Abstract: An apparatus and method for inserting rigid cores into flexible tubing comprises a frame having a tubing retainer and a motor device, having a chuck and being mounted on the frame in spaced relation to said retainer for engaging and translating the core longitudinally and coaxially with respect to the tubing. A tapered tip is connected with the free end of the core, and a source of pressurized air is attached to the tubing in communication with the central, axial aperture thereof. An inclined leading edge of the tip is shaped to mate with the tubing aperture, and is translated into sealing abutment with the terminal edge of the tubing free end. Pressurized air is introduced into the tubing and radially expands the unconstricted side wall thereof to an enlarged diameter for inserting the core therein.