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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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2nd Jul 2020, 3:15 pm | #21 |
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Re: Repairing old butler bell box (annunciator).
Heating to red heat, quench (dip in water) makes it very hard. Then you temper it by heating up again to a much lower temperature, usually to the point where it goes blue https://en.wikipedia.org/wiki/Temper...(639%20%C2%B0F). for springs.
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