Method for molding thin-walled spiral tube for use with endoscope

A method of molding a polymeric device having an elongated hollow tube and a spiral fin, the method comprising:

• injecting a liquid resin into a mold space defining the polymeric device, the mold space having an elongated hollow tube molding space for forming the elongated hollow tube and a spiral fin molding space wound around the elongated hollow tube molding space for integrally forming the spiral fin with the elongated hollow tube;
• and
• providing a longitudinal flow channel molding space path in at least a portion of a longitudinal length of the elongated hollow tube molding space, the longitudinal flow channel molding space defining a concavity greater in depth than other portions of the elongated hollow tube molding space, other than the spiral fin, such that the liquid resin injected into the mold space flows in the longitudinal flow channel molding space to fill one or more ends of the elongated hollow tube molding space.