Blue tempered spring steel really isn't that expensive to buy, but forming some of the bends may have been problematic. I'm guessing they buy soft material and heat treat it. That should theoretically work, if heat treated correctly.
We've made a handful of them here, but all the bends have to be done by hand, and they wind up being relatively expensive. I'd be curious to know how they are made on a production basis.
The other thing to realize is that the strength of the spring depends a great deal on thickness. If you start at .015" thick, and go down only to .014" thick, the stiffness of the spring will decrease by about 23%. It's not uncommon that a springs is spec'd with .xxx thickness, and no one has it, so they just substitute .xxx-.002, not realizing it makes a big difference.
Last edited by tex_n_cal; 01/29/16. Reason: add last paragraph
