# The Smallest Tuning Fork Movement



## Silver Hawk (Dec 2, 2003)

I've been working on a couple of these recently and don't have any pictures on my website of this movement (soon to be rectified!) but I believe this little Bulova Accutron 2210 is the smallest tuning fork movement ever produced.

Quite difficult to work on...virtually every operation seems to require an almost total strip down of the movement. Some clever design features in this: the tuning fork going either side of the central battery, several worm gears to change the direction of the train through 90 degrees...all to save space. It took the obsolete 388 battery; there is no modern equivalent of this size, so you now have to use a 329 with nylon spacer.

So how do they design these things without the aid of CAD...was it trial-and-error?


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## jasonm (Nov 22, 2003)

I bought this one from Roy some years ago for Alyson, they are very small indeed....

I need to send it down for a battery change if thats OK Paul..


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## Silver Hawk (Dec 2, 2003)

jasonm said:


> I need to send it down for a battery change if thats OK Paul..


Sure Jason.


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## foztex (Nov 6, 2005)

great pics Paul,

they are real marvels. I've always fancied a 2210 but have yet to find one that appeals. The compactness is incredible, without CAD they just drew them I suppose, with plenty of use of a rubber 

Andy

PS, try and be more careful mate and wipe the blood off that battery clip before you re-case it :thumbsup: B)


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## Silver Hawk (Dec 2, 2003)

foztex said:


> PS, try and be more careful mate and wipe the blood off that battery clip before you re-case it :thumbsup: B)


 :lol: As you well know, that's insulating paint to stop the clip shorting on the case....but why cant I find anything today that sets as hard as this? Araldite never sets this hard. Was it baked / stove enamalled on? :huh:


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## Who. Me? (Jan 12, 2007)

Silver Hawk said:


> foztex said:
> 
> 
> > PS, try and be more careful mate and wipe the blood off that battery clip before you re-case it :thumbsup: B)
> ...


It looks like the dope/varnish that they applied to the coils.

Wonder if you could get it from wherever vintage radio enthusiasts buy it?

They must use it when rewinding coils?


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## jeffvader (Jun 10, 2008)

It's shellac & it's still available. It's a resin secreted by the female lac bug.


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## Silver Hawk (Dec 2, 2003)

jeffvader said:


> It's shellac & it's still available. It's a resin secreted by the female lac bug.


Jeff, definitely not shellac on the battery clip. I think they only used shellac to glue the jewels on the end of indexing pawls.


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## Pegwood (Jan 26, 2009)

Silver Hawk said:


> Jeff, definitely not shellac on the battery clip. I think they only used shellac to glue the jewels on the end of indexing pawls.


The index and pawl jewels were attached using heat cured epoxy cement according to Bulova at the time.


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## foztex (Nov 6, 2005)

Silver Hawk said:


> jeffvader said:
> 
> 
> > It's shellac & it's still available. It's a resin secreted by the female lac bug.
> ...


I must say Hawkey I reckoned it was shellac too, mainly 'cause of the red colour. Hows about heating some hard plastic so it's liquid and applying a drop of that? failing that the paper weight resin we were chatting about the other day?

Andy


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## Larry from Calgary (Jun 5, 2006)

foztex said:


> Silver Hawk said:
> 
> 
> > jeffvader said:
> ...


Paul,

It looks like it could be the same material they use to seal or tropicalize electronic circuit boards.

Larry

:umnik:


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## johndozier (Mar 2, 2008)

Loctite maybe?


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## feenix (May 27, 2008)

Plastic Padding do a Glass Fibre filler. Perhaps that will do what you want?

Try putting 'resin' into the search engine on RS Components site.


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## jasonm (Nov 22, 2003)

Hardest substance known to man, a piece of dried on Wheatabix .......


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