Movement holder for chrono hand setting Valjoux ETA7750

[Knebo]

Hello all, 

I'm well aware that there have been previous threads on this (I've read them), so apologies for opening a new one. 

To sum up the two purposes of a dedicated movement holder for setting the hands, especially the central chrono seconds, are the following:

1. Allow you to press the chrono reset pusher to ensure that the pinion stays firmly at 12 o'clock. 

2. Support the jewels when pushing on the hand, which will require a relatively high force. 

Now, I've bought a Chinese clone of the Horia movement holder, which looks like this:

It works well to hold the movement and also the pushers work. So point 1 is covered. 

HOWEVER, the jewel support pins (point 2) are not quite so good. Particularly with regard to the centre jewel support. 

Here is the clone:

And now the Horia original:

If you look closely, you'll notice that the central supporting pin is thinner on the Horia holder whereas all five are the same on the clone. 

Consequently, on my clone holder, I cannot actually get the pin to go through the screw thread for the rotor and down to the jewel. It will, however, support the bridge. 

I'm getting closer to my actual question.. 

When you look closely at the automatic bridge that holds the jewel, I'm wondering if the jewel can actually move (towards the movement). You see the full jewel size when looking at the bridge from below. However, when looking at the jewel from the top of the bridge, through the thread of the rotor screw, you see less of it.

So, is the jewel "bottomed out" there? Hence, supporting the bridge would suffice? Or is there an invisible gap that allows the jewel to move and it's indispensable to support the jewel itself? 

Thanks in advance!

 

Edited December 16, 2024 by Knebo

[AndyGSi]

I can't answer your question but looking at this from Cousins the others should be different sizes.

Maybe the threads are the same and you can just get these as replacements for your clone?

Edit

The Cousins clone appears to have them all the same size but smaller than yours.

Edited December 16, 2024 by AndyGSi

[Knebo]

Thank you, @AndyGSi, that's a very good point. I didn't think of the replacement pusher/pin. It would probably have the same thread.

 

 

30 minutes ago, AndyGSi said:

The Cousins clone appears to have them all the same size but smaller than yours.

I think they're also too large for the respective hole. 

[AndyGSi]

12 minutes ago, Knebo said:

I think they're also too large for the respective hole. 

They look to me like they're all the same size as the Horia centre pin.

I can't see Cousins selling something that's not suitable.

[Knebo]

11 minutes ago, AndyGSi said:

They look to me like they're all the same size as the Horia centre pin.

I can't see Cousins selling something that's not suitable.

 

I did my basic "photoshop" analysis and I think it's clear that the Horia pin is significantly thinner (relative to the thread).

 

I wouldn't trust Cousins THAT much. However, this may bring me back to the question whether it suffices to support the bridge (instead of the jewel itself). If so, both the Chinese clone and the Cousins tool (which is 100% a Chinese clone, too), will also do the job.

 

 

[Knebo]

So, I finished my service for the 7750

I managed to borrow a proper movement holder with suitable jewel support from a local watchmaker/friend. Didn't want to take any risks on an expensive watch like this. 

Here are some random pics and the final timegrapher outputs :

 

Dial up, full wind

Dial up, full wind, chrono activated

Crown down, full wind, chrono off

 

I'm very happy with the final results of my first chronograph service

[Kalanag]

Well done!