Bring old springs back to life?

[SIGP2101]

Can one revitalise old springs that lost their elasticity. Whether being coil or leaf spring.
Does anyone have source of info on this topic. Temp graphs, cooling time, quenching oils, technique used etc…

Would you mind sharing your knowledge?

 

[ckid]

I have done this sucessfully with flat leaf style springs, I have yet to try it with coil springs, but it should work. I gently and uniformly heat the entire spring with an oxy/acetylene torch until they are cherry red and then quench in ATF. Next you polish of any scale or old blueing until you have bare shiny metal, be very careful with the spring at this point as it is at it's maximum hardness and is very brittle. The final step is to slowly and gently re-heat until it turns a blue color and quench it in ATF again. If you go past the blue phase you can start from scratch again. A note of caution, this process has worked well for me but with a variety of different spring steels out there it may not work with different alloys. I believe that most spring are fashioned from oil hardening varietys of steel rather than air or water hardening steels.

 

[mooncoon]

I have made at least 40 mainsprings while repairing muzzle loaders. The tempering technique should be identical to retempering or upgrading the tempering of an existing spring.
I heat the finished spring red hot and quench into water with a 1/2 inch layer of oil on the surface. I originally used the colour scale to draw the temper and drew to the beginning of grey; dark blue on a muzzle loading spring is too brittle and it will break. I next used molten lead in my electric lead pot; very uniform temperature application and drew to 680 F using a high temperature thermometer. For the last 5 years or more I sit the spring on edge on two 2" long finishing nails and 3/4 cover it with old automotive lube oil (in a metal tray). I heat the tray and oil until the oil boils and burns and let the oil burn away. When the oil has burned away the temper has been draw to spring hardness and the method has proved very dependable and easy.
One last thought is that do not forget that you need to return the weak spring to its original contour or dimensions before hardening and drawing the temper.

cheers mooncoon