IWC's seven day design

Greetings,

When IWC announced its revolutionary Calibre 5000 –its first in-house automatic in years-- in 2000, the movement contained several special features, including a seven-day power reserve. Some people were intrigued, since the watch would have a week's “autonomy”, and for example it would be “set to go” if perhaps just worn on weekends. Others scoffed at the notion of an automatic with a seven-day power reserve. They understood why a lengthy reserve would be useful on a manual watch, but not on an automatic which should stay fully wound when worn.

IWC also did something unusual to create the lengthy autonomy: it used a huge barrel, specially coated, and had an enormously long mainspring inside. It was a simple solution, in a sense, since the long spring would take longer to unwind. This was unlike what some other watch manufacture's then did –such as using two smaller barrels, in one watch, that would run in tandem. Kurt Klaus told me 10 years ago that IWC's design was simpler and, therefore, there was less to go wrong.

But –did IWC make a mistake? The huge barrel needed for the lengthy mainspring takes up a lot of space, and requires a large movement (and correspondingly a very large watch). Some have argued that the pressure from such a large mainspring as it unwinds creates greater isochronism error –that is, accuracy can be affected, and even a few seconds can make a difference. Or do we really need 7 days' power reserve? For normal use, isn't 36 or 78, or even 72 hours enough?

Still, the feature is useful and distinctive. Perhaps IWC not only didn't make a mistake but also accomplished something important.

What are your thoughts?

Regards,
Michael

I love the 7days movement in my 5002, because it's not easy for me to wear this with suit in weekdays. Also, winding the watch on the 5th day is a pure pleasure... so the longer it takes to get it fully winded just prolong my pleasure moment.

Michael - I would have to say that the 7-day power reserve is quite practical and innovative. The ability to wear a Portuguese, or Pilot, etc just 1 or 2 days a week to keep it running is great. I always have thought about the "chicken or the egg" paradox - is the case big because of the power reserve? Or did IWC correctly design a large, stylish case that made it possible to "go big" with the power reserve?

Below is a link to a movie I shot of another Forum member's Cal. 5000 during a presentation on the Cal. 5000 power reserve by none other than Kurt Klaus....

homepage.mac.com/rsheridan/.Public/Larrys_5000.mov

Well its clear that for everyday use an AUTO 7days PWR is not necessary...BUT...what about if you rotate it your IWC with other pieces?...Now...makes sense!

I do...and I see really useful to have a full week when taking again one of my favorite watches and see it´s "ready to go"!

I also see that the 7Days IWC movement very reliable and really accurate compared with other long power reserve pieces I own.

Many time is not just coming with something new that the others are not offering...but offering a new perspective to the market. And IWC did it great!

Cheers!

I think the 7 day movement is a horlogical achievement, and have found no better explanation of its uniqueness than your article about Kurt Klaus-

people.timezone.com/mfriedberg/articles/einstein_from_schaffhausen.html

My other mechanical watch has a power reserve of 42 hours and I inevitably have to wind it by hand and set it if I don't wear it for a couple of days. So I find the increased autonomy of the 7 day movement extremely practical as well. Perhaps the large movement did compel a large watch, but I personally love the classically elegant and superbly legible result it produced-

My 2 week old 5001-07 has also kept perfect time so far!

Winding automatic movement can make no slack, maintain accuracy, a good design.

I am very happy with the 7 day power reserve in my BP and Portuguese Automatic. Having more than one watch means that a long power reserve is a big plus. I agree that if you own only one watch, it's less of an advantage.

Kind regards,

Clemens

The seven-day power reserve is a godsend, in my opinion. If I don't want to wear my 5004 for a few days, I never have to worry about it winding down -- and having to reset the time. None of my other watches -- including other IWC and Breitling models -- has this feature, and they're always winding down if I don't remember to keep them wound. How about a big YEAH! for this wonderful feature.

Steve

I think that a longer power reserve has practical advantages when you wear different watches in a kind of rotation. Certainly with a perpetual calendar you can feel the advantage at not needing to set that calendar: that may be easy, but I don't know because I never did until now. However, more useful to me is the power reserve indicator. That would be certainly more useful with a short power reserve, but after a while you really don't know whether the watch would survive the night, no matter long or short power reserve. This is certailnly true if you are not such an active man: sitting all day checking e-mail and so doesn't really rock the watch.

So, well done IWC. What will the next innovation be?

Kind regards,
Paul

I also think the 7-day power reserve is a great achievement. My PPC ran down only once since since purchased in December and I did that to see if it would become more accurate. As I thought, it did not and continues to be ~12 seconds fast per day.

I'm still debating when I want to send it in??

12 seconds fast a day is a bit much, in my opinion. I believe IWC states that the watch should run no more than 4 seconds fast a day. Certainly when you still have warranty on the watch, you could send it in free and have it fixed. But the question remains if it is worth it: to go twice to the AD, to miss the watch maybe several weeks. In the end, I would do it, as a quality watch that cost a lot of money should not run that much fast.

Kind regards,
Paul

Err, not exactly. Chronometer(COSC) specifications are -4/+6 seconds per day. IWC does better because it believes a watch shouldn't run slow, so I believe their standards are 0/+8 seconds per day (a narrower range as well).

+12 still is slightly off. I personally would do the following:

a) since actual results may depend on individual use, I'd experiment with trying different resting positions at night time for the watch, and time the differences over a statistically significant time span; and

b) if it can't self correct, I'd wait until right before the end of the warranty period, and submit the watch then in order to resolve any other small issues at the same time.

Paul and MF,

thank you for your inputs. The good news is the ~ 12 seconds fast per day is constant no matter what night time resting position is used (crown up, crown down, dial up, dial down). The only positions I haven't tried are vertical ups and downs.

The other good news is that I am visiting an AD tomorrow that is about 2 hours away but the closest to me. I may have a new aqcuisition (any suggestions?) when I return but will also wear my PPC and discuss with them the adjustment of the movement.

I am more inclined to wait as MF states, mainly because I hate the idea of not wearing it for 3 - 4 months.

Thanks again, Eric

You should try all the positions anyway. I have a Big Pilot Perpetual which I had tested up in NYC (remember Bill?) . It showed about 11 seconds per day fast. The weird thing was that I had not adjusted the time since the previous daylight saving change. And to this day the watch runs to within 1 or 2 sec per day. So somehow the wrist action and winder movement is cancelling the deviations out.

I'm the proud owner of a Portuguese Chronograph, and am almost ready to acquire one more Portuguese Automatic 7 day power reserve to complement my IWC collection. However, after reading about people's comments about the IWC 7-day power reserve on several watch forums, I begin to wonder if the seemingly high inaccuracy (+7-15 seconds per day seems to be the norm, and deteriorates as it winds down) of the IWC 7-day design is worth the money. e.g., see the timekeeping poll at watchuseek:

forums.watchuseek.com/f350/7-day-movement-timekeeping-poll-331774.html

Among my collections, the Rolex GMT is the worst at -5 seconds per day, and I don't think I would want to tolerate an IWC Portuguese Automatic at anything higher than +/-5 seconds per day. After all, they have been making accurate timekeeping pieces for more than 70 years. Is the 7-day power reserve movement not designed for accuracy or am I asking too much?

This is very unusual. IWC watches are calibrated in 5 different positions to ensure acceptable deviations in accuracy.

I own a 5001 which I wear every day. Under normal use for 12 or so hours, it gains 2s to 3s. I rest it in a specific position at night in which it would gain maybe another 0.5s. Total of +3s a day on average, which I think is decent and pretty common among watches using this movement. I'd certainly have it checked out and regulated if it's gaining 15 seconds a day.

My 5001 ran +15sec fast, and that was unchanging no matter what the position., and ran like this for many moons.

Then the kind people at IWC arranged for it to be regulated in Sydney, and it came back I though more accurate, but now I realise that it changes from + to - seconds depending on the position, which it never did before.

But this allows me to place it in the appropriate position, depending on it been fast or slow, and it'll self correct. which is good.

Now.... how is the 5001 regulated? In the earlier movement it had an easily visible adjustment, but the newer movement like mine doesn't have the visible adjustment, so how is it done?

Why is my 5001 now changing pace after regulation in Sydney by IWC? I would have thought that the process of regulation wouldn't break the fact that it's adjusted in 5 positions?

I'm not the pedantic sort (not for a couple of seconds anyway) but I think you did the right thing sending it in. I believe IWC's philosophy towards timekeeping accuracy is an indicative range between 0s and +6s for every single position. Not that I would complain if my watch runs a constant -1s or +7s every day of course. I'm surprised your 5001 was able to hold a steady rate in various positions.

When all is said and done, whether it's 1s or 10s, the precision we're talking about here is still in the order of 99.99%. That's an astounding feat by any means and from any perspective, considering the type of spring-driven engineering that's realising it.

To answer the question about how the 5001 is no regulated without a regulator, it has a free-sprung balance. That is a better system but more difficult to get right. There are screws on the balance ring that are turned in or out, decreasing or increasing weight and effecting the spinning of the balance wheel. Once the right weightings are set, it is much more difficult for the rate to change, whether over time or due to shock.

There is more in the archives about tis and also you might get somewhere by Googling "free-sprung".

Thanks Micheal, does this mean that it's harder to regulate a 5001 movement? And even harder to regulate it in the 5 positions that it is suppose to be regulated in?

Harder? It requires more skill and time.

It produces better results, and has been used by Patek and Rolex for a long time. I don't know, but the Rolex manufacturing process is highly automated, and I suspect they even have machines for free-sprung regulation.

Adjustments (say to five positions) differ, as you presumably know, from regulation. I would guess tweaking the balance wheel actually produces more consistent adjustment, and in that sense would be "easier".

Micheal, it sounds very interesting, I'll love to see some photos and diagrams of how the 5001 is "adjusted in 5 positions" in the factory.

perhaps some photos of the place where it's done? and the equipment used?

I'll love a factory tour, but Australia is very far away from Schaffhausen.

for me, love to see the power reserve go up when winding it by hand :) super great feeling :)

hi all, i was looking for solar power watch because i thought i will never find a mechanical watch with longer power reserve. i asked couple of sales people, they always tell me mechanical watch is only 42-46 hours power reserve, and giving me a look which i looked stupid to them. one day in hong kong, the sales person point me to panerai and iwc(auto-wind ofcause), immediately i fall in love with the design by IWC. i like this feature very much and the best part is that i do not know what is IWC at all. Now i know, and i must share with people here, amazing. The watch its dial catch my attention just like that, no matter looking at it from which angle. Clean, easy read out, balance, handsome. I really don't care what people talk about this brand. I only know that this is the watch i want to find.

pic.twitter.com/EgnpQQJh