Expert: Martin Meyer - 3/1/2009

Question
I have an old clock that was suppose to be fixed by a local man. It has never been right. There is a wheel on the face of the clock that I think adjusts the speed, slow or fast. How do I determine which way and how much to turn the wheel.The clock is about 20 minutes fast right now. I would appreciate any help that you could give.

Answer
Hi Mark,

"Fast" and "slow" can be in either direction. Unless your clock is marked with an "S" and an "F" near the wheel, you will have to determine this by trial and error.  If you take the clock to a professional clock repairer, he will be able to examine the movement from the back and determine which direction is "Fast" and which is "Slow".

There is no rule for how much to turn the wheel, but it should be adjusted in very small increments.

Use this procedure to regulate your clock: Regulating adjustments should be made after the clock is fully wound, as far as it will go. Mainspring-driven clocks run a bit faster when fully wound, and a bit slower at the end of their weekly running period. Thus, you should run the clock for the full week before noting the timekeeping error and making another adjustment. In this way, you can average out the rate error so that the clock is accurate over a weekly period, but runs a bit fast when fully wound and a bit slow when almost unwound. It is extremely helpful to keep a record of how slow or fast the clock is at each weekly regulating period, and how much you turn the wheel. This prevents over-adjustments which keep you going back and forth between too fast and too slow. Finally, always check the clock against one very accurate reference clock. A plug-in electric clock or quartz watch is most accurate. Do not use battery/quartz clocks, any mechanical ("wind up") clock, or time announcements from radio or TV, as none of these are necessarily accurate. For super-accurate time, you can also call the US government's telephone time number at (303) 499-7111 for WWV (Colorado). This is NOT a free call.  http://www.clockmasteronline.com