We have been cracking our black walnuts. It is not difficult to do, but the nuts are really hard.
First, you have to crack the nuts open. We have found good ways to do this, with a hammer or in the vise. To hammer, it helps to have some way to hold the nut still besides your hand because it would be easy to hammer you hand by accident. Then, hit the walnut on the sharp point until it breaks. Or turn it on its side in the vise and tighten the vise till it breaks.
It is easiest to finish opening if they are in at least four pieces.
Use wire cutters to clip the shell away from the nut meat (also called a kernel).
