Wittnauer Chrono - Venus 188

[Razz]

First of all I would like to thank the community here and Mark for providing a space to indulge our hobby and for some, profession. I feel very lucky to be able to enjoy learning and sharing. In no way do I want to come across as bragging or ungrateful. I have learned a lot over the past 20 months or so. I hope I can give back half as much as I have gained. 

That said this post is dedicated to @rossjackson01 whom I have seen recently state to the effect that he could not work on a mexhanical chronograph for at least 2 more years. I hope that he gets an oppurtunity sooner than that and there are still bargains out there if cost is a determing factor.

I won't say how much I paid as you would not believe me,  but this could be one of the best 404 club entrants ever, at least for me.

One of the factors that led to this was a discussion with the seller that reiterated other similar discussions here and elsewhere to the fact that many independent watchmakers don't work on chronos due to cost and difficulty in finding parts. Add in Swatch owing eta/valjoux and restricting access to parts and so it is tough getting one serviced. Add in that Venus is a precursor to the Valjoux 7730 and ultimately 7750 and others, parts and service can be difficult to obtain unless we can maintain the right of servicing or DIY.

Anyhow, here it is cleaned up case and new crystal with a new mainspring on the way (that is part of the story sourcing that part). I usually don't like to post things before I get them in the mail or finish the work to not jinx myself!

I will post pictures as I get into the repair and cleaning, and hopefully no other parts will need replacement! I put a neat little strap on. Is about 35.7mm but is larger on the wrist with the pushers probably closer to 38mm. 44mm lug to lug and 18mm strap width. Works very well on my small wrist.

 

Edited August 5, 2024 by Razz
Typo

[rehajm]

Very nice- I’m a little surprised there aren’t more stories where the owner gives up and sells for a song. 

[Razz]

Pictures of the movement. Not perfect and the case screws and clamps have some rust, but it appears everything it there and working properly (sans the mainspring).

[Razz]

Update: got the movement disassembled and sure enough the MS was broken. Ordering a new one took a bit as it calls for a GR4568 which is 420mm long. As Venus is now Valjoux and Valjoux is Eta, which is Swatch, that mainspring is a restricted item. No worries found another one that is similar except the length is 400mm. 

Had some trouble with the hairspring as the BE was 5.0 and got it down to 0.2. The Amp is not good so and the rate somewhat varies over time and position. Not sure if it is all hairspring, balance jewels or other train pivots etc. But making progress and likely put the chrono works back on and get it going, then do another disassembly to reclean and relubricate the watch works.

[Razz]

Spent a couple of hours last night and this morning reassembling the Wittnauer. Need to fine tune the minute recorder hand slightly off. But everything rums and the hands all are operational. Slight problems with the haispring but the chrono works perfectly. I think it is an issue with the terminal curve on the hairspring that is causing issues with the rate, Amp and BE for the most part.

[rehajm]

How’s the amplitude when the chrono is engaged? 

[Razz]

8 minutes ago, rehajm said:

How’s the amplitude when the chrono is engaged? 

Great question. It drops 6 degrees, but sucks to begin with. I.am seriously wondering if the lift angle is 42 because the Venus 178 is 48 degrees and the Valjoux 7730 (manual wind) is 52. Before adding the chrono and driving wheel I was only getting around 235 to 240 at 42 degrees with a new mainspring, but reading 275 or 280 at 52...

[Klassiker]

3 hours ago, Razz said:

I.am seriously wondering if the lift angle is 42

You could measure it yourself, to satisfy you curiosity.

[Razz]

I have thought about it. 

[AndyGSi]

Have a look at WatchGuy below and his 188 services.

In some he makes comment about low amplitude due to 42 deg lift angle.

https://watchguy.co.uk/cgi-bin/library?action=show_brand&brand=Breitling&calibre=Venus 188&offset=0

[rehajm]

I

4 hours ago, Klassiker said:

You could measure it yourself, to satisfy you curiosity.

I tried to measure my Venus 170 using the 180 degree method but under-wound the tg reading would flutter too much to hazard a guess at the lift angle. After a couple of deep dives for faults I gave up. It does keep time despite the poor performance. Perhaps it affects the  178 as well?

[Razz]

8 hours ago, AndyGSi said:

Have a look at WatchGuy below and his 188 services.

In some he makes comment about low amplitude due to 42 deg lift angle.

https://watchguy.co.uk/cgi-bin/library?action=show_brand&brand=Breitling&calibre=Venus 188&offset=0

Thanks for the.link! Very good info and I can see on at least.2 hairspring approx where and shape of the terminal curve

 This will need to be fixed first to get the rate, amplitude and BE to where we can start adjusting the regulator pins (If necessary).

 

[Razz]

Some fiddling tonight was able to get somewhat of a terminal curve going which helped the spacing of the spring while breathing. Got the rate down to manageable. Gain 35 degrees of amplitude just by that tweak alone. Also helped on the beat error. Taking it slow will let this cycle through a wind or two before attempting anything more on the hairspring adjustment.