Getting bridge to sit on Gears and Pinions !

[DarrenThomson]

Hi there

i am working on an old Smiths Empire movement (cheap thing from the Welsh factory - only has jewels for the balance.. I'm having a devil of a job lining up the escape wheel, 2nd, 3rd and 4th wheels with the bottom of the movement and the bridge that holds them in place.. They "wiggle" in their sockets and this makes it really hard to lay the bridge over them.. No jewels in the bridge or the movement body - "metal on metal".

Does anybody have any little tips for this job ? Somebody was once banging hundreds of these out in a factory so there must be a technique !

Maybe an innovative use of Rodico ??

Thanks

Darren

[WileyDave]

Darren,

I have had some success with positioning bridge until almost aligned with pivots then prodding the wheels (gently) from underneath until the bridge drops into place. It's time consuming to say the least and you have to have enough access under the bridge to fit a long thin needle like tool or toothpick. I suppose you could use the rodico to hold the bridge with one hand and try manipulating wheels with your other hand.

1 hour ago, DarrenThomson said:

Somebody was once banging hundreds of these out in a factory so there must be a technique !

If you did this all day, every day, chances are you'd get to be pretty good at it!

Dave

[Ishima]

You have to combine a couple of different methods, but basically line everything up reasonably well, gently lower the bridge (baring in mind it wont be lined up), place the bridge screws in if possible, but tighten them only so far as the bridge will be kept vaguely in place, Then you can combine gently wiggling of the bridge (which i do with a cot covered finger) manipulating of the wheels with pegwood (at which time you'll want to let up on any downward pressure on the bridge), and with great care, patience and perhaps a good eye -- to see which wheel is off two degrees in what direction -- you can usually line it up so that everything will slip into place. tightening the bridge screws gradually as you go, checking for problems, once you think you have it, continue to finish tightening the screws but do keep checking for problems, see if the gear train runs properly, if it doesn't you might make matters worse by screwing the bridge down firmly. 

That's the approach that works for me anyway, others might have better things to say.

Edited January 21, 2017 by Ishima

[oldhippy]

I did the same as Ishima has explained with one exception I didn't use pegwood I used my tweezers. 

[Tcarpilot]

One thing that really has helped me when doing this is to work in a direction.  By that I mean after putting LIGHT pressure on one edge of the bridge, try and get the pivot of the closest jewel in first, then move onto the next closest jewel etc.  Sometimes I find that if it is not working at the original pressure point, I change to the other side of the bridge and start again.  GENERALLY I find starting on the escape wheel side is best as it has the smallest (read hardest to find) pivot and the center wheel the largest (easiest) to locate pivot.

 

Hope this helps!

Eric