Clocks

Introduction

Clocks are made to tick. If they do not tell the time, many people feel that they are not fulfilling their function. Modern clocks are easy enough to keep in working condition. As well, there is a large industry for clock repair and servicing. Old clocks, on the other hand, are not as easy to repair. For rare or historic clocks, it is sometimes questionable whether this should be done, or can be done without compromise. It may be that your clock will never tick again. It just depends on how complete and how deteriorated it may be.

Assessment

Before considering any repair work aimed at making an old clock function, a full mechanical assessment should be done. Whether the clock can or should be made to work will depend upon the following factors:

• All the working parts must be in good condition. This includes every tooth of every gear wheel, the axles and bearings, springs and any other working part.
• All working parts must be present.
• Gear wheels must show minimal wear on their teeth, and all teeth should be present. Each gear must engage on the adjacent gear with very little "play" or backlash.
• Axles must move smoothly in their bearings.
• Springs must be in good condition, with no evidence of cracking or loss of temper.
• Weights must be of the right mass and securely suspended.
• Chains, cables or strings for the weights must be in good condition, with no fraying, loose parts or other deterioration.
• The clock mechanism should be securely attached to the case, and not wobble or move in any way when pressure is applied.
• The clock should be securely positioned, either on the floor (for long case clocks) or on a shelf or bracket.  Long case clocks should be levelled and shims put under the feet to prevent any movement.
• The whole mechanism should be clean and free of dust and dirt.
• The mechanism must be lubricated with the correct lubricant in the correct quantities.

If all these requirements can be satisfied, it is possible to make the clock tick again. If there is any doubt about the completeness or the condition of the clock, it will be necessary to have the clock professionally evaluated and assessed. Such an evaluation should only be done by a clockmaker acquainted with historic objects.

Cleaning

Light dust on dry metal and wood parts can be removed with a soft paintbrush used in conjunction with a vacuum cleaner. Cover the nozzle of the vacuum cleaner with a piece of screening to prevent small loose pieces from being sucked up.

Old clock mechanisms are very often coated with sticky dirt created by the combination of oil and household dust. If too much oil has been applied, or if the wrong kind of lubricant has been used, this dirt build-up can be resistant and difficult to move. In an otherwise sound and stable clock mechanism, it might be the only thing preventing the clock from working. Dirt residue can be softened and removed with mineral spirits. Avoid using cotton batting or cloth because loose threads that are almost invisible can wrap themselves around axles and bearings, inducing friction and providing sites for future dirt build-up. Apply mineral spirits with a small artist's paintbrush and wipe off with a lens tissue. Use a toothpick or sharply pointed wood skewer to dislodge any resistant material. Axles and other pieces of circular cross-section can be cleaned by wrapping them with a length of thin, tough string soaked in mineral spirits. This is worked backwards and forwards, without applying too much pressure, until the dirt is removed.

Some proprietary clock-cleaning solutions also contain acids. Inexperienced users can cause damage to the parts of old clocks using these solutions.

Wooden clock mechanisms should be cleaned with extreme care, using only the dry brushing method referred to above. Take great care around the working parts. Wood is fragile even when new. Over long use, the parts can become badly worn, cracked and distorted. It is rarely possible to make an old wooden mechanism work effectively, and much damage can result from trying.

Do not disassemble a clock unless you have previous experience, you have the correct tools and workspace and are absolutely sure of what you are doing. Document every step for future reference.

Lubrication

Lubrication of metal parts must follow cleaning as soon as possible. Once dirt and old oil deposits are removed, the metal is very vulnerable to corrosion. Also, because the bearing surfaces are dry and subject to friction, the clock mechanism should never be operated until it is oiled. Only light machine oil specifically formulated for clocks should be used. A very small drop of oil should be placed on any jeweled bearings and on each metal-to-metal bearing, where the axle meets the supporting plate. The oil can be applied as a drop on the tip of a fine piece of wire, or a specially made oiler can be bought from a clockmaker. Use the smallest amount of oil possible and wipe away any surplus with a tissue.