I have been looking online and found there should be two points of contact, one in the blades and one in the pin. In order to achieve this, I assume there's a slight angle of the blades into the opposite blade.
However, I couldn't find any information about specific numbers. How would I go about designing scissors that ensure the aforementioned contact while not being too hard to actuate?
Before designing any scissor the crucial details common in every scissor must be covered as noticed in home scissors the following description are common-
The insides of the scissors are not flat. They are slightly curved towards each other lengthwise.
One of the screw holes is not parallel. It leans very slightly so that when you tighten the screw it pulls the tip of the scissors closer.
You can choose steel as a material to cut the scissor shape or pieces, if material is to hard you can perform annealing to loosen the thickness , to provide the bend hammer the steel to taper and make a bent.blades on scissors are bent towards toward the tip do that a proper cut throughout the whole length can be made.curving the tips can be achieved by gently heating the tips and tapping .Now we drill the screw holes to achieve that one hole is drilled at a very slight angle leaning away from tip with the screw holes drilled tap a thread and then scissors can be easily clamped.The scissor might still be brittle ,hence tempering can help to reduce the overall brittleness or hardness from the steel .after tempering the scissors are pretty much ready to use.
Yes, there is a gentle curve (not angle ) built into the blades, designed to counter the small play in the hinge. This curve holds the cutting edges close together but at the same time it should not be too much as to interfere with the smooth mechanism of the scissors, my estimate is the curve trace angle is under one degree.
It has to do with the stiffness of the alloy of the blades and what kind of heat profile they have been hardened with too.