Pendulum

[Willow]

Got this French clock the other day not ready to work on it yet, need a pendulum for it also double ended key problem is i don't no the length of the leader or the weight of the bob.  Are the numbers at the bottom right the length of the leader, hope you can understand all that, can anybody advise me please.

[nickelsilver]

I don't know about the numbers, but you can calculate the length with this calculator

 

https://theindex.nawcc.org/CalcPendulumLength.php

 

Weight is far less of an issue than length (effective length is what gives its frequency); what you'll find that's in the ballpark for length will almost certainly be OK for weight.

[Willow]

Thanks nickelsilver is that the only way didn't really want to strip it down yet, but i there is no other option i wii have to do that.

[clockboy]

On the back plate of most french clocks there is a series of numbers of which in part give the length of the pendulum required. See link below:

 

https://www.m-p.co.uk/formulae/frpend.htm

[Willow]

thanks clockboy there are numbers on the back as photo but which one are they, any ideas on the key or bob. 

 

[clockboy]

I can’t quite make it out from your pic but the one that is I think 4.11. If so your pendulum should be 133mm. This taken from the top of the suspension spring to the centre of the Bob.

 

[Willow]

thanks clockboy yes the number on the right is  4 11 any ideas about weight or bob

[clockboy]

Sorry I do not know that 

[oldhippy]

Looks like 758 this is the movement number.

4 11 is the length in French inches

The date is 1888

2.5 oz is the most popular weight. So I would go for that.  

[Willow]

Thanks for that oldhippy can you still get a double ended key for this clock given the age. Also it has a regular mantle clock suspension spring or do they have a much longing spring.

[oldhippy]

Yes you can get keys. This is the type key you need. The suspension springs also come in different sizes. If you have the old one measure the length.   Could you post a photo of where the s/s is fitted then I can be more precise on which one to buy. Any good suppler with stock both of what you need.  

[Willow]

Here is the photo it measures 30.1 mm and has two plastic ends instead of brass by the look of it is that normal on a clock from 1888

[oldhippy]

Good you have the old one or through as it has plastic ends its not that old. Just order a replacement of the same length, my preference is for brass ends as the original would be brass but its up to you.  

[Willow]

I will go with brass the plastic look cheap thanks oldhippy