[high_vacuum_house]

Good morning,
I have managed to find a way to repair a snapped clock spring fairly easily and so will share the tip here.
I bought a 60’s Metamic retro looking mantel clock which was listed as not working. After disassembly it was clear that the outer end of the mainspring had snapped off where is hooks over a lug in the brass barrel. Finding a replacement mainspring would have been very difficult.

This is hardened steel and absolutely no chance of drilling a hole in it!! Attempting to set a bend on the broken tip of the spring caused it to snap it was that hard.

What I managed to do to repair the spring was to put the last 1/2” of the spring into the flame on the ring on the gas cooker until it had got hot enough to glow cherry red and then carefully whilst the end of the spring was still in the flame with long nose pliers set a small 180° bend in the spring. At this temperature, the steel is malleable enough to be easily worked without fracturing. This was sufficient to hook over the lug in the brass mainspring barrel and allow the spring to be wound up and only losing less than an inch of the spring steel.

After careful cleaning and reassembly the clock now runs as it should with only a small loss of spring capacity. This method could be used with other small springs or hardened components that need to be worked. The only downside is that you do lose the temper and hardness in the steel at the area being heated.

Christopher Capener