Reviving tired springs

[chunnybh]

Hello,
When springs get tired, I usually replace them, but what to do when you can't find a replacement.
e.g. I have a tired Mikiphone spring and I can't find a new replacement. Is they anyway to revive the spring?

[emgcr]

Here is the AI response :

Re-tempering a tired steel coil spring is a multi-step heat treatment process involving annealing, reshaping, hardening, and final tempering. This is an industrial process that requires careful temperature control and proper equipment (like a heat-treat oven or a forge); inconsistent results are common in a home setting,
and safety precautions are essential.

Required Materials and Safety

Safety Gear: Thick gloves, safety goggles, and a face mask.
Heat Source: A forge or high-temperature oven is best for even heating; a MAPP or propane torch may work for small springs.

Quenching Medium: Quench oil (specifically formulated or even vegetable oil/motor oil, though with fire risk) is typically used for spring steel. Water is too rapid
and can cause cracking.

Cleaning Supplies: Sandpaper or a wire brush to clean the surface to observe tempering colors.

Optional: A brass or copper block for even heating during tempering, or a temperature-controlled oven for precision.

Step-by-Step Process

Anneal the Spring (Soften it)
Heat the entire spring to a dull red or cherry-red color.
Allow it to cool very slowly. Burying it in warm sand or vermiculite can help slow the cooling process. This removes internal stresses and makes the steel soft
and workable.

Reshape the Spring
Once cool, reshape the coil spring as needed to achieve the desired free length and form. All shaping must be done in this soft (annealed) state.

Harden the Spring
Heat the shaped spring to a bright, non-magnetic cherry-red color (around 1,400–1,600 °F or 760–870 °C, depending on the steel's carbon content).
Immediately and quickly quench it by submerging it vertically into a container of quench oil. Move it around in the oil until it is completely cool and stops
bubbling.
The steel will now be very hard but extremely brittle, so handle it carefully.

Temper the Spring (Draw the Hardness Back)
Clean the surface of the spring to a bright metallic finish so you can see the oxidation colors.
Reheat the spring slowly and evenly to a specific temperature range to achieve the correct balance of hardness and flexibility (toughness). For most springs,
the goal is a deep blue color (around 550°F / 290°C).
This can be done using a temperature-controlled oven for consistency, or carefully with a torch by heating a brass or copper block and placing the spring on it.
Once the desired color is reached, remove it from the heat and let it air cool.
Test and Finish
The spring should now be hard but flexible.
Professional manufacturers also employ processes like shot peening and scragging (compressing to a specific height) to further improve durability and set the
final length.

[JerryVan]

Check out clock spring suppliers. I did that once for a small spring, (which I assume the Mikkiphone would use).

[chunnybh]

Quite simple then.
Harden the spring by heating to 870°C and quench in oil, then temper it at 290°C.
Off to mates kiln.

[emgcr]

Yep.

[chunnybh]

Success!
It took a while for the kiln to heat up but then the hardening process was easy. Quenched in car transmission fluid. The tempering was even easier.
Thanks for the advice.