Abstract: A coreholder for securely holding web cores and the like for winding or unwinding includes a cylindrical body surrounded by an expandable sleeve for receiving a core with the sleeve extending within the central opening of the core. Grooves along the body surface beneath the sleeve hold balls of uniform diameter. The balls extend along the lengths of the grooves in contiguous relationship such that at least some of the balls are forced radially outwardly toward the sleeve for applying pressure thereto upon pressure being exerted relatively between the balls. One of the grooves opens from the body at one end for exposing an end one of the balls to selectively applied pressure by a tightening knob to transfer pressure to others of the balls, causing the balls to apply pressure to the sleeve for causing it to expand outwardly for uniformly and grippingly engaging interior surfaces of the core central opening.