Length of the clock mechanism axis – how to choose it correctly?

Clock mechanisms come in many versions, differing among other things in shaft length. Choosing the right variant is necessary for the mechanism to be properly mounted to the dial and for the hands to be attached.

Why is the length of the mechanism shaft important?

The shaft of the mechanism passes through a hole in the clock face. If it is too short, there may not be enough space for proper mounting of the mechanism and the hands.

On the other hand, using a significantly longer shaft than needed can cause the hands to be unnecessarily far from the surface of the dial.

What should be measured before purchasing a mechanism?

The most important measurement is the thickness of the dial at the mounting point of the mechanism. It is also necessary to consider the mounting method and any elements located between the mechanism and the dial.

Is the total length of the shaft and the length of the thread the same?

No. Descriptions of mechanisms may include different dimensions related to the shaft. It is important to pay attention to whether the given value refers to the total length of the shaft, the threaded part, or another structural element.

When comparing an old and a new mechanism, it is best to check the same measurement points.

How to measure an old mechanism?

If the old mechanism is available, it is worth measuring its shaft with calipers and comparing the design of the hands' mounting. This is often the simplest way to select an appropriate replacement.

Can a mechanism with a longer shaft be used?

A small difference in length may be acceptable depending on the design of the clock, but it is best to choose a mechanism as close to the original as possible and suitable for the thickness of the dial.

What else should be considered?

Besides the shaft length, the type of mechanism, the operation of the second hand, the size of the clock, and the method of mounting the hands should also be checked. For large and heavy hands, a mechanism with appropriately greater driving force may be needed.