a machine and method for forming a spring coil in a length of hollow , cylindrical thermoplastic tubing comprises clamping the ends of a predetermined length of cylindrical thermoplastic tubing between first and second opposing spaced clamping members . in the machine , these clamping members include aligned first and second sections of a mandrel . these first and second clamping members then are rotated relative to one another by a predetermined amount selected to be slightly in excess of 360 °, while the mandrels are simultaneously moved toward one another , to shorten the distance between the ends of the length of tubing , while the coil is formed . at the end of this relative rotation , the mandrel sections engage one another . the clamped tube , with the coil now formed around the mandrels , is rotated and simultaneously heated to the thermosetting temperature of the tubing . after a sufficient time to establish thermosetting of the coil , the heat is removed . rotation continues while the tube is cooled . following the cooling cycle , the apparatus operates to release the tubing with the formed coil in it from the machine .