We have been fooling around with worn out mudmotor props, and have been able to salvage a couple. We weld up worn edges with s/s rod and then using small disc grinders reshape and cup blades. We have done two from Mudbuddy motors with good results. Balancing is hardest, getting both blades equal in shape and thickness. I have been running one since this spring and haven't had any problems. With a little patience and slow going on grinders you can come up with a serviceable prop. Surface drives run with half the prop out of water so cupping is important.