Originally Posted by JMcDonald  It is indeed addicting!
I can't say much now, but I definately understand your concern about the weight, especially if you will be working alot by yourself.
I will draw up some more designs later, but I gotta run now! However I assure you it would be quite simple to get that whole design to work like the other one, using little to no welding.
BTW, the unit would almost definately be stronger by using larger diameter tubing, but with thinner walls. You might not lose much weight after the increase in size, but you would gain alot in stiffness. As long as the walls were not thin enough to buckle under the weight (a drastic and quick failure). Id say you could use .12" walled tubing (roughly 1/8") instead of the .1875" tubing used in the example, and still get roughly the same strength.
*edit*
Last quick point:
In a nutshell, you could probably use the same dimensions in aluminum as he did with steel, but add the triangular supports on the side and rear of the column, and have a unit that is about 1/2-2/3 the weight, Id guess (so, 250-350lbs, rather than 500). |
Aluminum is about three times "springier" than steel.
Get a piece of length of steel, and a length of aluminum the same size.
Hang the same weight of each and see how far it deflects.
With your existing frame, see what is almost too springy now.
Aluminum parts in shear will be fine, but things that have bending loads will need attention. Like has been said. More triangles.
Youngs modulus? Learn about it here...
http://en.wikipedia.org/wiki/Youngs_modulus