On Monday, May 6, 2013 12:37:15 PM UTC-4, Danny D wrote:
But, they 'do' have to fit together, so, that's why a
3/4" to 1/2" fitting would be perfect, if I could find one.

No, it wouldn't.

That junction would be tremendously weak, and would likely break the first time you used it. It is not intended to be a structural connection.

In order to have any strength at all, the smaller tube needs to telescope INSIDE the bigger tube for some distance. It needs to be a snug slip fit or it will flop around either kink the inner tube or split the outer tube.

Try telescoping the 3/4" and 1/2" together. It's too sloppy of a fit. It will never work as-is.

If you're a machinist you could turn some bushings out of brass or steel to take up the slack, but if you were a machinist you'd have thought of that solution already.

Redneck solution involves wrapping the smaller tube with electrical or duct tape to take up the slack. Drill for a cross pin to hold the pole at a predetermined length. Multiple holes in the smaller tube to make it adjustable.