Over-winding a clock is a common myth.
The world of horology reveals an assortment of interesting expressions as well as the misuse of words and terms. For classic example; why do some refer to shelf clocks as Mantle clocks when a mantel is something you wear like a shawl or a cloak? Mantel, such as a shelf over a fireplace, is the correct term.
I want to focus on one very common expression. How many times have you the heard the expression, “it was running fine till I over-wound it”? I have heard it often enough on clock forum, Facebook sites and among acquaintances. It is an ubiquitous expression. Do not blame the last person winding the clock for they are not the cause of a so-called “over-wound” clock or one that stops mysteriously.
While it may be technically accurate that a mainspring can become damaged by repeated over-tightening that is, winding the spring until it is tight, and then continuing to tighten it more just to be on the safe side, there is another reason why this occurs.
Take a spring barrel like the one in the following photo.
When the spring is wound it is coiled tightly around the winding arbour. The other end of the spring has a small hole which is hooked over a small stud, which is riveted into the interior wall of the barrel.
The hole in the spring can become fatigued because of years of repeated “over-tightening”, and/or the stamped hook or riveted stud breaks free. “Over-winding” is not the reason.
A dirty movement
American open mainspring clocks “appear” to be “over-wound” because of a buildup of old oil, rust and dirt in the mainspring coil which causes the coil to stick and the spring to seize.
Clocks which might appear to be “over-wound” and non-working can be persuaded to run again by letting down the mainspring completely with a let-down tool, liberally applying mainspring oil and rewinding. This procedure is by no means a substitute for a good cleaning and it does not address other issues that may be causing the clock to stop but it is one step in troubleshooting your clock movement.
It is only when the movement is disassembled and the mainspring is removed from the arbour that you can examine the condition of the mainspring and decide whether to keep it or replace it. Dirt and old oil can be easily cleaned up. Light rust on a mainspring can be removed with emery paper or steel wool; heavy rust and the mainspring should be replaced. Inspect the spring for cracks or breaks. In many situations the mainspring can be saved.
In some cases the click can let go because the rivet securing the click becomes fatigued. For example, Sessions clocks have weak clicks and rivets. Inspection and remediation of a bad click is a typical procedure when servicing a Sessions clock.
Do not expect a newly acquired clock to have been serviced recently or at all unless the seller can prove it. Moreover, servicing a mechanical clock on a regular basis is an important part of ownership.
“Over-winding” is one of those terms that one hears quite often and is a very common myth.