click spring

[lad111]

The fun continues. Currently working on a Seth Thomas 124 Westminster Chime and I need to replace the spring click spring. I ordered one but its too long so I thought I would increase my skill and knowledge factor by shortening the click spring. The diameter needed is 1″ and the replacement is 1.5″ and hence too long. Whats the best way to cut and reshape the click spring? I’m guessing heat it up and re-shape then cut to size, but would appreciate any input.

[Bob Tascione]

Hi Lad111,

The following assumes that the steel used is the same high carbon steel used in the original spring for this era and not a modern alloy. The temp. range can fluctuate a little depending on the steel used but most carbon steels will fall in the following range.
If you only want to cut or grind the spring off shorter you should be able to do this without heating. If you would like to reform the spring then you would heat (anneal) it as you suggested by bringing it to a cherry red color and then allow it to slowly cool down. This will soften the steel to allow bending. After you reach the shape and length you’re after you will then need to harden and then temper the spring. You would again heat the steel to a dark orange or cherry red color and then quench it in water. Heat treating oil is best used when heat treating modern steels that allow for oil quenching but not for older medium and high carbon steel. After heat treating the steel will be very hard and brittle. Any bending at this point will break the piece. You will then need to temper it back to a tougher spring steel hardness by first cleaning the part with a piece of steel wool or fine emery paper to the point where it is clean and shiny steel. This will make it possible to see the color change that is necessary for the tempering process. If the spring is a blue color before starting this process then make note of the shade. This will be the color you will try to reach during tempering. If not blue then slowly heat the part until it reaches dark blue and then as it passes into a light blue color remove it from the flame or oven. If using a flame try to remove the piece slowly from the flame to allow for slow cooling. If using an oven then after reaching desired temperature (color) turn off the heat and leave in the oven until cool. It should be ready to use after tempering.
Heat treating can sometimes cause warping of the part so you may wish to wrap it in iron binding wire to help keep it’s shape.

Hope this helps!
Bob

[lad111]

OMG I’m not sure I have the courage to do this. Is there a source that may sell the correct click springs for this clock? In any case thank you very much for taking the time to explain this procedure.

Lou

[Bob Tascione]

Hi Lou,
It sounds much harder than it actually is in practice. The whole heat treating and tempering process that i covered above would take just a few minutes. Making springs and heat treating parts can prove very valuable when you get into restoration work but there’s no rush if you’re feeling a little overwhelmed. I thought it was important to let you know that just heating the part up wasn’t going to be enough and could cause a little aggravation when you discovered that the spring was no longer a ‘spring’ after annealing it. When you have the time you can mess around with some scrap pieces of steel. It’s very satisfying work.
As far as sourcing a new click spring for your ST 124 I would think that contacting a few of the supply houses and asking them for that 124 click spring should do the trick. Not sure though so I’ll hunt around a little up here to see if I can locate a supplier for you.
Take care for now Lou,
Bob

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