There are two distinct types of Quartz movements:

Chinese type

These movements have a round minute hand shaft. The disadvantage of these is that the minute hand can slip on its shaft. For example, if it's mid-day and you move the minute hand to half-past, the clock could end up with the hour hand still pointing at 12 and the minute hand pointing at half-past.

There is no fixed standard for the diameters of round shafted movements, so check the specification of the movement if you want to re-use round shafted hands.

Chinese type movements are also made in countries other than China. For compatibility, some German factories offer round shaft movements.

European type- Also known as I-Shaft

5mm hour roundshaft and 2.8 x 3.5mm minute shaft.

These have a round minute shaft with two flat sides. The advantage of this is that if the time is changed by moving the minute hand (not the setting knob on the back) the minute shaft must move, keeping it in sync with the hour hand. The minute hand is held in place with a small nut that often has a hole in the centre for a second hand shaft.

• Almost all standard movements require a 10.2mm hole in the dial.
• Movements are available with differing shaft lengths to cater for different dial thicknesses. Some vendors advertise the maximum & minimum dial thickness. The is much more useful than knowing the total shaft length.
• If the shaft is too short you will not be able to screw on the retaining nut. Too long and the shaft might touch the glass, although you may be able to add extra rubber washers.
• Clock hands should be as close to the dial as possible. This reduces the parallax effect. That is, a vertical minute hand too far away from the dial can cause the time to look different when viewed from the side.
• Not all movements are equal. Some have better quality crystals, making them more accurate. Some have more torque than others.

Fitting is very easy.

Simply put the movement behind the dial and screw on the nut. A rubber washer between the movement and the dial will reduce any ticking noise. Some clock cases can create a sound-box effect like a musical instrument does, amplifying the ticks.

Round shafted hands can be fitted in any position and moved to mid-day. Then use the setting knob to  move them to the correct time.

I-Shaft hands need you to put the minute hand on its shaft and move it to 12 using the setting knob. Remove it and fit the hour shaft to 12. Then put the minute hand back, aligning it with the hour hand and screw on the retaining nut.

Adding a pendulum

Pendulum drive units can add an attractive feature to a clock, especially nursery clocks, with wagging tails & moving eyes. They require their own battery and the swinging of the pendulum has no relation to the timekeeping. It's purely decorative and the pendulum doesn't need to be any particular length.

Fit the clock movement into the body of the drive unit and fit the movement in the normal way.

Repairing Your Own Clocks by Mervyn Passmore