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Sizing hands

Bonefixer
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Bonefixer WRT Addict

Bonefixer

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I bought an old Oris to service/restore, and the minute hand was wrecked - no idea what happened to the watch, but the hand was bent by 90 degrees at the tube, the dial feet had sheared off the dial, but otherwise the watch was ok and runs. 
 

I'm going to service it and sell it on via eBay. I need new hands. How do I measure them? Using my callipers I know that the minute hand should be 0.8mm. But Cousins don't do this size - a bit smaller at 0.7 seems very common. Is it normal to get 0.1mm less than the cannon pinion to get it to friction fit, will I need to broach it, or should I look elsewhere for a hand that is just right?

AndyGSi Distinguished Member

AndyGSi

Posted
Posted (edited)

There are lists showing hand sizes for different movements if it's not stated on the movements data sheet.

Edit

In answer to the second part it's always best to get the correct size hand if possible.

Photos would help guide you.

 

Mechanical Hand Sizes.pdf

Edited by AndyGSi
Bonefixer WRT Addict

Bonefixer

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Thanks for the tip. My movement wasn't on that list you posted, but I found a data sheet elsewhere and have managed to find a pair of hands at 1.3 and 0.8 mm as they're meant to be. 
 

I have a similar issue with a 7750 Chronograph I'm trying to get new hands for. This is an ETA movement, not a Chinese copy. The pinion diameters are well documented. I bought a set of 7750 hands from ebay - wouldn't fit. I bought some centre second hands at 0.25 diameter from Cousins. Wouldn't fit. Cousins, not anywhere else as far as I can find, don't have subdial hands at 0.18mm. 
 

What next? Attempt broaching, not easy when trying to expand a 0.17mm hole by 0.01mm? Or get a bigger size and try and squash it a bit, or glue (I know, I know, banish me to watch fiddlers hell for even suggesting it)

AndyGSi Distinguished Member

AndyGSi

Posted
Posted (edited)
28 minutes ago, Bonefixer said:

not anywhere else as far as I can find, don't have subdial hands at 0.18mm. 

They are available

https://gleave.london/sub-dial-hands/

28 minutes ago, Bonefixer said:

I have a similar issue with a 7750 Chronograph I'm trying to get new hands for. This is an ETA movement, not a Chinese copy. The pinion diameters are well documented. I bought a set of 7750 hands from ebay - wouldn't fit. I bought some centre second hands at 0.25 diameter from Cousins

I can't comment on the eBay ones but don't understand why the Cousins won't fit.

Is the pinion OK and what tools are you fitting the hands with?

Edit

Can't vouch for this site but there are others that also sell individual or sets.

https://www.shop.sk-watchparts.com/epages/Starck_Andreas44894456.sf/en_GB/?ObjectPath=/Shops/Starck_Andreas44894456/Categories/"Zeiger für Armbanduhren"/"ETA 7750"

https://www.shop.sk-watchparts.com/epages/Starck_Andreas44894456.sf/en_GB/?ObjectPath=/Shops/Starck_Andreas44894456/Categories/"Zeiger für Armbanduhren"/"ETA 7750"/"Zeigersätze ETA 7750"

Edited by AndyGSi
Bonefixer WRT Addict

Bonefixer

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Thanks again. I'd not come across Gleave before, but they don't have the right ones - 6mm for the sub dial hands is too big for me. I found the sk shop (European somewhere) and the ones I want are out of stock. 
 

As for Cousins, the h and m hands are perfect. But they don't do 0.18mm, and the 0.25 centre hand doesn't fit. There's nothing wrong with the pivot - it's a new movement I've harvested from a NOS watch I got on ebay. I've not stripped it down, and the hands I took off go on easily as they should. I use Horotec levers and a sheet of poly to take hands off, and put them on with tweezers and a gentle press. 
 

I'm surprised how difficult this is proving given how common the 775x family of movements is. Even if ETA don't sell unless you belong to them in some way, I can't understand why there aren't plenty of others that will. 

Neverenoughwatches Distinguished Member

Neverenoughwatches

Posted
Posted
3 hours ago, Bonefixer said:

What next? Attempt broaching, not easy when trying to expand a 0.17mm hole by 0.01mm? 

Its surprising how easy broaching out a hand hole is, a 10 micron increase in diameter shows up quite visibly as a distance travelled up a thin tapered broach. I just pick what I need from a large selection of preowned hands and make them fit.

  • Like 1
AndyGSi Distinguished Member

AndyGSi

Posted
Posted
15 minutes ago, Neverenoughwatches said:

Its surprising how easy broaching out a hand hole is, a 10 micron increase in diameter shows up quite visibly as a distance travelled up a thin tapered broach. I just pick what I need from a large selection of preowned hands and make them fit.

It's a different case though with Chronograph tubes don't you think?

  • Like 1
Neverenoughwatches Distinguished Member

Neverenoughwatches

Posted
Posted
23 minutes ago, AndyGSi said:

It's a different case though with Chronograph tubes don't you think?

Broaching out sweep seconds and sub dial hands are definitely not as easy as hour and minute hands. The blind hole tubes take more time with a little trial and error sometimes but still doable. Chrono hands I haven't tried so I'm not sure though, I imagine them to be the most difficult needing the tightest fit.

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