The problem is to get a square fitting onto a round tube. I started by cutting a 1 3/4" kerf down the long axis of the tube. The kerf was widened using a cut-off wheel. The tube was heated and gently tapped to close the kerf. The seam was welded to form a tapered end to the push tube. The tube is then inserted into the square tube. The square tube will be heated then formed around the tapered tube.
