Sometimes it’s easy to not see the wood because of all the trees..
Seeing the shape of the Herring change key that Yankee has kindly posted it looks like it resembles a ‘cut away’ safe key which could be replicated very easy by any good locksmith or safe tech without needing any real fabrication. You would need an original Herring change key to copy from though, as like Yankee says the dimensions and tolerances are critical.
Cant see any reason why it can’t be cut simply like it was a pin lever safe key:
1- select a very long pin key blank which matches the pin gauge of the Herring key, but also critically the ‘bit’ must be of equal thickness and adequate overall length along the end of the pin.
2- cut the surplus height of the unwanted part of the bit away, and then set both onto the cutting machine using the original Herring set in the machine to copy from.
3- Cut the key exactly as the Herring pattern
4- turn the taper on the end of the pin, or file by hand if no lathe available.
From what I see of the shape, this simple technique should cut a copy like it was any other standard lever safe key, can’t see any reason for any problems as long as the blank selected has the correct dimensions to start with. It might of course need a lot of hand finishing afterwards, chamfering etc, but it would take a fraction of the time compared to going the brazed bits into bar fabrication route…
Beautiful old safe BTW OP, seeing those hinges reminds me of the classic ‘rolling pins’ seen on the old British Hobb’s Harts. Hope you get it sorted.
