Aluminium tubing for telescopic support

[irving2008]

Machine a bushing on the lathe and push it in the end of a tube to get the right size?

Could do, but all the load would be concentrated at that point and would lose some of the benefit of the combined bending resistance of the two parts together.

Sorry not being clear ( or more likely I'm not understanding the problem)
I meant glue two tubes 2.125 + 2.250 together to form a composite thicker stronger tube
and glue two tubes 2.375 + 2.500 together to form a composite thicker stronger tube.
these two thicker stronger tubes will now slide over each other.

Cheers greeny

Ah, I get you. Could simplify construction...

In the meantime, using Phill's suggestion of 25.5mm steel tubing/19mm rod I have come up with this:



Uses two tubes with cross plates welded just below top (leaving room for locking collars, not shown) and at bottom. The T-shaped foot is made of 2 bits of 3mm wall 100 x 50 bolted together with 3mm angle and flat plate joining pieces (not shown) and the tubes are bolted into the foot from the side (2 x M8 bolts each side, not shown) and the bottom cross plate bolted into the top of the foot (4 x M8 bolts, not shown).

At the top, 2 x 19mm rods are welded to a cross plate which bolts into the underside of the upper units 10mm walls using 4 x M5 bolts and also sideways through the rods into the walls of the unit using M8 bolts.

Maybe able to shorten foot once I've checked C of G of whole assembly...