Left Hand Dies are called for in designs that require objects to move in opposite directions on the same drive shaft. These dies give the engineer greater flexibility when designing prototypes. Left hand dies can be used to create left handed shafts, often used to lock wheels in place and prevent loosening during rotation. Use Left Handed Dies with Left Handed Taps. The precision quality of these tools provides an accurate clean-cut thread, desirable where liquids, steam or air under pressure is involved.