running fast

[eyedoc46]

Hi,
A recently acquired Waltham pocket watch is running 15 to 20 minutes fast per 24 hours ! The regulator is set to the maximum “S” setting. Any suggestions as to what else may be causing this. Thanks for your help–Andrew

[arutha]

Probably an obvious one but is the hairspring touching itself anywhere? If coils are touching this can shorten the effective length and cause it to run faster? This can happen if the hairspring has been molested or oil has found its way on to it. Also if the watch has been apart and the hairspring pinned back in the wrong place again making it tighter?
Just a thought, sorry if Its not the answer.
Paul.

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Even if the hairspring is “in beat” that is oriented correctly on the staff, Bob in his watchmaking videos, made a very strong point that if the hairspring is either dirty or magnetized or for any other reason the hairspring coils touch the watch will run fast. (Bob- wasn’t this a quiz question?) You can make some assessment before taking the balance out of the watch as to whether or not it is in beat, being in beat means with absolutely no power in the watch or input from the pallet fork the roller jewel should stop in a postion that puts it facing the entrance of the pallet fork and right on a line between the balance fork pivot and the balance pivot. This assumes the pallet fork is a concentric design, I.E. the pivot location is on center of the pallet fork. One other thing to look for is to make sure the hairspring is routed correctly between the pins on the regulator and that one coil is not hooked over the center wheel of the watch.

Hope this helps…

Dave

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