Expert: Martin Meyer - 6/25/2007

Question
I have recently had my 8 day west minister mantle clock serviced by a so called professional after it had stopped working.It will now run fine but i cannot seem to get it to keep good time. It seems as though as soon as i get it running somewhere near then re-wind it it goes 20 minutes fast each day until the wind is in its last few days then it will run ok again.

Answer
Hello Guy,
    I must presume that this is a mainspring driven clock, not a clock driven by three weights. It sounds very strongly like you are underwinding the clock. I notice that you say you get it running fairly accurately, then rewind it.
    8-Day mainspring clocks must be fully wound once a week. Make certain that you wind the clock FULLY, as far as it will go, on all three winding holes. You need not worry about overwinding, and you won't do any damage unless you put all your strength into it and break the mainspring, which is tough to do.
    The time to adjust the regulation is when you wind the clock: wind the clock fully, set the time by the same accurate clock every time. Don't use a wind-up clock or the TV as your standard. A quartz watch (not a quartz clock) or a plug-in electric clock is ideal. Let the clock run for seven days without resetting it or making any more adjustments, then note how fast it is. Make an adjustment to slow it down, rewind it FULLY, reset the time by the same standard clock you used before, then let it run for another seven days without adjusting or resetting it. Repeat this procedure until the clock is accurate. The limit of accuracy for a mainspring clock is a couple minutes per week - but it will take several adjustments and some patience to get there.
    The most common problem I come across with mainspring clocks is underwinding. People are afraid of "overwinding" it (there really isn't any such thing), and give the clock a couple winds every day or two. The result is that the clock is always running on almost completely run-down mainsprings, and so doesn't keep time accurately. It is essential that you do not do this, but instead wind the clock all the way once a week.
   I hope this information solves your problem. Thanks for your question.  Martin.