Abstract: An inner bar and a sleeve thereon, slidable and rotatably mounted on the bar. Maze grooves are formed in the bar and a follower rides in the grooves. The follower is a pin, or a ball, as desired, and in the case of the ball, it is captured, or free moving, in different forms. In one form the bar is made up of sections which can be pre-positioned selectively to form different overall patterns of grooves. In one form, the parts of the device are of different colors.

Abstract: A T-nut having a lower head, and an upper shank, the shank fitting in the narrow portion of the T-slot. The head and the shank have chamfers and radiuses enabling the T-nut to be rotated in the T-slot, into active/locking position. On the shank, the radiuses dimensioned for either clearance or interference fit with the sides of the slot. In a second form, a locking washer positively locks the T-nut in active position. Also included is an arrangement of spacers and T-nuts for mounting a drill through plate on the table of the milling machine.

Abstract: A tubular main bar, internally threaded, with buttress teeth, from each end, with a stop in the middle, and an inner bar inserted in each end, having a single tooth element, spring pressed radially outwardly, forming a buttress tooth engaging the buttress teeth in the main bar. The inner bars can be pushed inwardly, but must be threaded, or turned, out. The weights are fitted on the inner bar at each end, against the end of the main bar and a locking collar interlocks with the outer end of each inner bar, and holds the weights. The outer surface of the locking collar and of the inner bar lie in a common plane, defining the end of the dumbbell. The inner bars cannot be threaded completely out of the main bar, except by special manipulation of the tooth element in the inner bar, through an inconsipicuous opening.

Abstract: A dumbbell including a bar having at each end a plurality of longitudinal grooves, of different lengths, closed at their inner ends and opening at their outer ends into a cross groove. The cross groove is defined on its outer edge by a rib at the end edge of the bar. An inlet groove opens through the end of the bar, and lets into the adjacent longitudinal groove. An inner collar slides on the bar, having a dowel pin riding in the grooves and positionable in a selected groove to accommodate a corresponding number of weights. A square headed bolt threads into the end of the bar, and the locking collar has a square hole enabling it to be slid over the bolt head, and a square socket coincident with the hole, receiving the bolt head upon turning the collar 45.degree., and the collar can then rotate the bolt.