Christmas is past and finally finished an amateur vintage style watch build

Thanks Al for the pendant tube number and confirming the crown number (Al has been advising me👍 so knows what I am working towards). I will take your note as a "proceed with caution" as looking at it, there is very little room to remove this. I hope instead that the crown is wrong. Here is a picture:


It is a 0.9 mm thread and the outer diameter of the threaded part shown fits inside the pendant tube as it is just under 1.4 mm. The pendant is a "non screw down" type with OD of 2 mm and ID of 1.4 mm. The problem is the flange in the crown which means it only goes on a mil or so and the seal diameter is made to suit that so hopelessly large. I think this is some type of screw down crown for a larger diameter pendant.

I have a generic divers style, double O ring, crown coming so can use that until I discover what the problem is. Anyway, I have two such Omega crowns going cheap!

Regards, Chris

Order from Cousins arrived and rebuilt movement. Looks much nicer, hardly show standard but perfectly acceptable. Seized dial screw was rusted out and I know the dial fits👍

From the dial side. There is a date quickset which works between about 9 pm and midnight. Neat date assembly which comes off with two screws (will need to come off again).

From the working side.

Full wind FH test straight after build and it needs a little adjustment. This was the base movement without centre seconds pinion and date assembly which are costing me 20-30 degrees so, hardly my best movement. Ah well, should be mid 200s when complete and I reduce the beat error.

There is a bigger problem as the endshake on some of the train is too tight which is also costing amplitude. Have decided that my measure/press/measure technique is too slow so, am looking at one of these. The right tool for adjusting jewels to correct endshake. This is just a picture from the web but looks like one of Al's images. The micrometer allows small movements of the jewel through the plate to easily (I hope) adjust endshake.

Next weekend will make a case pressure test and sort this endshake. Hands and other parts on the way tomorrow so, looking good for Christmas.

Cheers, Chris.

Interesting shape for the spring of the centre seconds pinion, curving around the third wheel. Arrived with the spring force far too large and needed relieving. I'm doing this by letting the movement down with spring attached and then loosening the screw so the spring is not pressing down on the pinion. If the pinion turns for about half a revolution, I consider it OK but, I can't find any official method for this. Probably a bit too technical for my posts....

You sure you are an amateur? 😀

The spring does not do any more than stop the second hand "fluttering", so the lightest pressure that you can set up is what you want. It would be interesting to know what method Al uses for setting these up 👍

Yes. Let's hope Al notices this as it is similar to a 56x as well. I don't have a spring balance that goes down to these sort of values so, have been doing this as a working method. Anyway, I don't have a required value for the spring force.

You're right John that the compressive force required is very low in order not to hurt the amplitude greatly. The spring I received was bag packed only and I think it may have been deformed in transit as it was far too strong and cut a lot off the amplitude when mounted. I don't have hands yet so can't check any fluttering but my other movements with this method move smoothly.

Am expecting to hear there is a special watchmaker tool for this, only made by one Swiss company from depleted Uranium with a price tag to match. Let's hope it's Horia as I now have an order open with them😉

Cheers, Chris

Firstly, thanks to Al for another comprehensive explanation.

So, pressure test. I'm using a wet tester but someone like Al would use a dry tester. Bit expensive for me. One problem with these is they pressurise the inside of the case and can "blow the bloody crystal off" (paraphrasing Michael Caine). This is the opposite of what happens when you use the watch in water where the pressure is greater on the outside of the watch than the inside so, the crystal is being forced on. There are a couple of ISO standards for these tests but, this will work for me.

The other problem is that it's a pressure vessel and these make me nervous. If they fail, expect to see shards of plastic everywhere. So, quick stress analysis of the plastic wall of my tester:

Cylinder radius = 1.5"
Wall thickness = 0.2"
Max pressure = 180 psi

Hoop stress in the wall is p.r/t = 1350 psi. Allowable for good plastic is about 5000 psi so, Safety factor (or Reserve Factor, RF) is 5000/1350 = 3.70. Even with a significant scratch giving a Stress Concentration of about 2, it still has an RF of 1.85. No problem for me.

Anyway, I'm only working here to 60m with an overpressure of 25% so about 110 psi. (Atmospheric pressure at sea level is 14.7 psi and that increases another 14.7 psi for every 10m of depth).

The crown is not screw in and I'm not willing to risk the movement for a first test so hold the stem with a piece of compressed pith wood. As the pendant internal diameter is 0.055", it only needs to resist a force of 0.25 lb.

Pressure up with the watch in the air pocket and wait so that the pressure in the watch equalises to 110 psi.


Plunge the watch in the water and reduce pressure while looking for bubbles escaping indicating a leak. Here, the watch is still at 110 psi and the water at 15 psi. No leaks so, all good.


{Edit, after Al's comment below: I wrote this as if the watch does leak so, the pressure builds up in the watch. If it does not leak, then the internal pressure stays constant at one atmosphere, 14.7 psi and there are no bubbles}

Picture after test and it lives up to its billing. Note gratuitous water droplets.😁


Bit more later, coming together nicely now.

Cheers, Chris.

Out of interest, this pressure tester calculation is similar to an aircraft fuselage. Atmospheric pressures are:

At sea level: 14.7 psi
At 8000 ft: 12.2 psi
At 36000 ft: 3.3 psi

Big commercial jets fly at about 36000 ft. This avoids most of the gusts of wind and turbulence. It gives a smoother ride but the real reason for avoiding these gusts is not for you, the passenger, but to reduce the wing fatigue loading. This gives a lighter structure so, more passengers and more money for the airline (or cheaper fares as it's a trade off).

But, the air is far too thin at 36000 ft so, to avoid asphyxiating the passengers (tends to reduce repeat customers), we keep the fuselage internal pressure at about 8000 ft. This is why you feel dry and lethargic after a long flight. You're not used to living at 8000 ft unless you're from Mexico City.

Anyway, that means the fuselage has an internal pressure of 12.2-3.3=8.9 psi. We design it to withstand at least twice that for safety but, the cycling of pressure every flight also gives us a fatigue problem due to the hoop stress. A good fatigue allowable for the type of Aluminium used for fuselage skins is 20000 psi when the aircraft is designed for about 30000 flights.

So, hoop stress = pressure*radius/(skin thickness)

Fuselage radius is about 110” for a widebody jet.

Solving the equation gives a skin thickness away from local cut-outs or other special areas = 0.050” (the closest standard gauge thickness).

That's the skin thickness we use, 0.050" or 1.27 mm. Did anyone realise it was so little?

We could keep the fuselage at sea level pressure for a more comfortable flight but, that would need a 0.072" thick skin and the weight increase again reduces the number of passengers/profit margins.

Chris.

I didn't realise the skin thickness was so small. No wonder MH17 just disintegrated . . .

MH17 was just terrible John. These missiles explode away from the aircraft and pepper then with shrapnel. No-one stood any chance at all. But, excluding acts of war, a nice safe place to be.

Back to watches. After more playing with endshake and fine tuning, I got the movement to this in FH with all mounted except the auto winder, and am very happy with it. 265 degrees plus at full wind in all six positions and a maximum of nearly 300 degrees is very good. These movements really are very robust.


Note that my new Horia tool (good for endshake adjustment) is with Spanish Customs who seem to be trying to rebalance the economy with my import duty. I think the latest number is 40+% which has come as a bit of a shock. Never send anything to Spain with this French description "Outillages Horloger".

Dial fitted and cased for the moment. No bezel or hands yet but, on the way (who knows what import duty level they will dream up?). Fits beautifully. Terrible light today for photos as it is tipping down!


With two bigger sisters. The 120 is running as it was on my wrist with it's new rubber strap, seems strange but very comfortable. Will get some strange looks at work when I wear this tiny thing for a few days to try it out.


Stem trimmed and auto mechanism fitted so, all done except for hands and bezel. You can just see one of the case clamps right next to the balance. Terrible place for it but there is nowhere else. Obviously scrap spring bar which stays on until the final pressure test.


Cheers, Chris

Thanks Al, my explanation was a bit confusing there. I will reword it later. Yes, good suggestion, I will run the final test above the water line first. No crystal pop outs yet but, have only tested a few watches... It is a Calypso as well. I suspect your crystal pop outs were all non dive watches?

I was going to say that the case seals are generic as I couldn't get an Omega one. They came in a pack of three so, I took the opportunity to try one dry as a test. As expected, it leaked and confirmed to me that lubricating the seal each time is essential.

By the way, terrifying pictures. Was that a deep test? 300m plus? That wet tester you are using looks designed for very high pressures so, I assume so.

Cheers. Chris

So, after an age with Customs, for reasons only known to themselves, I received the new bezel and hands. Fitted last week and given to my wife Saturday evening who was thrilled, especially with the colour and the effort involved in building it for her.

This is the first watch she has ever owned with a date so there was a bit of an explanation how the quick set worked. I had not thought of that 🙄 but, I suppose most women's watches used to be too small (not true today). And the first ever waterproof watch but she's not sure about taking it swimming. Ah well...

So, it is a (franken) 566.0024 as Spiki thought. Runs like a train (in UK that means late and slowly but not here😉) with great amplitude, low beat error and nearly 50 hour reserve. Thanks to Al for oiling advice and many other things. Very pleased and a most interesting project but am going to lay off these tiny movements for a while.

Bezel colour is very close to the dial in the metal but catches the light differently. It is quite stunning in hand.


All spare links removed from new bracelet and only one clasp adjustment point left. Just fits.


And with two big sisters.

Cheers, Chris

Excellent Chris!!
Really nice and informative thread again with an amazing result. Beautiful watch!
Wish lucky Mrs. N to wear it in good health.