Service intervals for antique and vintage mechanical clocks?

It is not uncommon for a mechanical clock to run 25, 30 years or more with nothing more done to it other than the occasional oiling.

How often should a mechanical clock be serviced? It is not as simple an answer as it seems.

In this post, I will discuss what it means to service a mechanical clock and explore some of the factors that influence how long a clock’s movement will last and how to prolong its life. Those factors will help you decide the best service interval for your antique or vintage clock.

Elisha Manross 30 hour movement
A very dirty 30-hour movement from the 1850s

If your clock does not work, cleaning it is the first step in determining the problem. Cleaning is just another word for servicing and the term “servicing” in the realm of professional clock repair implies a complete disassembly of the movement.

Though a common practice in the past, dunking a movement in a solvent and hoping for the best is not a substitute for servicing. Servicing a clock means that it is taken apart, inspected, assessed, cleaned, wear issues noted and damage due to abuse or failed parts is addressed.

What to look for

Normally clocks in my collection are inspected on a 3-4 year cycle. I will open them up and check the condition of the movement and if dry, re-oil. If I notice a particular clock stops occasionally and I find need to investigate, I will service it simply as a prudent measure. Clocks that stop occasionally are sending a clear message they require servicing.

If I notice that I am not getting full power during the clock’s designed running cycle I will investigate. For example, if a clock consistently stops at day 4 or 5 of its eight-day cycle this tells me that the movement might be very dirty or that there are worn parts causing the clock to stop prematurely.

I generally take the movement out of the case for inspection. As I inspect the movement I look for green or black residue around the pivots which indicate a more serious problem. It is at that point that dirt and other contaminants are mixing with the clock oil and producing an abrasive paste. This paste plays havoc with bushing holes and pivots.

The movement must be inspected closely and at a minimum, disassembled and cleaned. Once disassembled I will inspect parts for wear and determine if the wear should be addressed immediately or at some point in the future.

one-weight Vienna wall clock
Miniature one-weight Vienna wall clock stopped and after a cleaning runs much better

Let’s look at some factors that affect wear on a movement.

The clock’s environment

The local environment is the greatest factor affecting the life of a mechanical clock. In today’s homes, humidity and temperature can be controlled very effectively. However, there are always occasions in the year when the windows are open causing humidity to rise in a home. A clock may run faster or slower if there are changes in the home’s humidity as wood and metal expand and contract. Constant temperature and humidity in the home environment will definitely improve a clock’s performance.

Older homes with poor insulation have environments that are more difficult to control especially in kitchen areas where clocks are exposed to higher humidity and particulates from cooking. Clocks in homes with a wood heat stove tend to attract dust (though most modern wood stoves are well sealed) and the presence of pets will shorten the lifespan of clock pivots.

Dog and cat hair in suspension will get into the workings of a mechanical clock by wrapping around the pivots. Eventually, it is the reason the clock requires servicing.

I use an Excel spreadsheet and record any changes I make to a clock in my collection

The amount of dirt and dust (and animal hair) entering the movement is determined by how well the clock case is sealed. There is a very good reason why you should have an access door on the back of your mantel clock and if it is missing it should be replaced. Movements in high quality, well-sealed cases will run many years with minimum maintenance.

U M Muller box clock, and example of high-quality case construction

What are the signs that something is amiss

Spring driven time and strike clocks typically exhibit more wear on strike side pivots due to the hourly striking action. Yet clocks, especially American time and strike ones, will tolerate pivot wear and still run reasonably well if very worn.

It is very common to install many new bushings on an American clock. But sometimes I come across a movement where one side is much more worn than the other. I recently worked on a movement that required six bushings on the time side but none on the strike side. Evidently, a previous owner was bothered by the noise and the strike side was rarely wound.

With chiming clocks, the chime train is first to respond to additional friction caused by dried oils and dirt. The additional complexity of the chime side means that more parts are subject to wear. The chime will eventually slow down then stop altogether.

Fleet Time Westminster chime mantel clock circa the 1940s

If your weight-driven clock stops before its designed cycle, check for twisted cables around the winding drum and ensure that it is correctly in beat. Otherwise, a weight-driven clock does not tolerate pivot wear well and will need to be taken apart to investigate for that and other possible issues.

Sits without running

What happens when a mechanical clock sits without running? Time and environment are the biggest enemy – not operation. The only deterioration on an unused clockwork would be the oil as the oil will thicken and break down over time. Many clockmakers claim that synthetic oil is less prone to breaking down, something to consider for your prized mechanical clock if you do not plan to run it regularly.

Parts that are not moving for extended periods of time tend to fuse, and rust builds up faster particularly in high humidity environments. All mechanical things age better when running occasionally and so my advice is to let parts move from time to time. Run your valued mantel clock at least once per month to give it the exercise it needs.

This Schatz triple chime clock is “exercised” once per month

The environment in my home is controlled, the temperature is constant, the humidity is low and we do not have pets much like a museum environment. Having said that, I continue to schedule a health check on my clocks as a preventative measure.

I use an Excel spreadsheet to track and record any changes I make to a clock including information on service intervals and issues regarding the servicing of each clock in my collection. I want my clocks to last and some I would like to pass on to my children.

2 thoughts on “Service intervals for antique and vintage mechanical clocks?

  1. Thanks for the clock maintenance advice Ron. Maybe I’ll take apart the movements in my art deco mantel clock, one day, to clean. I’m always surprised at how much dog hair gets inside my computer tower! So can see how that would be a problem with clocks. Beautiful antiques to pass onto your children one day 🙂


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