Expert: Kenneth Saunders - 1/6/2007

Question
Hello Ken,                  1-5-07




I need a lyre pendulum for my grandfather clock. The movement is a Jauch 110cm made for Emperor Clock Co. The pendulum is 38 1/2" long from tip to tip, the bob is 6 5/8" in diameter.

The orginal pendulum is a wooden stick type. I want to replace it with a lyre type.
QUESTION: If replacing with a lyre type, does the lyre pendulum have to be an inch or so longer than the wood type?

The arm that goes from the suspension spring post to the pendulum is about 5" long, that with the pendulum makes it around 43.31" long = 110cm.

The inside of the clock case measures 12" wide (side to side), and the present set-up has an 11" swing.
QUESTION: How big of a bob can I use? e.g. 8 1/2" = 220mm, 6 1/2 = 165mm, etc.?


Do you have the pendulum hook, from the top of the pendulum to the suspension arm?

Can you recommend another brand that I may be able to retrofit to my clock? Hemele?, etc.?

Please let me know, and have a
Happy New Year.

Sincerely,

John Lyman
jlyman67@netscape.net

Answer
John, honestly I would recommend you hold your breath till
you forget about doing this at all. But here are some pointers- you gotta stay with the 6 5/8 disk. a lyre pendulum is heavier and has more weight above the center of the disk compared to the wood stick and thus needs to be a bit longer (inch or so)Hermle uses a heavier center weight also to drive the lyre pendulum than would have come with the wood stick- so do not know if indeed your clock movement would actually drive the new pendulum with out getting heavier center weight to match the one on the chime side. Jauch of course is long out of business. Their movements were marked on the back plate with numbers to id the pendulum length ie: 64  77 78 93 116 etc. Hermle makes conversion kits to replace the movement and reuse the pendulum. Hermle pendulums would be ok if you were going to do this. You are going to have to make up a hook for the top as needed to go on to your 5" pendulum leader- depending on how your Jauch is set up you might could bend the hermle to work. The upper last length of a new lyre pendulum just below the hook can be cut and a piece of brass soldered in to lengthen it if needed (doesn't show from the front)you can tape or wire together the pendulum parts for testing to see how they work without cutting things up.
Again- if a customer asked me to do this for him, I would instantly refuse the job!
You can consult with Black Forest Imports at 800 824 0900 about buying the Hermle pendulum - Ken in AZ