Gents C7 electric master clock

[Robert Atkinson 2Participant @robertatkinson2]

I’m a bit of a “time-nut” in the electronic equipment sense. I have a few GPS disciplined clocks / frequency standards. And some atomic (Rubidium) references. I can measure time intervals down to a few 10’s of picoseconds.
I’ve always fancied a electromechanical Master Clock system. When a member of an electronics forum offered a Gents master clock and two slaves free for collection I was interested. Unfortunately collection was a 3 hour drive away. However, it was only a short distance from a family member who was coming to visit me about a week later. So I asked if they would pick up a couple clocks for me. They said yes. Seems I forgot to tell them one was five foot long! In my defence I hadn’t actually asked what the clocks were. Turns out to be a later mode C7 with integral slave and a couple mid-sized slaves.
First issue was while the pendulum had been removed to prevent damage, the case was locked and there was no key. Someone had slightly damaged the wood trying to force it. Thus a bit of locksmithing was in order. Lock appeared to be a high quality cabinet lock with claw keeper and pipe (tubular shaft) key. Having made a few measurements of the slot I visited the local Timpsons to buy a blank. They actually gave me a blank free of charge and said come back and pay for it if you can make it work. The bit on the blank was much too large So reduced that on the mill so it would go in and turn. Then blued it up, turned in the lock and then hand filed according to the witness marks. One more blue and file and it unlocked. Not pretty but it works.

[Michael GilliganParticipant @michaelgilligan61133]

A great start, Robert !

MichaelG.

[John HaineParticipant @johnhaine32865]

Have fun with it, and enjoy the clicking!

[peak4Participant @peak4]

A few links related to similar stuff which you may already know about
Light Straw, note the navigation menu top right after entering, which leads to lots of documentation
https://www.lightstraw.uk/gpo/clocksystems/

Some stuff on GPO Clocks
https://britishtelephones.com/menucloc.htm

And there’s an io group.
https://groups.io/g/electric-clocks/topic/a_strange_gent_s_gpo_type_36/95815827

I have a couple of ex GPO pendulum masters, but without integrated clocks, though I’ve not got either set up yet since we moved house.

Bill

[Robert Atkinson 2Participant @robertatkinson2]

Already joined the I.O. group. Further investigation of the parts shows the pendulum suspension spring is broken. Fortunately all the bits are there and the dimensions of the spring strip are available. I now need to get a bit of 15 thou thick, or more likely 0.4mm spring steel. As usual I’ll likely have to buy far more material than I need.

Robert.

[peak4Participant @peak4]

I’m not sure that we had any/many C7 models, but there’s a manual here, second post down.
https://mb.nawcc.org/threads/gents-c7-master-clock-docs-and-info.199686/

Bill

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