How much will it hold w/o bending?

[Artisan]

Ugh... I just looked at Metals Depot? - Buy Metal Online! Steel, Aluminum, Stainless, Brass and they call round and square both BAR

 

[the old grind]

Do you have room above for a folding truss link hinged to the right end that could function when extended and be anchored/hinged/tucked above the junction of the telescoped sections when not? This would put a tension load on the truss and a compression load on what looks like an extendable boom or something. Either of these easier force distributions would seem to increase lift(?) capacity vs the bar alone with its typical deflection. (Not much to go on ... I imagined this..):

All the easier if the bar doesn't telescope to use/store, but a 1pc truss could be 'pinned on' at full extension, too.
(I claim insomnia ... sorry if I'm 'out there')

 

[Artisan]

It is a cantilevered beam not supported at both ends.

http://www.engineeringtoolbox.com/cantilever-beams-d_1848.html

I just can't figure out how to enter the data...

 

[Sodo]

ooops made a big mistake, (formula for intertia error) but I edited it in text above. They didn't have a cantilevered beam so I did a 90" rod - and look at the middle as your cantilever.

This does seem more feasible putting 4000 lbs in the center of a 90" rod.

deflection with 2" round rod is 5.3 inches
deflection with a 2" square solid bar is 3.14 inches

I suspect 3 or 5 inches would cause 'yield' or permanent bend.

i'm working pretty fast and loose here sorry. But this is how you can do it yourself with calculators on the internet.

 

[Artisan]

Do you have room above for a folding truss link hinged to the right end that could function when extended and be anchored/hinged/tucked above the junction of the telescoping sections when not? This would put a tension load on the truss and a compression load on what looks like an extendable boom or something. Either of these easier force distributions would seem to increase lift(?) capacity a good bit vs the bar with typical deflection. (Not much to go on ... I imagined this..):
View attachment 349408
All the easier if the bar doesn't telescope to use/store, but a 1pc truss could be 'pinned on' at full extension, too.
(I claim insomnia ...)

Now THAT is thinking outside the box! HA! I will be thinking about that ! Ha!

Gotta love TBN, there are some great minds here...

 

[Egon]

Might help??

[PDF]Bending Stresses for Simple Shapes - ATC Publications Home Page
www.atcpublications.com/Sample_pages_from_FDG.pdf
Cantilever Beam, Uniform Load ... The physical properties of the material used in the design of the ... A hollow pipe, square or round, is the easiest extrusion.

Once upon a time this type of calculation was well within my limited capabilities. However, as the hair disappeared so did the limited capabilities.

 

[Xfaxman]

...to be exact, here is a little more;

That didn't work, try again.

Can you use 2x4 rectangular tubing?

 

[Farmerford]

From memory:

Section modulus of a solid square = side cubed/6; 2x2x2/6 = 1.33
Stress in outer fiber = torque in inch pounds/section modulus
section modulus x stress = torque
1.33 x 36,000 = 48,000 in pounds torque to create 36,000 pounds of stress in outer fiber
48,000 inch pounds/45 inchs = approx 1,000 pounds force at 45 inches from fixed end of 2x2 square beam cantilever to stress A36 steel to tensile strength

 

[Artisan]

That didn't work, try again.

Can you use 2x4 rectangular tubing?

That was weird, that image is now visible. It shows I actually am dealing w/ about
38" of square tube or square solid bar w/ about 7" extended off the end of that
equaling about 45" of cantilever.

I could go 2x4 if there is a 2.5 x 4.5 .25wall counterpart to slip it into then redraw ALL. err.

 

[bcp]

A folding brace is an interesting idea but it would be stronger as a triangular design.

The rectangular brace will keep the end vertical as the bar bends but won't do much to stop the bending.



Bruce