Expert: Martin Meyer - 9/17/2007

Question
my sligh grandfather clock chimes on the quarter hour; however, the minute hand lands 5 mins after each quarter hour - that is when the chimes go off.  For example, instead of chiming at 12, 12:15, 12:30 etc., the clock chimes at 12:05, 12:20, 12:35.  i moved the minute hand back to make up the time, but was not able to gain any accuracy.  any suggestions?

Answer
Hi Ken,

The adjustment to correct the minute hand on your clock is not difficult.
    Stop the pendulum. Set the clock by turning the minute hand just to the exact point where the clock chimes on the hour. Remove the nut which holds the minute hand on, then remove the minute hand by pulling it straight off so that you do not change the time on the clock. You will notice that the minute hand has a round brass part with a square hole at its center. This is the minute bushing.
    Your problem probably occurred because this bushing has become loose on the minute hand. Place it face up on a hard surface like a piece of metal or anvil, and tap on the center of the hand gently with a very small hammer. This should tighten the minute bushing, keeping it in position.
    Next, insert something like a small screwdriver into the square hole in the bushing, so that it holds tightly in the hole across the diagonal of the square. I use a screwdriver that has been ground into a tapered square shaft, but a regular small screwdriver of the right size will work. Now, holding the minute bushing tight so that it does not turn, turn the minute hand backwards a tiny bit. Hold the hand near its base so that you do not bend it. The minute hand will rotate backwards a tiny bit, barely enough for you to notice, on the minute bushing. There will be some resistance, because the hand should be tight on the bushing.
    Put the minute hand back on the clock, being careful to put it on pointing to the hour, as it was when you took it off. Replace the hand nut. Check to see that its position now points exactly to the "12". You will probably have to make several adjustments like this before you get it to point to the correct position. Then turn the hands very slowly to see that the hand is pointing exactly to each quarter when it strikes.
    This adjustment requires some patience, as the amounts that you are turning the hand on the bushing will be tiny. Also, be very careful to replace the minute hand to the correct position each time; the square hole in the hand bushing can go on in any of four positions, so you do not want to replace the hand pointing to an incorrect quarter. With patience, you should be able to get the hand correct within 20 seconds of each strike point.