Clutch spring on a metronome (I know it's not strictly a clock) question

[Rixy]

I know it's not a clock but it does go tick and is clockwork, so I hope you will forgive my question. Have been restoring a metronome for my sister. It's a fairly simple construction, German made in the 50s I think. Where I would expect to see a ratchet by the winding arbor, there is a spring 'sleeve' that I think acts like a clutch when it is wound. There is a little hook to attach the spring (see pic) but the spring was short so I unwound it a bit and bent it round the hook. Gave it a wind and it held and the pendulum allowed proper escapement so got a ticking for about 5 seconds then the clutch spring snapped by the hook. 

Am I on the right track with how this sort of clutch spring works and where would I find a replacement?

Have added quite a few photos so you can get a better idea.

[watchweasol]

Hi. I suppose there are parts suppliers for these metronomes but failing that maybe make one from guitar strings. I know some members use them for making click springs.

[oldhippy]

I would say the ratchet wheel and click would be on your bottom photo. The click would have a tail spring which would fit in the part that is high because at the moment it is doing nothing,  I would say the click would be held by some sort of split spring. 

[Rixy]

Thanks for the feedback. I'll keep going!

[watchweasol]

Looks like the spring is a torsion type anchored by the raised lug on the plate and held by the ither end on the frame, tensioned by movint the lug end. this tightens the spring on to the shaft to act as the clutch.  I think.  the attached picture may be of help.

[oldhippy]

For that movement yes. But it is not the same as the original. 

[watchweasol]

Absolutely the picture was attached as an example as to how they may be fixed, it all depends on the model and maker of the instrument and the design. It is pretty obvious that it’s different from the one supplied by the OP but with nothing to compare it with I supplied a picture for reference.

 Do you have a maker of the instrument ?    Wittier of Germany seems to be the main European maker.

[Rixy]

It says 'System Maelzer' on the case, but I have just checked out Wittner and they seem to be the manufacturer of this sort of metronome. (Maelzer, according to good old Google, was the inventor of that type of metronome). They don't have online shopping but there is an email address so have got in touch with them. I'll let you know if I get a reply. Thanks, Watchweasol.

I have attached a picture of what remains of the spring looks like and the label on the case.

 

[oldhippy]

Here is the same movement and you can see what is missing.

[Rixy]

That's really helpful, thanks OH. Looks like I will need two nuts as well. Are threads standard or will it be difficult to find?

[oldhippy]

I honestly don't know.  

[Rixy]

I heard back from Wittner. They said the metronome was made in East Germany in the 50s and that they do not have replacement parts for them. Guess I'll have to be inventive.  If I can find a torsion spring with an internal diameter of 3mm and nut that will fit the thread and hold it in place, I might be on to something. 

Otherwise, I'm going to get a battery powered one and go back to clocks

[watchweasol]

Was very good of them to supply the information, these days a lot just ignore enquiries from individuals.   Be inventive and good luck Iam sure you will succeed.