Originally Posted by
joeavaerage
I don't know whether you use Fusion 360, given that its free for hobbyists and startups its a popular choice. Among the features of Fusion is that it has quite a good FEA (Finite Element Analysis) module which
is absolutely invaluable to stress test your design. You may have noticed peteeng's posts on this forum and he makes exhaustive use of FEA. He is also a professional mechanical engineer and spent much of his
career doing this, and his fluency and mastery of the method is superb. You and I are most unlikely to ever attain that fluency......however there are a number of very simple computational experiments
that can inform your thinking. For example the seat of the pants guess I made about the deflection of the aluminum extrusion you linked to......you don't have to guess, you can plug the numbers into
Fusions FEA module and you will get a good calculated estimate of the deflection.
I would invite you to do the same calculation but using heavy wall steel rectangular sections, say 100mm x 100mm x 9mm, and 200mm x 100mm x 9mm. My guess is that heavy wall steel sections
outperform aluminum extrusions by a wide margin, and as a gambling man I would wager by a factor of five. Steel is of course harder to work, it requires welding, which may be beyond your means,
likely as a result of welding to require stress relieving and post operation machining, all of which are expensive........BUT, for any given sum of money spent steel is STILL head and shoulders
ahead of any other material in terms of rigidity.
I would commend you spend some time experimenting with an FEA program like Fusion 360 with different materials and different sections, all it costs is time and brain power and will inform your design
choices. Then when you do spend your $5000AUD you will have a result to be proud of and give you satisfaction in use for years. Ill informed design choices lead to disappointment.
Craig