Problem with Big Pilot Perpetual Calendar Moon Phase

I have recently purchased a Big Pilot perpetual calendar IW503801. The watch works fine except the moon phase is about 1-2 days behind. According to moongiant.com, March 12th, 2017 is full moon day. But the moon phase on my watch is not centered. And it was not centered on March 13th, 2017 either. It was center on March 14th, 2017. So I decided to contact IWC to see if there is a problem on my watch. After 2 weeks of waiting, and I finally got an answer today by email from the IWC concierge team:

Thank you for your interest in IWC Schaffhausen; we appreciate your patience.
Our watchmakers have advised that the moon phase display on your Big Pilot's Watch Perpetual Calendar is within tolerance. They have informed us that due to gearing and printing specifications, it cannot be perfectly aligned.
We remain at your disposal for any further information you may require.
Kind regards,

I was shocked to get such reply from IWC, I thought these watches are very precise. So is this really normal? Please help!

Thanks!!

Hi great watch, and NO that's not normal in my opinion. Just guessing but to my eye it's indeed 1-2 days off which that has nothing to do with 'tolerance' in parts or print.
Just go back to the IWC dealer or an IWC Boutique and have it fixed. It's a shame but it can happen...

Kind regards,

Bob

I wouldn't accept that response.

Wouldn't accept either.

Please take into account that full moon can happen during the day and must not necessarily happen at midnight. Your Perpetual Calendar does not move the moon phase display synchroneous to the time. The moon phase display is moved at midnight as part of the calendar change. As a consequence your moon phase display may be slightly off center (left to 12 o clock) at the date of the full moon, but should move to slightly off center (right to 12 o'clock)at the next day. When this happens then the Perpetual Calendar is ok.
If the moon phase display is off center to the left or the right at the date of full moon and the following date then it should be synchronised by a watch maker.
This info can be found in the archives.

Gentlemen:

A similar discussion came up sixteen years ago on another watch forum and here is what I replied:

I’m not a techie with mathametical or theoretic answers to the specific issues you raised. I’d like, however, to bring to your attention an interesting observation I noticed on all IWC moonphase discs.

As you probably are aware, moonphase discs (most often blue in background) have two “gilt” solid round circles opposite each other which, when advancing daily by one tooth, indicate the phase of the moon through the aperture on the dial. If you look very closely (preferably with a loupe) at the position of the moon on certain days, e.g. NEW or FULL, on an IWC DaVinci you will find that every other cycle is slightly off. So, when you check your timepiece this Saturday, August 4, 2001 which happens to be a FULL moon the moonphase showing on the watch may or may not be dead center depending which half of the complete 360 degree cycle the disc is in.

This is no oversight from their factory watchmaker but due to the fact, as you explained, the actual moon cycles are calculated by 29 days and leftover fractions. It is, therefore, not possible to produce a tooth wheel with absolute precision for each and every month throughout the year. With the IWC disc the moon phase automatically adjusts every “other” month for precise viewing.

Unless your eyes are like a hawk and you’re a stickler for extreme precision, chances are you would not notice any of the above mentioned characteristics I described. I’m only posting this little tidbit for the record if any IWC enthusiast should raise this problem now or in the future.

Regards,
Jack Freedman

P.S. I just noticed after posting that the moonphase shown in the photos is off for the given dates so in fact it should be adjusted. My previous reply was for those who complained that on the correct date the moonphase is very slightly off.

I don't own an IWC moonphase, but I do own a Patek moonphase and have observed exactly what you are saying here. :)

Congratulations INTER101T, it's such a beautiful watch.

Out of interest did you get back in touch with IWC?
Best regards,
Jonathan

I have gotten a response from IWC after I told them that their reply was unacceptable. Below is what they said:

Thank you for your interest in IWC Schaffhausen.
The technical supervisor at our facility in Fort Worth, Texas has requested that you send your timepiece to our facility for review.
Please see the attached packaging and shipping instructions as well as a request for service form for you to include with your timepiece. Be sure to include the original warranty card for service consideration under warranty.
Address the package ATTN: S. Campeau, he is the technical supervisor who will personally review your timepiece.
We remain at your disposal for any further information you may require.
Kind regards from Schaffhausen,

I like to have my watches to be fixed or adjusted by watchmaker as infrequent as possible since sometimes they might actually mess more things up as I experienced in the past. Interestingly, the moon phase seems to be correct when it came to the new moon in March 2017, which falls on March 27 and 28. Please picture below.

April 2017 full moon will happens on April 11, 2017. I will wait and see if this month moon phase is correct.

Dunno how this goes in SH but I used to have an El Primero Chronomaster Chronometer and after it went back to the factory for a warranty repair I got it back some 4-5 times every occasion worse than before. They messed up everything possible - hands and dial scratched, daily rates worse and worse, etc. etc... Sold my El Primero some 10 years ago and never looked back.