Case tested XX Back spring

[Mytwins1999]

Just picked up this knife today,it has a broken back spring in it.I am going to make a new one and was wondering if it takes regular steel or are these made out of spring steel.This is a new hobby for me but have been interested in doing it for a while.Thanks Tim

[muskrat man]

springs must be made of spring steel and tempered correctly in order to spring. 01 and 1095 are both good steels to use for backsprings

[Mytwins1999]

Where is a good place to get the steel?

[rangerbluedog]

MM
I don't know what the proper HT technique is when using O-1 as a spring, but back in my tool&die days we would heat it to 1550F for 1/2 hour plus an additional 1/2hr. for each inch of thickness. Then quench in oil. Then, depending on the desired hardness we would temper (or draw) at somewhere between 300 to 1000 F.
If I remember correctly O-1 would end up in the 45-55 HRC range.
We never did any HT on carbon steels like 1095 (0.95%carbon). I'm guesing this would be done in a salt bath or induction hardened.
I always think of O-1 as tool steel, but then again in the engineering world - technically speaking - EVERYTHING is a spring!

What process do you guys use to HT these steels?

[muskrat man]

all my tempering is done bye eye. heat it up non magnetic and quench in oil. Then draw it back to a violet, or even a dark blue and quench in water, do this step 3 times to ensure that the steel has been softened all the way though. A soft "skin" does you no good when the core is still as brittle as glass.

[Hukk]

O-1 is one I have used. From my heat treaters guide it says to soak at 1200 F to preheat and heat the steel slowly on O-1, then soak at 1455 F to 1500 F (non magnetic) for 10 to 30 minutes and quench in oil for a quenched hardness of 63 to 65 HRC.

Tempering at 345 F to 500 F brings the hardness down to 62 to 57 HRC, fine for a blade. For backsprings a tempering chart shows that 800 F will put you around 50 HRC. O-1 is a forgiving steel. I also temper 3 times. Good Luck!