Abstract: A first tube of rectangular cross section is joined to a second tube by notching the first tube on two sides to assure that the top and bottom walls of the first tube touch the rounded corner of the second tube at a central location to define a weld receiving groove and to eliminate the gap between the abutted tubes for repeatable, well defined welds. To avoid large fixtures and structural locators adjacent a weld location, a small tab is provided in the notched end of the first tube. An oversized laser-cut slot in the side of the second tube receives the tab and has one slot boundary precisely located with respect to a reference point on the second tube. The first tube is urged in the direction to force the tab against the boundary and positively locate the first tube with respect to the reference point.

Abstract: Precise and fastenerless connection of a fixture to rotatable headstock and tailstock positioners is provided by a slidably engageable ball and socket arrangement located on the headstock positioner and on one end of the fixture, and by a tapered roller located at the opposite end of the fixture which is cradled between two grooved rollers located on the tailstock positioner. The ball and socket centers the headstock end of the fixture on the rotational axis of the headstock positioner while the tapered roller and grooved rollers locate the fixture linearly as well as centrally. The overall fixture support arrangement permits misalignment of the headstock and tailstock positioners without binding of the fixture. A second slidably engageable connecting device at the headstock end assures precise rotation of the fixture in unison with the headstock positioner.

Abstract: Precise and fastenerless connection of a fixture to rotatable headstock and tailstock positioners is provided by a slidably engageable ball and socket arrangement located on the headstock positioner and on one end of the fixture, and by a tapered roller located at the opposite end of the fixture which is cradled between two grooved rollers located on the tailstock positioner. The ball and socket centers the headstock end of the fixture on the rotational axis of the headstock positioner while the tapered roller and grooved rollers locate the fixture linearly as well as centrally. The overall fixture support arrangement permits misalignment of the headstock and tailstock positioners without binding of the fixture. A second slidably engageable connecting device at the headstock end assures precise rotaton of the fixture in unison with the headstock positioner.