After business hours and lacking a single tube of sufficient length, we spliced our crossbar together from 1.5-inch, 0.120-wall tubing, which fit perfectly inside 1.75-inch, 0.120-wall tubing. We added strength and maximized the weld area by fishmouthing the ends of the fatter tube and by drilling holes for plug welds. These tubes are staying put. To stabilize the tubes on the table during welding, we used a pair of machinist's 1-2-3 blocks. Even if you have no intention of ever machining anything, these blocks are handy items to have around the workshop.