Mainspring Repair/Replacement

Example of a Mainspring That Has Taken a Set (Left)

This photo illustrates what often happens when a mainspring ages.  The old mainspring on the left is the same length as the new mainspring on the right. The left mainspring has taken a "set" meaning that it has lost some of it's springiness. The old coil has 4 extra turns of the spring permanently set. This means that it has lost four turns of strength and may not keep the clock running for a full week. 

Mainsprings are hard workers.  They store a great deal of energy.  Unfortunately, they don't last forever. If they don't fail by breaking, they can loose their effectiveness by taking a "set" (see photo).  If a mainspring is noted to be failing during overhaul, replacement springs are available for most clocks.  If a mainspring breaks while the clock is in service,  the explosive release of energy can often damage other parts of the geartrain.  Sometimes, a spring will fail at it's its end connection.  If the rest of the spring is still good,  the broken end can be removed and a new attachment point (hole or loop) can be fashioned. It's good practice however to simply replace a failed mainspring if it is still commercially available. 

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