# Small clock spring



## paulfrazer (Jun 10, 2020)

I have some experience of repairing clocks of mantle size, but a friend has asked whether I can repair a small clock from his 1938 car. He thought that the spring had broken which is sort of true, but the actual problem is that it has become disengaged from the barrel. In the clocks I am used to the end of the spring has a hole in it which engages with a hook made from an tab cut into the barrel. This is similar but the end of the spring itself has been bent back to form a hook which is supposed to engage with the barrel.

The end of the spring had broken off so I heated it and made a new bend in it. I cannot, however, get this to engage wit the barrel hook which seems to be very close to the barrel.

I am not sure whether my new spring end is the problem or whether the barrel hook should be more prominent. I am wary of attempting to bend the barrel hook more for fear of breaking it off completely. I did not "quench" the spring after I had heated it but the original seemed to be quite hard so maybe I should have done.

Can anyone offer advice? Are new springs available with a bent back end? I have never seen one, but then I have only dealt with much bigger springs and barrels - taking my life in my hands as I don't have a spring winder!

Thank you

Paul


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## simon2 (Dec 5, 2010)

Several questions. 1. Are you saying that a small section of the barrel wall has been punch in, to form a hook, and that that section is laying to flat to the inside of the barrel wall .If that is the case then by gently easing it out to protrude deeper into the barrel, is possible if done gently. 2. If you heat treated the last centimeter of the spring ( keep the heat on the end of the spring, as you bend it back on itself) the bend would be tighter and enable the outer coil of the spring to lay closer to the inner wall of the barrel. Shaping the end of the spring to form a Chisel end, by stoning it on an Oilstone will help to engage with the hook. You could drill and pin the barrel wall to form a new hook. With practise a mainspring can be wound into the barrel, by hand. It does take a time and you do have to be careful, but possible.

Hope this helps. if not then, shout.

Regards Simon.


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## paulfrazer (Jun 10, 2020)

Thank you Simon.

Yes a small section of the barrel has been punched in to form a hook. Looking at it closely I think that it has got flattened and a bit mangled by the end of the spring turning round over it without catching. I feel that it would help if it was made to protrude more but it is quite small (by my standards!) and I am not sure how to do it. I measured the spring and it is 8.5 mm high 0.22 thick and the barrel is 17.72 mm in diameter. I wondered about trying to tap it but I am concerned about distorting the barrel and/of breaking the hook. Is there any sort of technique to do this?

I will have a go at sharpening the end of the spring to try to get it to engage with the hook.

If it came to making a new hook is there any information about how to do this?

Fortunately the spring isn't strong so it is quite easy to get it into the barrel. I have done it with much stronger springs using leather gloves and some holding of breath but it isn't may favourite job!

Paul


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## simon2 (Dec 5, 2010)

A small punch, or even an old blunt small screwdriver should do the trick. Hold the Barrel in a vice and apply, light taps to the end of the hook.it should slowly move towards the centre of the Barrel. Just enough for the end hook of the mainspring to tuck behind it. If all fails then repin the barrel.


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## nevenbekriev (Apr 21, 2019)

Hi Paul,

Can You pleas show a picture of the spring end and one of the hook inside barrel? This is a large barrel (compared to those in pocket and wristwatches) and there is no problem to form a new hook, there are different ways to do that, but let us see if this is needed or not.


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## paulfrazer (Jun 10, 2020)

Thank you for the replies. I did try tapping it with a light hammer - and managed to break the hook off altogether  .

Here are some photos. It isn't a watch but a small clock from a 1938 Daimler car. If there is any way of putting a new hook in the barrel I would be very grateful indeed to know how it is done. The owner would understand about what had happened but it would be good to let him have it back in working order.

I have just realised that I don't know how to add photos from my computer. Can anyone help. please?

Thanks

Paul


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## paulfrazer (Jun 10, 2020)

Just managed it!


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## paulfrazer (Jun 10, 2020)

Is anyone able to help regarding a new hook on the barrel?


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## nevenbekriev (Apr 21, 2019)

I just copy-pasted it from an old book:

To fit a new mainspring hook to a barrel, first drill a hole in
the side of the barrel at a slight angle pointing away from the
direction of pull of the mainspring. The hole is then threaded
slightly undersize.
Taper a piece of steel wire by filing and cut a thread with a
screw plate, holding the wire in a pin-vice. Remove the pin-vice,
cut the wire close to the screw plate and shape the protruding
piece of wire into a hook by filing.
Unscrew the threaded wire from the screw plate and insert the
small diameter end of the wire into the hole in the barrel entering
from the inside.
The protruding wire on the outside is now held by the pin-vice
and the wire is screwed into position by unscrewing from the
outside.
The hook should project into the barrel a distance no greater
than the thickness of a piece of the mainspring.
When in place remove the pin-vice, cut off the wire on the outside,
file down close to the barrel and finish with an oilstone slip.


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## Dell (Nov 24, 2019)

paulfrazer said:


> Is anyone able to help regarding a new hook on the barrel?


 Hi Paul when I replace a hook in a torsion spring barrel I drill a hole on the other side to the original hole after pegging the original hole with brass and silver solder to give it its strength after drilling new hole I lightly counter sink the out side of said hole, I then turn a new hook on the lathe , although it doesn't look like a hook, it looks like a small nail with a step in the shaft, so people use a small nail and make the hole very slightly smaller , put nail in from inside and rest it on a chisel set in vice then use a punch with a hole in just big enough to go over the protruding nail shaft, drift it in until the head is close to the inside of the barrel but enough to catch the spring then cut the nail shaft off bet leave it 1mm proud put it back on the chisel still in vice and pean the shaft into the counter sink that will stop the hook pulling out.

i don't know where you are if in UK I can turn you up a hook but you will need to determine what size you need, that's if you don't want to use a nail but I think that is your best bet.

Hope this helps Dell


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## nevenbekriev (Apr 21, 2019)

Hi, all

Yes, this is a good way to make a new hook, which is used mainly in big clocks.

@Dell: My advice is not to solder the old hole with silver solder. Pegging is needed only for aesthetic reasons, which is reasonable in torsion clocks. Hearing drum to temperature of solder melting will make the brass soft. We don't need that as teeth may bend by the torque of the spring. Using of soft led-tin solders will not soften the brass.


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## Dell (Nov 24, 2019)

Most of the clock barrels I repair are due to a spring letting go and the barrel invariably ends up with a split, that is the reason I use silver solder because it has more strength than soft solder, the barrel will time harden anyway and I always planish the soldered joint Before filling and polishing so that work hardens it as well but you are correct the heat will soften the brass that's why I never wind a clock past 1/2 way to start with.

i have never had one strip the teeth but I understand what you are saying.


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## nevenbekriev (Apr 21, 2019)

Hi Dell,

Yes, when there is a crack in the cylindrical part of the barrel, this is really bad. But even then, it is better to turn a ring out of steel tube and press it on the barrel. Of course, if there is enough space for this ring in the movement.

I know the theory that brass will harden 3 days after heating, but I am not sure if it is true. May be some sorts of brass really harden a little, but I have seen a lot watch or clock wheels, that somebody has heated (in order to anneal the steel pinion to ease drilling for re-pivoting), where the brass table of wheel has become soft and good for nothing. And no time hardening happens there at all.

Another option when barrel has crack is to make entire new barrel, or which is a bit easier - to cut the cylindrical part, to turn a new one and solder it in place with soft solder.


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## Dell (Nov 24, 2019)

Hi nevenbekriev

the trouble with using a steel ring pressed over the barrel is I restore torsion clocks with glass dome you would be able to see it , and I am not confident enough yet to make a new barrel, I say yet as hopefully I will be one day.

Dell


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## nevenbekriev (Apr 21, 2019)

Here are some pictures I took when making clock barrels. They had to be two and equal.



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## Dell (Nov 24, 2019)

Hopefully I can do that one day.

Dell


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