Abstract: A chuck for grasping the internal cylindrical surface of a glass tube. An elongate tubular support structure with two sets of circumferentially spaced fingers or inserts that move radially outward under the influence of axial movement of a centrally positioned actuating member. The inserts are biased radially inward under the influence of spring members that contact each set of inserts. Movement of the centrally positioned actuating member causes one set of fingers or inserts to move radially outward into contact with the internal surface of a glass tube before the other set of inserts moves into contact with the internal surface of the glass tube.