How to service a tourbillon (ST8000)

[Logixa]

Hi all,

Since it was impossible to find a how-to guide for servicing a tourbillon (in this case the seagull ST8000) on the internet, I decided to create one myself and share it on a couple of places on the internet. I hope you guys enjoy it and it will help you in the future.

There are basically 2 types of tourbillons (other than multi-axles ones)
1. The brequet carroussel type (big balance wheel, turns 360 degrees around his own axle in 1 minute)
2. the blancpain flying type (the whole escapement and balance turn 360 degrees in circles like a planet in a minute)

This is the blancpain version and is made by Seagull. I purchased this watch myself, both for the beautiful looks of an tourbillon and to do a service

 

Conclusion:
The tourbillon cage can be tricky as it requires balancing multiple loose parts before they can be screwed tight. Timegrapher cannot be used on tourbillons as the moving of the cage+balance will give readings going up and down at the same time, same goes for amplitude. Current timegrapher are just not made for tourbillon timing. It can only be timed in an old fashioned way, after 24h's checking. The ST8000 is very well made, be it Chinese. Finishing of gears and plates together with the thickness of materials makes it sturdy and built to last.

 

 

Edited December 23, 2020 by Logixa
added pictures

[oldhippy]

Very good and nice clear photos. Just one thing you forgot to mention and that is make sure you have all the power off before dismantling the movement . We don't want parts flying all over the workshop do we. Happy Christmas and stay save. 

[Nucejoe]

Wow, thanks for sharring.

Happy christmas.

[clockboy]

Great post with clear pics. Also a great watch movement indeed thanks for sharing.

 

 

[jdrichard]

Great work, thanks

[spectre6000]

Good writeup. What is the purpose of that top plate though? It looks like it just adds unnecessary thickness to the movement.

[Logixa]

Haha good point @oldhippy

 

@spectre6000
Yes you are right it does add a lot of extra thickness to the movement. They could have made the top plate a lot thinner, like the ones you see on a Rolex 3135. I understand that it's useful for keeping the hour wheel down, but the thickness is unnecessary.

[Logixa]

Oh I just realized the thickness of it is needed in order to create enough clearance for the tourbillon as it sits quite high.

[spectre6000]

Usually the dial does that. Is the thickness of the tourbillon necessary, or did they make it extra thick to pop through the dial like they like to do with a lot of the Chinese watches on Ali-X?

Also, am I correct that the plates are entirely finished with perlage save the super deep Sea-Gull cotes de Geneve? That's super unusual for a Chinese movement. 

Can you go into more detail on the perceived quality of the movement? 

Also, I've thought about this a few times in the past but never had a reason to ask out loud: how do you go about timing out a tourbillon? This one at least doesn't have a hacking complication. Do you just stop in manually, adjust, and keep going, or is it easy enough to regulate it while it's moving around in the cage?

[Logixa]

I think they could have made the whole tourbillon max 1mm thinner. Any thinner than that and it you would get issues with the parts not having enough clearance to make it a mass produced item. Plus, I think that this flying tourbillon type is in nature quite high due to its construction in comparison to a carousel type. Now i havent had a carousel type before in my hands to service but I will receive 1 from someone on another forum to service it for him. I'll make pictures of that one too and compare the constructions vs the sizes. Right now the tourbillon is sitting flush with the dial

Yes you are correct that every part of the movement has perlage and the backside a quite deep cotes de geneve. It is the best i've seen so far on any chinese movement.

The quality of the movement is good. The finishing of even the gears is nice and all parts feel sturdy and not filmsy.

Timing is hard with a tourbillon. You have to place it on one of those watchmakers turning machine, forgot the name its those things where you can place like 6 watches on at the same time and the whole device turns while also turning the watches 360 degrees on the axle. After 24h's you get a sense of what the deviation is. Next up is manually stopping the tourbillon, be it by removing the power or fixating it with a tweezer and then adjusting it.

Plus, it has no hacking so you would need to write down what the difference in time.is was in comparison with the watch when you set the time.

Edited December 24, 2020 by Logixa

[Michael]

great job. Well done and thanks