Tuesday, 11 June 2013

Fixing the Calendar Mechanism On A Comete Diver's Watch

Earlier this year, during my usual daily perusal of eBay's used watches, I found this cheap wind-up watch and couldn't resist.

Looks great, it's reliable, and it's got a diver's bezel! There were two good reasons for it's low price tag though. 1: Condition - "well used" would be a generous euphemism for it's state. The following photo of the case back (hopefully) shows some of the deep scratches and dents that the watch has suffer when trying to be opened by and inept former owner.

2: The Calendar Mechanism: Didn't work, hence the reason for this post.
To start, the back is cracked open to show a nice, clean, simple and serviceable movement.

Out of the case with the dial removed:

And now to start the tear-down.

After the usual tear down, I found no problems so I flipped the movement over and started to investigate the calendar wheel.

I wound the crown forward and back, and now the calendar mechanism appeared to run smoothly. In watches that don't have a quickset function (usually one of the three crown positions that causes the clutch wheel to engage the calendar wheel - either directly or indirectly) there is a skip function between 9pm and 12 midnight where you wind forward and back to skip the calendar wheel forward. Watches that have a calendar complication, but no quick wheel advancement method (other than winding!) are quite rare.

To investigate why the wheel wasn't functioning whilst cased, but was when the movement was uncased, I wound the crown back to see exactly how the calendar wheel works.

As the calendar wheel rotated anti-clockwise (reversing the watch's time) the calendar wheel tooth recessed into the calendar wheel and a spring protruded from the opposite side of the wheel.

The calendar wheel tooth then slid over the date wheel index tooth.

And popped out, free to engage the calendar index tooth from the other side, to advance the date wheel when the crown was then wound forward.

So where's the problem? Well, the plate that holds down the calendar wheel tooth (which is actually a tooth on the end of a spring) is quite loose. It sort-of-but-not-quite floats on top of the tooth-spring.

I found that when even a little pressure is applied to this plate, the calendar tooth became jammed and did not have sufficient clearance to move. This then is the likely cause of the date mechanism malfunctioning. The remedy should simply be a more careful positioning of the dial which sits directly above the calendar wheel. The dial is not in perfect condition, so a little "persuasion" may be needed to generate the required clearance between the dial and the calendar wheel plate to prevent pressure on the calendar wheel tooth.

Monday, 10 June 2013

A Massive Bag Of Watch Parts!

Last week, whilst I was in my Jeweller/Watchmaker Supplies store acquiring a buffing rouge, one of the guys said "wait here David, I've got something you may be interested in". I indulged the mystery and patiently waited. When he returned he dumped a rather substantial bag of metal on the counter and said "25 a kilo".

Here's half of what he placed on the counter (I'd sorted half already when I took the pic):

And inside the bag:

The bag weighted 3 kilograms, and was the densest, most assorted jumble of watch parts I've ever seen. Every conceivable part, for wrist and pocket watches can be found. The vast, vast majority of the parts are still in useable condition - including the balance staffs. I thought with the haphazard packaging, weight and constant contact between parts would render the more delicate items unusable, but that is not the case.
I'm told these came from an old store down south (Sydney/Melbourne) and these parts have been collecting dust for quite some time. The problem for my wholesaler is that the time expense of sorting the parts would certainly exceed any possible benefit from their sale.
Now, for a borderline obsessive-compulsive individual such as myself, the 2-3 weeks needed to sit down and sort through the thousands/ maybe tens-of-thousands of tiny parts isn't much of an issue.

The remaining half:

 In my view, biggest benefit from this bag is the multitude of crowns and stems I now have. I have about 1 kilogram of stems & crowns which can now be put to work. Even if I cannot find an acceptable part within this substantial haul, I should be able to machine, file or cut parts to fit where needed.

Here's my current storage solution. It's a small case with internal dividers made from plastic rulers with tiny paper packets holding various different bits sorted according to function.

Unfortunately, this small case won't be housing the stems, crowns, balance wheels, plates, bridges and wheels (too numerous).