400 day clock pendulum spring.

[ftwizard]

I need to replace the pendulum spring (the one the balls hang on) on a 400 day clock. Does the new spring have to be exactly the same thickness, or can there be a bit of leeway.

 

 

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[oldhippy]

If it is a wind up it is essential to have the right s/spring and the same goes for the length. Also the block that goes each side of the anchor (long stem) has to be in the correct position.  This book is the clockmakers/repairs bible when it comes to these clocks. A photo of the clock would be nice and one of the back plate.

The Horolovar 400-Day Clock Repair Guide 6th Edition By Charles Terwilliger

[ftwizard]

The spring is still in place, so I can measure it, but it’s such a small measurement, I wondered if it had to be exactly right, will one or two thou” either side matter that much?

[Tmuir]

Can you give a good photo  of the back plate and the height and width of the plate and we can look it up in the book oldhippy mentioned above and give you the correct size wire. But that is only half the job fitting everything onto the new wire has got to be in the exact positions too as a few mm out can be the difference between it working or not

[oldhippy]

The spring is still in place, so I can measure it, but it’s such a small measurement, I wondered if it had to be exactly right, will one or two thou” either side matter that much?

Try and get it as close as you can. Any change in length and the clock will need regulating, to high = to fast, longer = to slow The clock also has a locking device so it still needs to be able to lock if moving with out kinking the s/spring. Make sure you don't bend the new spring 

[ftwizard]

Thanks for the answers so far.

So, length wise, I can put it all back together exactly the same as it came out, no problem.

I just need to order the correct thickness. I've measured the existing one at 0.0020" would it matter if I bought a slightly thicker one, say 0.0025 or does it have to be precisely the same?

The reason being the measurement I take, may not be exactly right, being as it's such a small dimension.

[oldhippy]

1 hour ago, ftwizard said:

Thanks for the answers so far.

So, length wise, I can put it all back together exactly the same as it came out, no problem.

I just need to order the correct thickness. I've measured the existing one at 0.0020" would it matter if I bought a slightly thicker one, say 0.0025 or does it have to be precisely the same?

The reason being the measurement I take, may not be exactly right, being as it's such a small dimension.

If you can give us a good clear photo of the back plate sugggested by Tmuir, he will be able to look up the exact s/spring needed. Sorry I’m unable to do so as I no longer have my book.

 

 

[clockboy]

It is essential that the spring is the correct thickness and the correct length. If you move away from the spec you will runout of adjustment. This book is a must for the 400 day clocks;

The Horolovar 400-Day Clock Repair Guide 6th Edition By Charles Terwilliger

[ftwizard]

2 hours ago, oldhippy said:

If you can give us a good clear photo of the back plate sugggested by Tmuir, he will be able to look up the exact s/spring needed. Sorry I’m unable to do so as I no longer have my book.

 

 

Okay. I'll do that tomorrow. Thanks.

[ftwizard]

Dimensions of backplate are:
Width = 43.69mm, 1.7205”
Height = 69.76, 2.7465”




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[oldhippy]

That is what’s needed. I’ll tell you how the book works. Tmuir will look up Kundo, you have the designs of the back plate and the positions of all the holes which consist of the train wheel holes and the screw holes. It gives the s/spring the thickness and the position of the blocks and the length all in a diagram. So when it comes to fitting the new one you cut to length, line it up alongside the diagram fit the blocks in position. Fit into the clock and if all is well that’s it.  

[Tmuir]

That looks like plate 1407H Kundo 4 ball midget clock circa 1965

Use 0.0022" (0.056mm) Horolovar you want.

Page 133  in the 10th edition if someone else wants to double check.

It should do 10 beats a minute when set correctly.

Make sure you mark out the exact dimensions and the placement of the parts on the spring, or you can buy a complete replacement unit '5F'

https://www.cousinsuk.com/product/kundo

[oldhippy]

Thank you Tmuir for the info. I would buy the complete unit, it will save you having to sort the blocks out. You will be able to just fit the unit in.

[ftwizard]

1 hour ago, Tmuir said:

That looks like plate 1407H Kundo 4 ball midget clock circa 1965

Use 0.0022" (0.056mm) Horolovar you want.

Page 133  in the 10th edition if someone else wants to double check.

It should do 10 beats a minute when set correctly.

Make sure you mark out the exact dimensions and the placement of the parts on the spring, or you can buy a complete replacement unit '5F'

https://www.cousinsuk.com/product/kundo

Thank you so much for finding that information for me. Not only is it valuable data, but I've learnt a great deal also.

I'm going to get the spring material and rig it up myself. Simply because I've not done it before. I'll probably never do it again either.

[oldhippy]

These clocks are very temperamental and run on very little oil. So if you have trouble do not reach for the oil can as you could cause more problems. Let us know how thing are. Good luck.  

[clockboy]

Agree with oldhippy. I have repaired and serviced a lot of these 400 day clocks. Everything has to be as near perfect as possible for them to run. As oldhippy say very little lubrication is required. The suspension spring must be perfectly straight with no twists or kinks. It must also be in perfect beat or you will find it will only run for a few days. However I do like them a lot and the book I referred to in an earlier post is essential.

The Horolovar 400-Day Clock Repair Guide 6th Edition By Charles Terwilliger

[Tmuir]

Its up to the the 10th edition now. :-)

 

[ftwizard]

10 hours ago, clockboy said:

It must also be in perfect beat or you will find it will only run for a few days.

That's what's happening. How do I make sure it's in beat? I was just doing it by eye, didn't know it was so critical. I've only done watches up to now. Can I check it on the timegrapher?

 

[oldhippy]

When the clock escapes watch and see how far the balls carry on. It needs to be the same when the balls rotate back. It needs to escape the same amount in both directions for the clock to be in beat.    

This should help

https://www.youtube.com/watch?v=e6vZBxaK7Bs

[ftwizard]

Very good. I'll give that a go tomorrow. Thanks.

[ftwizard]

Another couple of questions if you don't mind. Where are those measurements taken from i.e.. from the centre of the pivot to the top of the fork, or from the bottom of the plate to bottom of the fork. I've set it as stated and the amplitude seems very low at about 170.

What would be a fair amplitude for this clock? Before I fiddled with it, it was about 280.

[oldhippy]

Sorry I can't help with this one.  You need to ask Tmuir. You could message him.

 

[clockboy]

1 hour ago, ftwizard said:

Another couple of questions if you don't mind. Where are those measurements taken from i.e.. from the centre of the pivot to the top of the fork, or from the bottom of the plate to bottom of the fork. I've set it as stated and the amplitude seems very low at about 170.

What would be a fair amplitude for this clock? Before I fiddled with it, it was about 280.

What measurements are you referring too.

 

[ftwizard]

5 hours ago, clockboy said:

What measurements are you referring too.

 

The suspension spring. 5F

[Tmuir]

Have a look at the Couins link I gave above it has the measurements on it

Edited June 9, 2018 by Tmuir