Clock Drift (Portofino 8 Days Hand Wound)

My brandnew IWC Portofino 8 days hand wound (ref. 5101) has a +7sec/24h clockdrift.
Is that too much?

First of all, welcome to the best IWC forum in the world and congratulations on your beautiful Portofino hand wound.

Seven seconds per day is just within specs (0 to +7 seconds/day). Often watches need some time to 'break in' and it's possible the deviation will get a bit less after a few weeks.

Talking about accuracy, 7 seconds per day (86400 seconds) still means 99.992% accuracy which is remarkable for a mechanical device of such complexity!

Enjoy your Portofino and wear it in good health!

Kind regards,

Clemens

Dear Clemens

Thank you very much for your helpful comment.
I'm really happy with my portofino and those 7 seconds per day do not bother me, i just wanted to know if there could be a problem with my watch.

i allow me to ask another question, that isnt really related to the previous question: the Portofino has a 8 days power reserve. Should i wind up the clock constantly, lets say, every 6 days, or can i wind up the watch at odd times? (f.e once after a day, the next time after 5 days, the next time after 2 days etc.). I heard that it is better to wind up the clock at regular intervals and always at the same time.. what do you think about that?

Best regards

Steven

Steven, congratulations on your new Portofino! This watch is my gateway watch to IWC, and love every bit of it!

I asked the same question some time ago (during the time when we can comment and provide feedback to all IWC articles here), and I was advised that you could wind the watch at any time due to uniqueness of the calibre. My Portfino 8 days is also close to +7sec per day and I would randomly wind it whenever I wish and the time gain is still consistent.

Regular interval winding may be more applicable to pocket watch movement such as the 98-calibres. I may be wrong here and I look forward to what some of the experts here might have to say about this.

Hi Steven and Vincent,

Interesting question! My own hand wound watches have a normal power reserve and I wind them only when I wear them. If I wear them several days in a row, I wind them when I go to bed.

Kind regards,

Clemens

The benefit of the movement in the 8 day Portofino is that it can be wound on a weekly basis, such as start the Saturday chores with a bit of finger exercise winding it up. Likewise no harm will be done by winding it every day or every three days.

You can wind as you wish, but in principle a fully-wound watch is more "accurate". As a watch unwinds the strength of the mainspring weakens, and that can cause some small "isochronism error". However the differences are relatively small until the end ofthe cycle.

The clock-drift may be different depending on whether the watch is fully wound or not. My 8-day is at +7 to +8 sec/day more a day or two after a full wound but a net loss towards the end of the 8-day power cycle compensates that gain at the beginning. After the full 8-day power cycle, it averages to less than about +4 sec/day. I contacted IWC about this through the concierge service on this site and they came back with the reply that over the 8=day cycle the movement is expected to average within +7 sec/day. I recommend winding it weekly.

Far be it from me to contradict a concierge for IWC, but with respect most are not technical watch experts. In general, averaging over a period of time is not considered the correct protocol for measuring what is commonly called "accuracy".

Imagine a watch that was fast the first day by +20 seconds, then was slow the second by -30 seconds (a 50 second spread), then was slow by -10 seconds, then was fast by +15 and on the 5th day was fast by +5 seconds. At the end of 5 days the average rate would be spot on....exactly plus or minus 0 seconds. Yet by generally accepted watchmaking standards the result is considered, in this exaggerated example, as terrible.

The name of the game is consistency. In that regard, there is a law of physics known as isochronism error. It is an immutable truth: it can be minimized with certain metals (given their low coefficient of elasticity) and using so-called Breguet spirals, and by adjustments, but it cannot be eliminated. There is a loss of consistency over time.

And, second, fine watches are carefully adjusted by a watchmaker (there are good articles on adjustments on the Net) before being sold. These adjustments cannot be done at all times in the isochronism curve, and most fine watchmakers adjust for full wind.

For the above reasons, I must respectfully disagree with the concierge and what RayInLA reports. If you can, wind a manual watch daily, and at approximately the same time. Let the watch run down when you wear it occasionally, like weekends.

Michael,

This seems like a regular topic since we had a similarm discussion not so long ago in another watch forum.

Portofino 8-days are highlighted for their ability to hold power over a longer interval than other IWC manual hand-wounds limited to 40 to 48 hours. I disagree with the need to wind it daily, especially as the calibre is regulated for the full 8-day interval.

When I raised the variations and the total time gained, this brief statement is what I received back over email from IWC (and my question apparently went to Schaffhausen for a reply):

I just received a response from our master watchmaker at our workshop.
And, here it is.

"The AVERAGE between position is 0 to 7 seconds/day, if measured in a single >>position -3s/d up to +13s/d for that caliber."

The average here refers to how the watch is kept and used (horizontal, vertical etc). I understand the difference in the accuracy of a watch vs absolute precision (i.e. keeping exactly 24 hours vs. a full cycle that returns with the same gain). Some of the day-to-day variations during the 8-day power cycle I have noticed may be related to variations in the daily activities and how the watch was left overnight. I'll try to make bit more precise measurements over the next 3 to 4 weeks.

However returning to the OP's question, 0 to +7 sec/day is what IWC considers as acceptable for the calibre 59210 movement, but note that they allow this to be as high as +13 sec/day.

Ray

RayInLA.

Sorry, I stand by what I wrote. I am aware of 8-day manual watches, including the Portofino. I am aware of different positions. Regulation cannot be done over an entire 8 day range (absent heroic fine-tuning) and isochronism error exists in all watches with long autonomy. IWC has not invented a new cure for isochronism error.

One of course need not wind any watch more than its autonomy. I suggest it is a best practice for best timekeeping. A range of up to 13 seconds/day is, by my standards, not really what one should want. And I love the Portofino 8-day and IWC.

Michael, I read your comment with interest. I have an 8 day hand wound and noticed slight a increase in time each day. IWC technical advised me today that for this watch within the first 24 hours (+7) is within range, after that (+14) each day until rewound is within range. If as you say, its not a range that one should want, i don't quite follow because quite clearly IWC have constructed a movement that does exactly that & the drift is considered normal. IWC technical further qualified that the changes in the drift will depend on usage movement etc. I gather your comments are personal (likes & dislikes) and not based on IWC standards?

Julian --I don't speak for IWC, so all my comments are personal. However, to my knowledge IWC has published its standards as 0 to 7 seconds/day. If this has been changed, I have not been informed.

While my comments are personal, that does not mean they are subjective. I was basing them on some published criteria.

When you say "IWC technical" has advised you, perhaps you can shoot me an e-mail with the person involved.

I don't think isochronism issues would/should double the error margin overnight for any decent watch, and IWC has higher standards than most. Well... from 1 to 2 maybe, but certainly not from 7 to 14. Bear in mind IWC is already limiting the power reserve to eight days from a possible nine to counter this effect, so there is no reason to accept this behaviour as normal. If it is, then I definitely wouldn't want one.

The varying torque and therefore isochronism over the length of mainsprings has been a nemesis of watch and clock makers for over 500 years. In the late 20th century the use of new metal alloys in mainsprings practically eliminated this variance, over the standard 30 to 40 hour running of watches.
The nemesis appeared conquered and over the next 50 years, as a new generation of watchmakers/designers worked their way through the industry, it was largely forgotten about by the watch manufactures.
With the trend for ever increasing power-reserves since the late 1990's, the nemesis has returned to hinder our quest for accuracy.
Multiple small barrels have been used, with varying degrees of success, by some manufactures like JLC or Panerai.
Assuming one large barrel & spring are to be used in the style of IWC, there are two principal options for the designers:
Eyeing the future, research into new alloys and spring shapes could be initiated but this would be a lengthy process with no guarantee of success.
Looking back to the past, a FUSEE could be fitted. This is a proven solution to the problem of variable spring torque and had been used in the most accurate clocks, watches and marine chronometers for many hundreds of years until alloy springs were developed.
In the 15th century, Leonardo da Vinci integrated Fusees into some designs. Although they were not related to time measuring, wouldn't it be fantastic if IWC were inspired by the association to produce a da Vinci watch with a Fusee movement?
For a couple of fantastic articles about Fusees and mainsprings, see the links below:

en.wikipedia.org/wiki/Fusee_(horology)

en.wikipedia.org/wiki/Mainspring

Leo, Thanks for this interesting information and the link. The isochronism issue seems to come up very frequently with the Portofino 8-days in various watch forums. Unfortunately, the lack of a clear statement from IWC on the acceptable day-to-day variations is hurting this line based on just a random sampling of the comments elsewhere. I understand Panerai 8-days have three barrels aimed at effectively solving this problem and a movement size that is thinner than I expected say compared to the large barrel/spring combination in IWC. There are clearly improvements to be made on the IWC 8-day hand wounds and I expect we'll see more of that in the coming years.

Ray

Leo, also from my side- very interesting scholar information...
and a total layman question- what would be the major differences on isochronism between integration of a fusee and a movement that consists of a double barrel??
cheers,
yitzhak

I have a few comments addressed to the last three posts here"

First, IWC to my knowledge is not working on any novel solution to the issue of isochronism error, nor is it planning to adopt an "old" solution like multiple barrels or fusee chains.

There are problems, too, with the solutions mentioned by Leo. Fusee chains are expensive, and I believe they are somewhat fragile. They were used 100+ years ago and virtually every company has abandoned them since (except for certain very costly homage models, like a tourbillon model by Lange and Breguet).

On multiple barrels, I asked Kurt Klaus why he didn't include that in the design of the calibre 5000. He told me he thought they were unnecessarily complex, added multiple parts and as such there was more to go wrong.

To answer Simius' question, the idea of multiple barrels is simple. If isochronism error is like a curve, the curve extends further over time. So, instead of having one barrel with a mainspring large enough for 8 days, you might have, say, four barrels each with two day's reserve, and as one winds down the next kicks in.

As you can see, multiple barrels conceptually minimize isochronism error but at a cost: more parts and more mechanisms. All movement design has variables and trade-offs. Here, the cure can be worse than the disease: isochonism error (often just a few seconds over many days) can be somewhat minimized, but at a cost --more parts and assembly aren't free-- and in theory with more costly service, too.

Finally, I said before, and I will say again more strongly, that all this talk about "clock drift" as if there is a "deficiency" that should be addressed for IWC's eight day movements is misleading. IWC has had eight day movements now for 12+ years, and they've worked fine. The original slow beat Cal. 5000 (and variations) had some isochronism error at the end of the curve, but nothing large. On the Portofino, the head of Richemont customer service in Australia checked and reported to one customer that "we have received confirmation that the tolerance of 0 to 7 seconds is for each day (1st, 2nd, 3rd….) during the power reserve". One can, I suppose, get their movement "fine-tuned" but candidly if it keeps reasonably good time to me that's all that's practically needed in any mechanical watch.

In all events, I don't think Leo's post should be construed to imply that IWC is searching for any "cure". And the "solutions" haven't been adopted consistently by the watch industry for several good reasons.

Hi Guys,
I completely concur with all the points raised in Michael's post. The 59210 is an extremely accurate movement with tighter tolerances throughout its 8 days than those achieved by many other brands' 40 hour movements.
Rather than a solution to a non-existent problem, my post was intended as an exploration of the past and possibly future watchmaking methods employed when large mainsprings are used.
My last paragraph is a bit of a watchmakers pipe dream but we can rest always hopeful.
Leo

thanks Michael and Leo on the clarifications and these interesting technical discussions, which I myself would like to see more the forum...
somehow, and again, my very personal impression, I find it bit of a disappointment that most current posts on the forum relate to the design of the modern watches, with less interest in movements function and innovations in that respect...