What would you suggest would be a reasonable daily accuracy tolerance (+/-)for a vintage 1957 Mark XI? The piece has just been restored and serviced at IWC Schaffhausen after a couple decades of not working.
What would you suggest would be a reasonable daily accuracy tolerance (+/-)for a vintage 1957 Mark XI? The piece has just been restored and serviced at IWC Schaffhausen after a couple decades of not working.
Wow. I am sure it's a wonderful watch.
I am not going to fathom a guess or express what I would expect. However, I would make sure I give it several weeks of relatively regular wear or running since the restore before I pass judgement.
No need to guess. If those tolerances were acceptable to the RAF, who were actually using the watch for a very important job, they should be acceptable to us.

Yep, I have to agree, Clesydra! Can't help being obsessive about this watch though.
There is nothing wrong with being OCD, especially when centered on the Mark 11.
Is it known to be that different resting positions for this watch affect the plus/minus readings? I notice that when I rest with crown down it gains and loses with crown up. Is this resting position change specific to a watch or will, for example, all manual watches gain if rested on their side crown down?
Hi Blubarb,
I understand your passion completely.
Every IWC Mk 11 was built and granted to be a chronometer, although the definition of being a chronometer changed over the years, resulting in a far less demanding effort of the timepiece involved.
I realise that my answer to you might be considered by you as silly.
A Mk 11 in my collection does not have to run + or - 2 seconds in a day. It had to do so, 65 years ago, when these were on service.
Given wear and tear for more than half a century in a drawer without any service, I would be quite happy to see the Mk 11 tick anyhow. However, the reality is that these Mk 11 watches, if restored properly, still can function as a chronometer!
Kind regards,
Adrian,
(alwaysiwc).
Adrian, I completely agree with you
I am really more than impressed, to date not more than +5 in any single 24 hour period! The party is still going!