You know when you get a wire spade terminal from the autoparts store and it is soldered and crimped perfectly...... How do you get the open ended connectors to crimp down so nice? Is there a tool to do this? I always seem to destroy the connector pieces using needle nose pliers. They're all bent every which way and flattened to a pancake. How do they get it so nice and rounded edge so it actually "bites" into the wire to hold it that much better?!! Thanks in advance.