Regulating IWC 79320 | Beat Error dial up or down different | Flieger Chronograph 3777

[AlexanderB]

Hi,

one of my favorite watches is my IWC Flieger Chronograph (Ref 3777).

The only thing that annoyed me was, that it was almost 3s late every day. 15s or more in a week! 

I know, this is complaining on the highest possible level. But still. If she would go 15s fast a week. Fine. But not late.

My Weishi Timegrapher 1900 showed it pretty clear. After quite some experience with movements I dared to open it! No way to take the movement out, just opening it. Wow, what a nice movement!

But regulating the balance proved to be a challenge:

There is a little screw (going from the left to the right) which is used for fine regulation. The only problem: the screw is obscured by the case. And the stud is extremely smooth moving. The first thing I did was bringing the balance out of center while pushing just a little bit too hard. I was totally relaxed, because it was easy to bring it back in the right position with the Timegrapher.

What is good about the 1900 model is that the two lines (tick and tack) are in different colors. When you push too hard the yellow line is above the green one (or vice versa) and you know, you went too far. The beat error itself does not change (e.g. turning negative). Very nice and helpful feature.

It took me quite a while to get everything in perfect condition. With dial down I had to regulate her 2s fast. 

To make a long story short: in the morning she is spot on and in the evening she is 1s late (again!). But with crown down she is running 1s fast in 7h during the night. Spot on next morning!

BUT: Here is my question: The beat error is 0ms dial down but 3ms dial up. I have absolutely no explanation for that. I thought that the beat error should be the same no matter what position the watch is in. This was also the case before I regulated her.

I am looking forward to hear your explanation!

Thank you and Cheers

Alexander

 

 

Edited June 8, 2016 by AlexanderB

[matabog]

3ms between positions is huge! Are you sure it is not only 0.3ms? because that would be ok.

Edited June 8, 2016 by matabog

[AlexanderB]

I'm sorry. You are right, of course. 0.3ms! 

[matabog]

the you don't need to worry (IMHO)

[AlexanderB]

Thank you. I am not really worried. But I'd like to understand this phenomena. From my understanding there should not be a difference at all. I would expect a difference with crown down or up opposed to dial up/down. But not with dial up / dial down.

Just curious.

Cheers Alexander

Edited June 8, 2016 by AlexanderB

[matabog]

It is not perfect. It is an oscillating system. It has a positional beat error the same way it has the gain positional error (or delta).

The easiest causes to understand (at least for me) are the end-shakes in the escapement.

Edited June 8, 2016 by matabog

[jdm]

Just now, matabog said:

It is not perfect. It is an oscillating system. It has a positional beat error the same way it has the gain positional error (or delta).

Not in my experience of having regulated many dozen of watches. Dial up / down beat error typically varies of say 0.1, 0.2 mS, most times not at all.

[matabog]

I'm a hobyist  I only have experience in breaking and loosing things. 

Nonetheless:

 

[jdm]

From what I understand the video above mentioned a kinked hairspring, yet the beat error variation stayed pretty small, well under 1 mS. 

3 ms BE variation is not acceptable on a healthy, quality movement.

[matabog]

@jdm he ment 0.3

[jdm]

12 minutes ago, matabog said:

@jdm he ment 0.3

Oh sorry I did't saw that. All good then.

[AlexanderB]

Thank you very much for your contributions @matabog and @jdm.

Especially for the video. First of all this value seems to be normal. For hobbyists it is always good to have some values to rely on, to get a feeling for what is possible and what not.

I probably should bear in mind that the beat error of 0.3ms is 3/10,000 of a second, and I wonder if my 250 EUR timegrapher is actually able to really measure the difference properly. It might be the case since I don't get differences when going to the positions back and forth.

After two days I am extremely happy with my work on my IWC. It still loses a second during the day and gains a second during the 7-8h at night (9 up).

Again thank you, especially for the video. Learned some more!

Cheers Alexander