of the mild steel core. Does Price say how deep he took it? On the Mosler doors I drilled it was definitely more than tissue thin, but not so deep I couldn't quickly grind down past it and start drilling. I am no metallurgist, but I think thoroughly case hardening a mild steel plate would then make it brittle just like the overly hardened hi carb plate they used. Were these hi carb plates tempered at all?

[Huw Eastwood]

Yes its definitely getting better, the literature safeman's posted is going to take a while to chew over, and I'm sure it'll add a lot of further scope for thought, but as I'm a hands-on and direct experience sort of bloke, I'll stick my neck on the block and add this for now: when it's down to steels, alloys, hardening, tempering, manufacturers claims etc, you can pretty much make what you want of it.

Before I ventured into my own tungsten carbide and cubic boron nitride bits I'd dabbled with good old fashioned silver steel- lots of it!
For me its still the most mis-represented and underestimated basic 'tool' steel there is. All you hear is, 'it'll be so hard it shatters' or, 'it won't be hard enough to cut through that'.

well, having made many different types of cutters for hand-tool and machine tool use, and all without any problems with regards to hardness or brittleness, the rumours did eventually get me doubtful on the brittleness of tapered safe plugs I'd been making in batches for years. This led to a simple but extreme experiment which involved a 25 kilo block of steel on the concrete workshop floor, a very large sledgehammer, and a hardened safe plug I'd made to maximum hardness without tempering. The outcome was a lot of shouting, expletives, people diving in different directions, and a broken double glazed window. The Plug itself showed a few 'flats' from impacts but apart from that, had retained the fine tool marks from initial turning, it's polished finish, and it remained intact.

Before that simple experiment I'd spent a lot of time, which with hindsight was pretty much wasted, experimenting with different levels of tempering with the sole belief that it needed it and it had to have it. That was just plain old Stubb's carbon silver steel. I haven't a clue if it's available in the USA, or what silver steel is called your side of the pond if you can get it, but it's not an exotic steel by any means. In fact I seem to remember explaining the whole silver steel thing before to Doug in one of my model vault posts.

Anyway i have to admit these in-depth posts are proving time consuming on this new iPad, and I have to mention the kindness and help of our member mercury, who's enabled me to enlargen any posted info and pictures without them jumping across the screen to oblivion. Thanks Mercury, I can at last have a proper closeup look at the recent pictures and scans!