Abstract: The present invention provides a flexible support shaft assembly which is capable of bending transversely relative to its longitudinal axis or centerline with a predetermined limit on the bending range. The flexible support shaft assembly comprises a first helical member with a series of coils of round cross section and a second helical member with a series of coils of wedge-shaped cross section. The first and second helical members are coiled together along a common longitudinal axis with the round coils alternating with the wedge-shaped coils which separate the adjacent round coils from each other when the support shaft assembly is straight. The wedge-shaped coils are slidable relative to the round coils to allow the support shaft assembly to bend into a curved shape until the round coils on the inside of the bend engage each other and limit the bending range.