My friend and I decided to try to make a knife like a Buck 110 or Puma Prince but with modern materials and a different blade design. We decided to use a spring for the rocker of the same design as the 110. That is, it is a rod 45 mm long and 2.8-3 mm in diameter. The first 12.5 mm of the rod is fixed and clamped in the spacer. That is, only 32.5 mm of length are bent

When the knife is disassembled, the shaft is straight; when the knife is open or closed completely, the shaft has a deviation at the tip of 1.5 mm; when the knife is in the process of opening, the maximum deviation of the tip from the straight state is 5 mm

We also measured the maximum force to deflect the rod by 5 mm, it turned out to be 15 kg

We're on a very limited budget and don't have a forge or thermostatically controlled oven to run enough experiments. If there are craftsmen here who made folding knives, then we would be very grateful if they would give advice on what brand of spring steel wire is better to buy and how much rockwell to harden it?

I know that this is a fairly simple calculation, there are examples like in the last 2 pictures, but it seems to me that we need a reverse calculation when we have all the dimensions and I need to find the properties of the steel. But I don’t think very well and I wanted to first try empirically, for example, steel wire 1066 or 1055, but I’m not sure about the steel grade