Certina 25-651 date change trouble

[bsoderling]

Hi guys,

 

Been servicing a non-running Certina New Art for a friend. Everything has been going well with proper time keeping and date change etc.

 

Was just going to set correct time and date when I suddenly realize that date isn’t changing anymore.

 

Sigh....opening up againg and realizing that the tiny spring mounted inside the date change wheel is broken. The function is pretty simple; the spring pushes the date wheel forward to change date forward and bend to slip over the date wheel teeth when crown is moved backwards.

 

I attached a couple of photos of the parts.

 

I bet this is not an uncommon problem with these movements as the spring is really ”weak” and not made of material I’m used to see as spring material

 

The complete wheel with spring in place is apparently labelled 2556 and obsolete at Cousins, where I usually find parts.

 

I found one seller on ebay but price with shipping goes way beyond what my friend would like to cough up to get this going.

 

Questions:

 

Any ideas towards alternative sources for a 2556 part?

 

I ”think” I could probably bend together a spring to reasonably fit and function. But the weak material will be an issue. Any thoughts and ideas on that?

 

I guess I could make a ”spring” of stiffer material and probably accept that the fast date change by moving the crown backwards won’t work. My friend would likely accept that.

 

Feedback and ideas appreciated!

 

 

 

 

 

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[watchweasol]

Hi  It looks like a copper spring If so could be repaired  by soldering a bridge across the break or Alternativly make another spring or source a doner movement off the bay. repaired carefully and tried it will probaby work ok.  I myself would try the repair route as there is nothing to loose and if it fails you still have the spring as a pattern to make another..    

[bsoderling]

Copper sounds very plausible. And should be solderable. But the small, broken off part is probably
Donor movements seem hard to find and prices are high, even for the may or may not work ones. I saw one and was able to zoom in on my part,and what do you know ; spring looks broken...

I will see what I can bend together. Maybe an old scrapped h/s will work as material?

Thanks for feeding my thoughts with new ideas here!




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[bsoderling]

Words got lost there.

I meant to say that the broken off part is less than a mm and I will probably drown the whole thing in solder.


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[rogart63]

They are made of copper berylium . Same as in old hairsprings . If you find a hairspring same size you can make one. Never done it myself but one day i probably will have to it. There is a thread on klocksnack about this date wheel . And at the end someone made a new spring. https://klocksnack.se/threads/certina-25-651m-urverket-byter-inte-datum.15157/page-4#post-3081598

 

https://uhrforum.de/threads/certina-kal-25-652-feder-gebrochen-beim-datumsschaltrad-hilfe-tipps.237604/#post-2914045

 

Edited November 9, 2019 by rogart63

[bsoderling]

Thanks Rogart, was almost hoping to see you jump in on this post, and there you are... :-)

That Klocksnack thread was right up my alley. For some reason I never joined that forum. Stupid, being Swede and all. Will jump in there now.

On the topic, when you say ”old h/s” is that old as pocket watch or will my stash of regular messed up watch h/s do for a start?

h/s material has made me wonder since I got started on this hobby. It’s weird that such a delicate thing can work with with material ranging from soft as butter to stiff as steel. At least that’s how I have experienced when trying to correct them...





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[rogart63]

4 hours ago, bsoderling said:

Thanks Rogart, was almost hoping to see you jump in on this post, and there you are... :-)

That Klocksnack thread was right up my alley. For some reason I never joined that forum. Stupid, being Swede and all. Will jump in there now.

On the topic, when you say ”old h/s” is that old as pocket watch or will my stash of regular messed up watch h/s do for a start?

h/s material has made me wonder since I got started on this hobby. It’s weird that such a delicate thing can work with with material ranging from soft as butter to stiff as steel. At least that’s how I have experienced when trying to correct them...





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In my experience the vintage hairsprings are softer in material then the newer ones . Have tried to fix som old Omega and Tissot hairsprings  . Sometimes they are  so easy to bend that if you sneeze they are gone .  Think normal watch hairsprings will do Around 10, 5 ligne . I read somewhere that Certina use copper berylium in the springs. And i have some old boxes of hairsprings with that material.  So if you need some material i can have a look. 

[bsoderling]

Close to giving up on this one....

Have tried a couple of h/s and the material is fairly easy to shape but way to soft to enable pushing the date wheel forward. They simply bend backward.

Trying some very thin click spring wire but these are so springy that they are hopeless to get in shape and stay in place when put into the wheel.

A last resort may be to ”glue” in a short, straight piece with shellac to push the date wheel forward. Will disable the quickset function when winding backwards, I guess.

Anyone out there with a spare movement not needed, let me know. Maybe we can work something out.







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[CaptCalvin]

You can try annealing the click spring first by burning it red hot and letting it air cool then you can bend out to any shape you want. Make sure you take it off the flame as soon as it starts glowing otherwise you risk turning the whole thing into ash. Harden it again by making glow red hot and then quenching it in water to harden it again. Then temper it to take the brittleness out by heating and air cooling at some temperature. What this temp is I don't know but definitely not to the point where it glows red hot again otherwise you would just be annealing it again. Maybe someone more knowledgeable about heat treatment can chime in.

Or maybe you don't even need to bother with hardening and tempering? Since the original spring appears to be copper maybe tensile strength isnt a priority?

Edited November 11, 2019 by CaptCalvin

[jdm]

33 minutes ago, CaptCalvin said:

What this temp is I don't know but definitely not to the point where it glows red hot again otherwise you would just be annealing it again. Maybe someone more knowledgeable about heat treatment can chime in.

I'm also interested in the heat treatment of very small parts. I'll be ordering a booklet on the subject but don't know what to expect from it. Sometime it look like one can read and watch from 100 sources but when going to practice things will be different again.

[measuretwice]

I think beryllium copper is the likely material, in non ferrous materials, springs are usually it or phosphorus bronze.   You could engineer a replacement out of steel (say 1095) but the BC doesn't rust which is one of its advantages.

BC is unike any copper you've worked.   Its strength is roughly 4x that of mild steel - it can get up to 200,000 psi for example.  Its heat treatment is also different other copper alloys, which for the most part heat to anneal and work to harden.   Its so strong its used for things like hammer heads and wrenches in no-spark environments

Most stunningly, the stuff can be deadly.  Well ok, a bit of hyperbole there, its safe as a sold, but inhale the dust like might come of from filling, polishing or machining and it does a lot damage up to potentially killing those who have a strong reaction to it.  It don't knowingly let in the shop for fear I'll forget one day and not take precautions.  Perhaps i'm being paranoid as its not a restricted material, and I do not know how much you'd have to breath to be at risk, but it is a nasty material.  I know one account of a guy's son who's health was pretty ruined so I just avoid it.  Just offered as a heads up if working with it.

To make one, perhaps if you could get 302 or 316 stainless foil/sheet?

As for BC, here's  a source for the foil  http://www.goodfellow.com/E/Copper-Beryllium-Foil.html

and heat treat info  https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwi_z8fZ2OLlAhUBneAKHdTRCvcQFjAAegQIBRAC&url=https%3A%2F%2Fmaterion.com%2F-%2Fmedia%2Ffiles%2Falloy%2Ftech-briefs%2Fat0015-0311---tech-briefs---heat-treating-copper-beryllium-parts.pdf&usg=AOvVaw1EAXwjgyEz0P10Yz8By_Gw

 

BC safety  I'd wear a filter mask and for sure use coolant if machining or otherwise cutting it https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&ved=2ahUKEwiOpND43OLlAhXywVkKHePyB1cQFjALegQIABAC&url=https%3A%2F%2Fmaterion.com%2F-%2Fmedia%2Ffiles%2Fcorporate%2Fbesafetyfacts%2Fsf101-safetypracticesformachiningcube.pdf&usg=AOvVaw0SRVup9TS1JAU6aejkKNt5

 

Edited November 11, 2019 by measuretwice