View Full Version : Mechanical WW Hairspring needed

Dave B
10-20-2009, 11:08 AM
I usually work on clocks, but told a friend of mine tht I would tackle his pocket watch for him. It is a 16s, 8 day Swiss mov't, labeled "Comfort" on the dial. He accidentally dropped it into his swimming pool. It did not pass the water test. I was able to get all the rust and crud off of everything except the balance spring. So I need to replace that. If possinble, I would like to find one that is already mounted on the collet, but if need be, I suppose I can remove the pin, and pin a new one to his old collet. Does anyone know of a supply house, where I can obtain one, provided I send them dimensions?

I also noted, when I disassembled it, that one of the balance bridge screws is missing. The previous repair person had glued that side of the bridge to the plate. A good cleaning in Acetone, followed by the usual ultrasonic baths got rid of the glue, but I would like to locate a screw, to reassemble the watch properly.

10-20-2009, 11:36 AM
Good Morning Dave,
Is this a Hebdomas? I may have some screws.

The balance will need to be in hand to match a hairspring to the balance weight, and then vibrated. It is usually a matter of trying several springs out preliminarily to see if they can be matched to the balance before vibrating and cutting, as once you cut the spring, then you are committed.

If you are experienced at vibrating hairsprings, then you may be able to get the thickness of the original spring, and have one sent to you that is close, and then complete the vibrating process. This would involve, though, re-attaching the original collet and stud, and you would have to have a good quality micrometer.

I do have a selection of hairsprings, and if you like you can contact me offline,

Dave B
10-20-2009, 03:38 PM
"Is this a Hebdomas? I may have some screws."

The only brand marking, other than "The Comfort" Is "Wyss Freres" on the intermediate plate, under the balance wheel, which I take to mean Wyss Brothers. It is a 7 Jewel, 8 day movement, of the type wherein the mainspring is contained within a going barrel that comprises the upper plate. The dial is cut away, and retained at the bottom by a lip on the underside of the balance bridge and and angled screw at approxivately 11:55, next to the stem.

I own several good micrometers, and can easily measure the spring for strength, width, and length. Alternatively, I can compute the length, knowing it is an even spiral, and the number of turns and the spacing spacing between turns at each end.

As to vibrating the spring myself, while I understand the theory, I have never actually done it, and I suspect that without some close supervision, I'd mess it up.

10-20-2009, 04:13 PM
Hi Dave,
Here is a link to an open escapement 'hebdomas' style watch


Vibrating a spring takes quite an amount of practice, and patience. It is a bit easier if the spring is flat and does not have an over-coil. But still, not for the faint of heart.

Anyway, I probably do have a spring that you could use, if you wanted to try yourself. If you need it to be vibrated, you could contact me offline.

If it is the type of watch at the link above, I probably have the screw also,
Hope this helps,

Dave B
10-20-2009, 11:38 PM
Joel - Thanks for the link. I believe that is what I am dealing with. I am attaching some photos, so you can see what I am up against. The spare balance spring is the closest I have to a match, but I suspect it will make the watch run super fast. I forgot to take a photo of the collet, with what is left of the spring in it. Suffice it to say, it is just as nasty, and removing the pin and rusted bit of remaining spring might be a serious challenge.

Incidentally, in case you wonder, I did not make the two scratches in the barrell washer. I think I will be able to buff them out, with some judicious polishing. I know that is probably not what my friend expects, but it just seems right, while I am messing about with it.

10-21-2009, 10:34 AM
Yep, you have a classic Hebdomas.

Hopefully the hair spring you have will work. Even if it is to fast (depending on the rate), this balance does have removable balance screws, so you could add some timing washers.

Notice that the balance is not split, and the watch really only has 6 jewels (the roller jewel is usually steel in these), so don't expect stellar performance. But, they are a curious watch (more akin to a small clock).

Driving the pin out of the collet can be challenging, but it should not have bonded if it is brass (as both the collet and the pin should be).

If you include a picture of the exact screw you need and were it goes, I'll send it to you.
These watches are 'interesting' to work on,
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OH, by the way, the easiest way to work on the hairspring collet (both pinning and removing) is to use a small size smoothing broach by running the collet down on the broach and sticking it in something on your bench so it is upright. That way, the collet stays put as you are trying to remove it (and pin it).

That has worked best for me, anyway,
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I thought that I had an image of a collet and hairspring on a broach, but can't find it. Here are some shots of the vibrating process and overcoil forming

Dave B
10-21-2009, 12:44 PM
Thanks. I had planned to use a broach to hold the collet. KNowing my luck, I am also going to wrap a piece of tape around the end of the broach, beyond the collet, so when I screw up, it can't go flying! :o

I couldn't get a decent photograph of the screw, so here is a "quick and dirty" dimensioned drawing.

10-26-2009, 10:26 AM
Hi Dave,
I have not had a chance to look yet. I will check soon,

Go ahead and email me at jtrenalone@timepieceshoppe.com so I can get your address etc,