I have a big bag of mixed nuts (hazelnuts, walnuts, pecans, Brazil nuts) in their shells that I want to crack open to enjoy later. I have tried to look up how to crack individual types of these nuts but they are all different. Can I just dump all the nuts in a barrel and soak them for a few hours until their shells are soft or will this ruin the nuts?
You really can't automate this. As you noted, each nut is cracked with a different technique and requires an individually independent amount of force.
Soaking the nuts won't accomplish anything desirable.