In another thread I mentioned a Chatwood Duplex which was classed as a sub standard plate safe because it was just a 1/4 plate shell although the front was of standard duplex quality. This was because it had originally been designed as a night safe and was concreted into a wall. It was not designed to take cash, but that is another story.

COD got their hands on it and under my instruction altered it more than a little. They riveted progressive layers of various metals inside the skin including IT100 armour plate, copper and stainless. They then fabricated a box inside and poured high aggregate concrete, reinforced with expanded metal and vibrated that until it formed a monolith between the skins. This was all poured in through the base, I think.

As a night safe the casting at the bottom of the frame was deeper than the top and sides by a couple of inches but the monlith was uniform thickness all round. That left an area the size of the whole inside and a couple of inches deep in the base. When making the body they had incorporated base fixing holes. These were covered by a sliding panel at the level of the base of the door. I had to remove 4 allen bolts which fixed it in place and just slide it out like the lid of a pencil case.

I think most readers will be aware of the basic weakness of a duplex. They altered things to remove that weakness but I am not about to describe the weakness on a public forum.

They also extended the boltwork and added a very neat live AED immediately above the lock. Of course we kept the standard dead AED, with the hole in the boltwork offset so as to frustrate a preloaded handle attackThe most amazing thing was that they machined 2 keys out of solid steel. These were double bitted and that dual control lock is to some fairly tight tolerances! I don't know how long that all took but the keys were superb!

In case anybody reading this has never seen the dual control lock, I shall explain. It looks on the outside just like any keyway for a Chatwood double bitted key. There is only 1 keyway. To open, key A is inserted and tuned through 180 degrees and removed. Then key B is inserted through 90 degrees at which point it stops. To lock the unit key B is turned back 90 degrees and removed. The safe is then completely locked and you need bot A and B to reopen it. How neat is that?