Well, I mounted a piece of tubing on the outer bell cover of a centrifugal clutch once, kind of the hard way. No welder, no power tools at all, and the ID of the tube was about 1/16" smaller than the OD of the bell of the clutch. So, I pulled the bell off, and went to the supermarket and bought 2 lbs of dry ice, which I put in my portable cooler with the bell buried in it. While that was cooling down, I heated the tube until it was almost glowing with a propane torch, then (using vice grips and a mallet). I seated the bell inside the expanded tube... When everything had reached the same temperature, there was no moving that tube. Period, full stop. Clutch still worked fine, and the angled slots I'd cut in the other end of the tube worked fine to drive the water pump I'd made it for.