Expert: Martin Meyer - 6/9/2007

Question
QUESTION: We have a grandfather clock (nothing horribly special) with a 1983 FHS movement 1151-050H. The pendulum got lost during our last move. The movement is stamped on the back 85 cm/70.77, which I assume is the pendulum size? Is it possible to make a pendulum, or is there a source for a replacement?

ANSWER: Hi Henry,
    Replacing your pendulum should not be a problem. What you are looking for is a complete pendulum assembly for a Hermle 1151 movement, which is 85 centimeters (33 inches) long. Your original pendulum was probably of the wood stick type, rather than the "lyre" (all metal with a row of metal rods) type. You should get a pendulum of the same type as the original. Some catalog listings will say "Hermle 1151" pendulum, some will just say "Hermle 33-inch" pendulum. As long as it is a Hermle 33-inch pendulum of the same type (wood or lyre) as the original, it will work. Make sure you get a complete pendulum assembly, including top hook, regulating unit and bob.  You can search the web for clock supply businesses. The two biggest are probably Timesavers and Merritt's Antiques, both of which are very good.  Thanks for your question.  Martin

---------- FOLLOW-UP ----------

QUESTION: Thank you for the speedy reply! I've been searching all the clock supply businesses, and have found several places I can purchase an 85-cm Hermle wooden pendulum. However, mine was a lyre type, and no one seems to carry them. Could I use the wooden pendulum to replace the lyre pendulum, or could you direct me to a clock supply business that might carry the lyre version?

Answer
Hi again,
    Merritt's Antiques' catalog lists a lyre pendulum for a Hermle 85 cm. movement, part number P-1557, at $45.00. The price may be out of date. Hopefully, this item is currently available.
    Here's where it gets a little complicated. The disk on Merritt's pendulum is 6-5/8" diameter. If your original pendulum was 6-1/2" in diameter or greater, then you're all set; the Merritt's pendulum will work. But, If your original pendulum had a small disk, less than 6-1/2" diameter, your center weight (which powers the pendulum) will be too light. My specifications indicate a 4.7 lb. center weight for lyre pendulums less than 6-1/2"; and a 7.3 lb. weight for lyre pendulums 6-1/2" or greater and for movements with a second hand. If your center weight is too light the clock may stop or not run at all. If you need to add extra weight, you can do it because the weight shells come apart and you can pour in some lead shot to compensate. The weight needn't be exact, but should be in the ball park.
    As far as the wood pendulum is concerned, you could have the opposite problem.  If you have the light center weight, you will probably be okay. But if you have the heavier center weight, it may overpower the light wood pendulum, causing erratic timekeeping, and possibly making the pendulum bang into the sides of the clock.
    Hopefully, all this technical detail will be unnecessary, and the Merritt's pendulum will be the correct one. This is the most likely possibility, as most 85 cm. lyre pendulums have disks of the larger type.
    Thanks again for your interest, and I hope this will solve your problem.  Martin