Cotehele Clock

Cotehele is an ancient house on the banks of the river Tamar in east Cornwall. Now owned by the National Trust it is home to a remarkable survivor of a clock.

Located in the chapel in an alcove is some ancient machinery which is the oldest unaltered turret clock in UK which is still in its original position. Furthermore it the oldest clock with its original verge and foliot escapement in the world. It can be dated to a few years around 1500.

It perhaps at first glance does not look like a clock as it has no dial and no hands for indicating time but it does strike the hours on a bell in the belfry above as it has done so for 500 years.

But it is rather spectacular, from its rather crude wrought iron frame and gears to its wonderful mechanical motions, particularly when it strikes.

The original clock in uts alcove where it has stood for 500 years

I thought it would be interesting and instructive to make a replica of the clock to study it further.As is my wont it is largely made out of wood with metal employed where only strictly necessary. It is half scale.

The parts are laser cut from 3mm plywood.

The rock weight powering the going train may look odd but this is how it is in the original, albeit there it weighs  some 40 Kg

The half scale replica

Differences from the original are that the bell is mounted on the clock rather than remotely in a belfry and both weights  should be on the same side and mounted on a wall adjacent to the clock.

The foliot in the real clock makes a full swing in just over 12 seconds but due to scale effects I have not been able to get more than 9 seconds and since I have employed the same gearing as in the prototype this clock does not keep time.

It does however work as a valuable demonstration of adjusting the rate of a foliot as by moving the weights inwards or outwards the period can be changed from 2 seconds to 9seconds. Heavier weights may achieve the right frequency but whether the verge suspension can stand it is another matter. The foliot could also be lengthened but then it would not be in scale.