i'm not too sure on this, but i imagine it's similar to balancing a two bladed prop. If you have a prop balancer, put the prop on it and take note of wich blade falls. Then take some finger nail polish and put a dab on the light blade. Repeat this untill the prop stays in whatever position you put it. I.E. prop doesn't fall to one side. For a three blade, I would apply polish to one blade at a time. Maybe someone with some 3 blade experience can chime in here.