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Waltham 6/0 B 16j mainspring issues

Dave Haynes

Registered User
Sep 12, 2000
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I've repaired dozens of Waltham watches using the "Safety Barrel" it's always a pain to peek inside and try to drop that barrel top hook down into the spring end and get it to grip well enough to not slip. The old French made Waltham springs seemed to be softer at that end to allow some bending to accommodate hook up. I've been doing a nice old 6/0B navy model of the watch FSSC 88-W-800. I replaced the mainspring, which was broken, with a couple of new brand X alloy springs noted as same as 2226. Looked fine had just the hole at the end. After assembly the spring would slip when about half wind approached. I tried another new spring with a hand selected best looking barrel top and it still slipped, not as bad but still slipped. Finally used my last genuine Waltham spring from a batch I bought from Tom Mister at DASHTO. It isn't bent at all and still slips, but if wound slowly will go all the way to full wind. Then when tried again it will slip again. I've had this sucker apart a dozen times and figure I must be doing something wrong. I wondered if it was a short barrel arbor or something lifting a tad and them dropping back down, so I replaced the barrel arbor with a new military example and it didn't help. I'm thinking that softening the tip and really getting a tight fit is the only answer. Remarkably, Otto Frei had "Genuine alloy springs for the 6/0 watches" but they came with the T end which isn't going to work on the war time models. Ideas?
 

Dave Haynes

Registered User
Sep 12, 2000
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Have you looked to see if the hook on the barrel is worn?
Yes, that was the first thing I did. I also have about 6 spare barrels and went over all of them to see which was the best. One seemed to have a smaller diameter hook piece that made no difference. They all look about the same. The one I chose actually looks to be a new part. Wartime parts are probably not as good as the ordinary. I suppose I should try to sharpen up the hook piece with a jewelers file, but that whole area must be taken down to allow the spring tip to get a good purchase on the spring. I'm leaning toward annealing the tip area and bending it for a good grip, or just leaving it alone and wind slow. Taking 2 days to do a 2 hour job is stupid, but I'm retired so...........
 

Skutt50

Registered User
Mar 14, 2008
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Gothenburg
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Are we talking about the barrel hook or the hook in the center by the arbor?

One old trick I have used is to file the main spring barrel hole. The idea is to sharpen the part of the hole catching the hook so it "digs in" under the hook tip.
 

Dave Haynes

Registered User
Sep 12, 2000
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Are we talking about the barrel hook or the hook in the center by the arbor?

One old trick I have used is to file the main spring barrel hole. The idea is to sharpen the part of the hole catching the hook so it "digs in" under the hook tip.
Hi Skutt, It almost surely is slipping at the center arbor. The stop in the barrel proper is a pretty radical piece of bent steel. When looking it over the end of the spring is always exactly where it should be and flush with the barrel edge. I would guess that once the hole end gets into that bent piece, it isn't going anywhere. Making the hole larger is interesting and easy to try. Thanks for the info.
Dave
 

Dave Haynes

Registered User
Sep 12, 2000
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Usually if a mainspring is slipping at the arbor, it desn't take much to hook back on. However, one needs to have the arbor in a pinvice and the lid off the barrel.
Problem with these Walthams is when the cover is off, the arbor goes with it. I did find one of my old bench keys that fits the square hole on the bottom of the barrel and that should help to narrow it down. I think the problem is that the tip portion of the spring that grips the arbor is pretty stiff spring steel and the tiny tit that holds the spring to the arbor is indeed tiny. I've done a lot of these and never had one this stubborn.
Thanks
D
 

John Runciman

NAWCC Fellow
NAWCC Member
Aug 13, 2003
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One of the things you have to be careful with Waltham and mainsprings is if it's the steel barrel just because it looks like it's hooked on the outer wall doesn't mean it is hooked.

If you look at original Waltham mainspring no notice that there is a bend by the hole and taper. In order for the whole to secure itself to the steel barrel it has to wage itself in to the protruding parts you can't just be there.. Otherwise it will continuously slip it may temporarily look like it's staying there but as soon as you put pressure it cannot stay unless it's wedged into the peace that comes out. This means if you have a new non-Waltham mainspring you have to modify the end or it's never going to catch.
 

Dave Haynes

Registered User
Sep 12, 2000
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John wins the prize. The barrel has a tiny little piece of sheet metal that is actually a stamping using the barrel rim, it cuts a square hole with one end left uncut and then the cut portion is pushed down creating a nice place for a mainspring end to catch and hold through the hole. That little piece of sheet metal was smashed and mostly destroyed by the spring. Use a bench key and look at the spring in the barrel and it was always where it should be, but it was slipping. I looked through my stash of 6/0 barrels and others were trashed the same way. There was rust around the cut opening on one of them. I picked out what looked to be a new one and placed the mainspring by hand making sure it was hooked and now all is well.
Thanks for your help
D
 

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