In order to have balance in hand instrument:
Blade edge should be within 2 mm of the axis of handle
Blade edge should be within 2 mm of the axis of shank
Blade edge should be within 2.5 mm of the axis of handle
Blade edge should be within 2.5 mm of the axis of shank
Balance is accomplished by designing the angles of the shank so that the cutting edge of the blade lies within the projected diameter of the handle and nearly coincides with the projected long axis of the handle. For optimal antirotational design, the blade edge must not be positioned away from the axis by more than 1 to 2 mm.
Sturdevants operative dentistry 7th edition page e1