The Rack Must Fall!

How does a cuckoo know how many times to call? Why is my clock only calling once when the hands say 3:00?

These are great questions, and the ingenious works of a mechanical clock can do it, but a few things have to be in proper adjustment. Here are some things to watch out for to keep your clock working, and keep your cuckoo calling the right number.

First, check the hands.

We already have an article about the proper alignment of a cuckoo clocks hands.



Second, check the rack.



Here you can see a picture of one of our cuckoo clocks with the dial removed. Circled you see a black, sickle-shaped part that we call the "rack." This part has a certain number of teeth on it that are counted by the brass pin to the right of the part.

Sometimes, through excessive handing upside down, this rack can get stuck in a position that is too high for the pin to count its teeth. In the picture below, you are looking at the clock mechanism from the back. You can see the top part of the rack as a black hump, sticking out of the top of the mechanism.



In the picture above, the rack is in a position too high for its teeth to be counted. With the rack in this position, the clock will only cuckoo once every hour, no matter the time.

This can happen due to excessive handing upside down, or sometimes during shipping.

You can see in this picture where the rack is lower and in the correct position, as viewed from the back:



The good news is that the clock can be fixed with a simple adjustment so that the clock will cuckoo the correct amount of times every hour. Simply take a long object, like a pencil, and push down on the hump of the top of the rack so that it falls below the top of the brass mechanism. This will allow the rack to fall so that its teeth can be counted.



Push down in the direction of the arrow.

After you have completed this procedure, your clock should begin counting more than once call every hour. You may have to readjust your hands to match up with the mechanism after performing this adjustment. Refer to this article again to make sure that the hands are set correctly.

Continue Time

Here's something interesting...

On this Continue Time clock, two out of the three pointers rotate around another pointer, instead of the central point on the clock face, as with traditional clocks. The resulting kinetic artwork, and functional clock, is continuously changing its shape during a full rotation of twelve hours. While creating mesmerizing patterns on your wall the pointers are still read as with any traditional clock. The Continue Time clock measures 105 centimeters from end to end; a full 12 hours will span a circle of 210 centimeters centimeters of wall.

[via Makezine]

Remember, there are more fascinating clocks of modern design here: www.northcoastimports.com/design

How to attach the hands

A lot of confusion can crop up with hands that aren't cooperating. For example, sometimes it may look as if you clock has stopped but in reality the hands just aren't moving because they are too loose on the shaft. Sometimes one hand might be turning normaly, while the other stays still. Sometimes your clock might not be chiming or striking or calling when it's supposed to, but does it just before or just after the hour.

If any of these things apply to you, don't worry, your clock isn't broken, it just fell out of adjustment.

Clock hands are purposefully kept finger-tight or friction-fit so that they can be easily adjusted. Many clocks have very different methods for holding hands on. Most modern clocks follow some variation of the cuckoo clock model (discussed here in great detail) but there are a few that still follow the traditional example of antique clocks.

The Tapered Pin is, to the clockmaker, as the nail is to the carpenter. This is an elegant, slender pin with a very slight taper. It's purpose is to go through a hole on the end of a shaft and its taper allows friction to hold it in place. The hole is often on the end of a rod with a locking washer between the tapered pin and the object it is holding.

Many things on a clock are held together with the tapered pin method. Dials are held on, movement plates are held together, and of course hands are held on with tapered pins.

In the picture below you can see the shafts on which the hour and minute hand fit. The larger shaft (which is tapered) is called the Hour Hand Cannon. This rotates slowly around the smaller shaft which is circumscribes. The smaller shaft is the Minute Hand Shaft. This is often (but not always) squared - either the whole length or just at the end.


In the picture above, you can also see where the tapered pin fits in the end hole.

In the picture below, you can see how the hour hand fits on the Hour Hand Cannon. In this example, the minute hand assembly has been left out for clarity. As you can see, the hour hand slides back: over the cannon. The taper of the Hour Hand Cannon holds the hour hand in place.



If your hour hand is loose, simply slide it back further on the tapered cannon in the direction of the arrows.

Below is a picture of the minute hand assemply and tapered pin. Here, the hour hand assembly has been left out.

In this example, the minute hand has a squre hole that fits directly onto a square shaft. This is not always the case. Sometimes the minute hand has a round hole which fits over a square washer or bushing - more similar to the cuckoo clock example here. What is important in the example above is the way that the locking washer pictured keeps tension on the minute hand. In this drawing considerable space is shown so that you can distinguish between the parts but actually there should be no space between the minute hand, the locking washer, and the tapered pin.