Mechanical WW Forster 1197 Date Wheel will not index cleanly

mur

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Nov 27, 2016
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I'm working on a Forster 1197 movement, and have a problem getting the date wheel to index properly. It will not snap cleanly into place, but sluggishly moves into a half-way position. You can see where it lands in the below photo.

The lever seems to be well tensioned and is applying what seems to me to be a good amount of pressure on the date wheel teeth. The date wheel seems to rotate freely, when I "pull" it around with a piece of rodico.

I have tried the following actions:

the first thing I noticed was that the two springs were not the same and seemed ill-fitting. I found some springs on ebay from a forster 196 movement (which seems to be identical for this portion of the watch) and indeed they seemed to perfom better.

I gave each tooth on the date wheel a little buffing/rubbing with a wooden peg stick in an attempt to remove any potential burrs (although I couldn't see any). Especially for two teeth positions that seemed to be worse than the others.

I added a little 9010 oil on the lever bearing surfaces and on the contact portion of the the lever and the teeth. This worked well at the beginning, and I was very happy thinking I had finally solved the problem, but when I came back to the watch 2 weeks later, it was no longer working.

I then removed the oil and tried lubricating per my interpretation of some instructions I found on this site from the British Horological Institution. Whether I did it correctly or not is open to question. No success. It was not snapping into place for any teeth.

I then tried with no oil whatsoever, also with no success.

I'm concerned that if I just oil it again and possibly get it working, there's no guarantee that it'll stay working, and I'd like to do it right.

Are there other things I should be looking for? Is it possible that the aluminum date wheel teeth are just wornout? Maybe bent teeth (out of plane)? Do I need to oil the "bed" that the wheel sits on? Or the in-plane bearing surface on the teeth? I saw one thread where the member cited the use of graphite in this area.

thanks

Peter

forster_1197.png
 

mur

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Nov 27, 2016
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Update: I tried graphite. didn't help. Then dis-assembled, and re-cleaned, thinking maybe I had lodged some rodico or something else. Still no results.

Would really appreciate any inputs, suggestions at this stage.

Anyone?
 

Skutt50

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Mar 14, 2008
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I don't know this movement but I have some thoughts in general.....:

1 - Could you possibly have a screw in the pillar plate that is extra long and in the wrong place. If so it could be sticking out through the plate where the date disc is running causing problems.

2 - There is normaly a small spring loaded lever that is "locking" the date disc in the correct position for each date. Is there any possibility the spring is turned 180 degrees thereby not pushing hard enough on the lever? (Has happened to me....)

3 - Is there something preventing smooth movement of said lever?

Is there some quick set mechanism? If so how does the date disc behave during quick set?
 

mur

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Nov 27, 2016
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I had a look at your suggestions, and it does seem that something is stopping either the free rotation of the date wheel or free movement of the levers somehow. There are no protrusions (screws or whatever) in this area. When I back off, a half turn or so, the screws holding the plates that secure the date mechanism in place, all appears to be working well: the date snaps nicely. When I tightened up again, same old problem. The quick-set works with the loose securing plate but not when the plates are firmly secured in place. I took out the date wheel, and it does appear to have a slight out-of-flat on the outer rim. I straightened this a bit. Not sure about the flatness of the inner diameter where the teeth are. I'll have a look at that and try to make sure it's fully flat. Maybe the securing plates (don't know the right name) have been bent at the rims where they are undercut to catch the datewheel teeth? I'll check that also.
I'll come back with an update. Thanks for your help!
 

mur

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Nov 27, 2016
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Ok, reporting back on progress as promised.
It turns out that the problem was the flatness of the date-wheel. I took out the lever and spring so I just had the date-wheel and the cover-plates in place. Rotating the wheel with the help of some Rodico, I could see that there were 2 spots where the wheel rubbed against the plates and stopped free movement. I suspect I pushed the date-wheel out-of-flat when I screwed in 2 screws from the opposite side to secure the movement to the case. (They were missing, and I was trying to select some new ones from my stock of screws.) I bent the wheel back gently, making sure to not kink it and make it worse. I also added a little height to the securing plate to give a little more clearance, by punching through the clearance holes for the screw with my staking set. Now it works great!

Thanks again Skutt50.
 

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