Platform Escapement Refurbishment.

[Kieran McCarthy]

3 years into my Horology journey, I am very pleased with the many new skills that I have acquired. Once I become reasonably proficient in one element I like to push on and explore new skills. I now would like to explore Platform Escapements and would appreciate your help and comments. My friend gave me a carriage clock which appears to be in good shape except for the platform escapement. I cannot determine the origin of the clock and I have taken as many relevant photographs of the clock and escapement that might help me get answers to my questions.
From my untrained eye, there are at least three problems with the escapement. Firstly, it is incredibly dirty. Secondly, the hairspring is missing, and thirdly, the fit between the balance wheel and its arbour is loose, despite non-excessive end shake on the arbour when in its home position. It looks as if the wheel was pressed down when assembled causing it to become loose. Pinions and jewels look good.
Based on the above plus my photographs,
Is the unit repairable, if so, how do I determine the correct hairspring for it, how do I set up the hairspring, and how best do I secure the balance to its arbour.
Any idea of the country of origin or possible age.
any suggestions will be most welcome.
Regards, Kieran

 

[svenedin]

Looks like a French clock, late 19th/early 20th Century. Cylinder escapement as usually used on lower end pieces. Escapement may be Swiss.

 

[gmorse]

Hi Kieran,

Is the unit repairable, if so, how do I determine the correct hairspring for it, how do I set up the hairspring, and how best do I secure the balance to its arbour.

As Stephen has remarked, this is a cylinder escapement, which, being obsolete for many years, could give you a problem in finding someone willing and competent, (and possessed of the necessary spare parts), to restore it. It is repairable, but it won't be a straightforward job even if you're very comfortable with repairs on lever watches.

I believe I can see some damage to the jewel hole in one of your pictures, but it might just be very dirty.

The balance wheel is fitted to the staff, which is a hollow cylinder, by friction in a brass collet riveted into the wheel crossing. The pivots are on plugs which are a friction fit in each end of the cylinder. It's difficult to see from the pictures exactly what state they are in, but almost any work on these will involve a lathe of reasonably high precision, and ideally a Jacot tool to burnish the new pivots if these are required. If a new cylinder is required, they were made in a wide range of sizes and the old assortments sometimes offered on the auction sites are a gamble, because the cylinder dimensions are critical in matching those of the escape wheel.

Finding a balance spring to match the balance will probably be a matter of trial and error using parts from scrap watch movements, these things just aren't sold by the materials houses any more. The balance by itself doesn't have a natural oscillation frequency, but with a balance spring it does, and the process of matching them to produce the correct frequency involves vibrating the balance out of the platform against a known frequency source. You also need to know what that frequency should be, by counting the train.

In summary, these things are firmly in watchmaking territory, so you must decide whether you want to go there, or shell out for someone else to do it, which I have to say, will not be cheap.

Regards,

Graham

 

[svenedin]

The alternative, which is probably frowned upon, is to replace the old escapement with a modern lever escapement. Originally is lost and a new lever escapement is quite expensive. The advantage is the clock is then much more reliable. The cylinder escapement is prone to wear and needs much more frequent servicing.