Pendulum for a Grandfather clock

Posted: Thu Aug 19, 2010 11:11 pm     Post subject: Pendulum for a Grandfather clock

Hi everybody.

I have just inherited my first mechanical clock, an old longcase made by my great great grandfather, George Tew.

In my lifetime, it has not worked, and my father never showed interest in gettign it working.
Now that I have it, I would like to see it work.

I have pulled down the movement, and cleaned it all up and reassembled it. All seems well, and I see no reason for it not to work.
However, there is no pendulum shaft or suspension spring. I'm not sure when this was lost, perhaps that was the reason it never worked.

I have the Pendulum bob & slide, but no shaft or spring.

So my question is, what is involved in replacing the shaft and spring?

I beleive it to be an 8 day longcase movement.
From pics i have seen, the rod could just be a piece of steel rod, threaded each end. What length should it be, or how do I calculate/guesstimate the length?

As for the spring, I see them for sale via the web, but there does seem to be a critical length here.
Any suggestions on how to get the right spring?

Photo's included to show the movement etc.

Any help greatly apprecaited.
Cheers
Dave

FYI, I am located in New Zealand, so there are not many parts available locally.

Posted: Fri Aug 20, 2010 12:15 pm     Post subject:

it takes a 'seconds' pendulum - 39.4 inches long. you are correct inthat it is a pieice of steel rod with the suspension unit threaded on the top of the rod.
it then attaches by going through the pallet crutch hole and into the slot at the top.

this are pretty much standard fitting so after fitting it should work ok. some need to be adjusted a bit to fit snugly into the hole and slot. you should have minimum play possible in the pallet crutch hole.

you may have trouble getting the rod so use 3mm diameter steel and thread the ends to fit. can't remember what tap size but would have been BA type.

Posted: Sun Aug 22, 2010 10:24 am     Post subject:

Thanks Clockfxr

Thats a great help!

I have found a new suspension spring and a new pendulum flat, both 1/8 whitworth, so that makes life easy, as you say, a length of 3mm steel rod should do.

Just to clarify on the length, I assume the 39.4 inches is the length of the rod and spring combined?
Or is it from the top to the centre of the bob?


Cheers
Dave

Posted: Sun Aug 22, 2010 10:28 am     Post subject:



Scrap this request, I just found the FAQ on pendulum length from Klockit.

Cheers
Dave

Posted: Tue Aug 24, 2010 1:29 pm     Post subject:

From the centre of the suspension to the centre of the bob.

Include the whole of the suspesion - in other words the suspension unit complete but making it a bit longer is good because you cannot (well you can but it's difficult) add but you can remove bit by bit easier to get a accurate timekeeper.

Posted: Fri Aug 27, 2010 9:08 am     Post subject:

agreed. Adding is possible, but hard and damn ugly.

I have purchased a new suspension spring and also a new slide, as the one i have is so damaged that adjustment would be near impossible.
I will make a steel rod to length.

I will start a couple of inches over length, and trim down from there.

For now I am on to cleaning and waxing the body of the clock, and thats a whole load of work in ists own right!

Cheers
Dave