I quit using automotive springs about 4 years ago, when I had a "Forged in Fire" moment. My mechanic friend gave me some Corvette leaf springs, so one day I decided to make a chef's dicing knife (small cleaver). I had it nearly completely forged..when it cracked from the edge almost clear back to the spine. If the crack were half an inch deeper, the piece would have fallen in half! Sometimes such things can be discovered by a color changed at the crack..but this one gave no clue.
Closer examination, showed a stress crack had opened up..It had been invisible when I started. Obviously many, many miles of continuous flexing caused metal fatigue to set in. Same thing can happen to coil springs. No doubt new springs are probably fine.
So far as spring material is concerned, most vehicle manufacturers use carbon steels..such as 1095 or 1560.,.and generally do it right up through their line.
Frankly, I likely would not use a leaf from too large a truck. They are so thick, it takes a lot of useless labor to pound it down to.0035 to .0060 of an inch for blade thickness...and I have too much arthritis already..
Now I am going to remove some "mistique'..and I may get some custom knife makers peeved. Dee, don't feel bad about turning to an American, German, French, Swiss or Scandanavian carbon steel knife maker for your work blade..
For most of us , we use the same steel the quality knife makers use.. then we heat it to forge, do basic forging..then normalize. Follow this by grinding and then we get the tempering oil as close to 125F as we can to harden what I want hardened..then place in our oven at about 425F for about an hour to draw the temper. Then do finish grinding and then polish if desired.
With a good factory knife, the use the same steel and do basically the same things. Except..all those steps are done under supervision of computer controlled conditions..the heats, times and other conditions will all be more precise..so what does that tell you. Times temperatures and ambient temps all computer comtrolled..
I know I will get some mad, but for quality I say the best custom is not likely to be better, for use than a top quality factory knife. Of course, it is a nice feeling to enjoy owning a one-off "custom" knife..and nobody should deny that.
I have a bit of an advantage, in that I live in "knife country". Case (Bradford) is about 35 miles, Alcas "the knife makers knife maker" is about 25 miles, K-bar (belongs to Alcas) about 22 miles... and Ontario about 5 miles.
In fact, the boss man at Ontario is a fellow church elder with me..and sometimes I will pick up a mis-stamped machete blade or two (1095 steel)..to make knives from. That's nice, because the thickness is already set for most hunting/survival blades.
For those interested, perhaps I should make a few utilitarian blades for $40-$50 and offer them here on GBO. No fancy work, but a good basic knife for that price...and still "custom". My aim is to make knives which mimic the look of the 1800-1840 fur trade blades.
