Clocks, Watches/Jauch P64 Movement
QUESTION: Good morning, I have a question about pendulum length for the Jauch P64 movement. What pendulum length or lengths was it offered in?
I am going to replace the movement with a Hermle 451-050, and need to know what PL movement to order. The clock the Jauch is in is quite tall 88 inches and whatever pendulum is on it is quite short for the length of the waist. So I was thinking of ordering the 114cm version of the 451-050.
ANSWER: Tim, I apologize for the delay in my answer. I had misplaced my Jauch Tech Manual and did not let you know I was working on it.
Thanks for the good photos. They help in determining what you need. First, it is difficult to determine the "exact" pendulum length noted by a clock manufacturer, as they measure from different points. For instance, Jauch measured from the center shaft of the movements to the center of the pendulum bob. Other manufacturers use different reference points. My manual does not show a PL64 in any of the movements, only PL61 and then the next is a PL78. I think that is correct as my manual is at the shop. However, that does not matter, as you will be converting to a different manufacturer's movement. Of course Jauch has been out of business for quite a few years. Also, the door is of solid wood with no glass, so the length of the pendulum does not really matter as it is not seen with the door closed. You just have to use a pendulum that is the right one for the movement. I would suggest that you use the Hermle 451 94cm movement. There are 94cm pendulums made for that movement, or we can possibly modify your original pendulum. The reason I suggest the 94cm movement is that there is a conversion kit for changing from a Jauch to a Hermle. It consists of the movement, hands, mounting shims and screws, pendulum top hook and a 6.6# lead weight filler required for the chime side. I'm not sure of the other two weights used on your PL64 but they would have to be 4.4# or 4.7# each. I can give you some sources for the complete kits, but I do have them and offer detailed instructions and photos plus phone and email support for the project. There are also a couple of configuration details that have to be considered. If you will, contact me at my shop email address below and I'll be glad to give you further details.
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QUESTION: John, thank you for the prompt reply.
Shims? I assume that these are to raise the movement on the seat board. Correct? If so, how much does it have to go up? I have made shims before for this purpose out of aircraft-grade plywood because it is available in .0156 increments, also out of precision 110 copper shim stock for the same purpose. I make both types to be the entire width of the movement plates.
Face of this clock is attached to the dial frame not the movement, so I have some room to play around with the dial placement relative to the center of the hand shaft.
I was thinking of the 114cm movement since I have a new one on hand with weights and pendulum. However, bob diameter may have to be adjusted due to available space in the interior of the waist.
Tim, since you had said you were going to order the movement, I had suggested the 94cm. But if you have the 114cm, it should work as long as there is enough room for the pendulum to hang and swing without hitting the sides of the case. I don't know the width of your case or the swing of the pendulum with the original pendulum bob, so you will have to measure the swing on a test stand and choose the proper bob. A smaller bob will change the regulation a little, so it will have to be adjusted accordingly. The shims in the kit are for the conversion for the Jauch 77 to the Hermle 451. I would suggest you measure the difference between the bottom of the plate on the Jauch to the center of the handshaft and the same with the Hermle 451. The difference will be the thickness that you make the shim. For better stability in mounting, the shims supplied with the kit are about 2 inches long and are perpendicular to the plates. A hole is drilled in each for the mounting screws. You will also have to have longer mounting screws of the same mm thread.