Antique Clocks/Pendulum Wall Clock.
QUESTION: Dear Tom
1 Is it possible to design and Construct a Pendulum Wall Clock where the pendulum can rotate 180 degree?. I. E Inverse semi circle.
2 Can the pendulum material be a non metal?. Example - Plastic?.
ANSWER: A pendulum with a 180 degree swing would not be accurate as pendulums are only accurate when the sine of half the swing angle very nearly equals half the swing angle in radians. At 90 degrees the sine is 1 and does not materially change as the angle changes small amounts. The swing angle of all pendulums varies slightly as the internal friction and main spring torque vary. The escapement of pendulum regulated clocks is designed to control the swing angle to keep the clock keeping accurate time.
A balance wheel and hair spring movement can rotate 180 degrees or even more as the hair spring delivers a torque proportional to displacement from the at rest position. Possibly, you could design a clock with a very large balance wheel and get the same effect. Hair spring and balance wheel movements are designed so the escapement pin on the balance wheel itself and a notched wheel or staff notch "parks" the pallet as the balance wheel completes its swing. Thus, the escapement on balance wheel movements is considerably different than that of pendulum regulated clocks.
Heavier materials such as lead, brass and iron are generally preferred for pendulums as the pendulum presents less wind resistance with these heavier materials. However, I have some cuckoo with wood pendulums which seem to run quite well. Since plastic weighs about the same as wood, I would say yes to question #2.
---------- FOLLOW-UP ----------
QUESTION: Dear Tom
Can we experiment with Plastic, Wood, Rubber, Glass, Concrete etc for Pendulum materials?.
Plastic and glass would make a good pendulum. I just purchased a cuckoo clock with a plastic penulum, however this has a quartz movement and while the pendulum does swing it is not part of the timekeeping package. Wood would probably be satisfactory for a bob, wood is frequently used for the pendulum rod. This is called a stick pendulum. I would not use rubber as it is too flexible. With lighter materials it becomes very important to feather the edges to minimize wind resistance. Denser materials are always preferred.
I have never seen a clock that spelled out the actual numbers One problem with it that I see is the language barrier. People of most languages recognize the arabic and roman numerals without any interpretation being required. Also, they would be more difficult to read from a distance instead of the relatively large single and two character arabic numbers.