Click Spring for Sandoz Clock

[GreyProtocol]

I've been working on an 8-day clock. The dial is decently large, but the actual movement is similar to an oversized pocket watch. The only markings I've been able to find are "Sandoz" on the dial, and on the barrel bridge:

An "M" with emphasized serifs

"15 Fifteen Jewels", "3 Three Adjustments", and "Made in Switzerland"

The serial number 403250

While working on it, the click spring went *ping* into oblivion, and despite my best efforts and strongest magnets, I haven't been able to find it again. At this point, I'm looking to replace it. However, just going off the above markings, I haven't been able to find any information about the movement classification or caliber in order to find a proper replacement. Since it's a click spring, I'm not too concerned about getting an exact replacement just so long as it applies pressure to the click. The original was just a simple spring consisting of a single U-bend and fit into a channel 8.4mm long, 2.9mm wide, and 0.54mm deep.

How would I go about finding more information on this movement in order to get a proper spring? Or just search for springs that have the right shape and dimensions?

[RogerH]

Hi and welcome to the forum. You're right about the movement as Sandoz mainly deal in watches although Sandoz Swiss is supposed to be the better quality. getting spares however could be tricky unless someone else knows of a specific place your best bet will be the likes of Ebay or auctions to try and find something similar and adjust it to fit. It may be possible to make one from scratch but without the original as a template that could be a bit hit and miss.

[oldhippy]

Here is a picture of assorted shapes of springs to help in what you need I have marked it with a red arrow. This should give you an idea of what you are looking for. If you make one make sure it is of a good strength and be careful of the height you don’t want it rubbing the underside of the ratchet wheel.    

[GreyProtocol]

20 hours ago, oldhippy said:

Here is a picture of assorted shapes of springs to help in what you need I have marked it with a red arrow. This should give you an idea of what you are looking for. If you make one make sure it is of a good strength and be careful of the height you don’t want it rubbing the underside of the ratchet wheel.    

Would you recommend, then, just buying an assortment of springs and picking one that looked best?

My primary concern is over size, since the movement is something between a clock and a watch. I don't want to purchase a spring that looks right but turns out to be intended for a watch and far too small.

[oldhippy]

This photo is of different springs for watches. I don't think suppliers keep assortments for the type of clock you have. I would advise you make yours following the shape I have pointed out. You could try ebay old stock and assortments of old stock are always on there. 

[Tmuir]

I have heard of people making click springs from guitar strings, but that was for watches not clocks, but any suitable sprung material would do. Do a search on 'spring steel', or look up any local model engineering supplies.

Besides stainless steel you can also buy phosphor bronze wire for winding your own springs which would work also.

You would need to work out what diameter (gauge) would be the best, but here is a place that sells stainless steel and phosphor bronze spring wire.

I don't know where you are but this company is in the UK and I've bought from them many times and they post out to me in Australia.

https://www.ajreeves.com/phosphor-bronze-spring-wire.html

 

The 27SWG stainless steel is about 0.42mm, you would need to do some carefull measurement to see if this is fine enough.

If you need to go finer look at guitar strings, they go down to 0.23mm for the super extra light 'E' string