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Which type/grade of Aluminum

I realize this is probably not the right forum for this question but her goes... I am in the midst of inventing/designing a small crane/boom-like product that requires lightweight, compact construction for holding a free hanging weight of about 600LBs. I have considered some plastics (delrin, zytel, etc) and am now looking into aluminum and am not familiar with the different grades/types available. I am also looking for some ideas on profile recommendations (square tube, round, rectangular?) This product will be used outside in all weather conditions an would be subject to some dynamic forces. I'm no engineer and am hoping for some guidance.

Anyone able to help?

J.Galli
- Harrisburg, Pennsylvania, USA

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Well there is a world of choice.

It depends on the overall size a geometry of the boom you are making, but some choices are: -
Extruded 6000 or even 7000 series aluminium.
Extruded then drawn 6000 and 7000 series aluminium
Extruded magnesium 'tubing'
Cast magnesium - bike frames and automotive parts
Titanium tubing - aerospace
Even carbon fibre - now used extensively for yacht spars that must be strong and light - most high performance boats use carbon fibre (e.g., Americas Cup boats).

Best regards,

Martin Webb
- New Zealand

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My recommendation is that you consult a registered professional engineer and have that person design your device. The supporting of 600 pounds could present a safety problem for you.

There are many considerations in designing such a device, a structural engineer knows what to do in the loading and stress analysis, the local codes, and the selection of materials.

Good luck,

Arvah Lyon

Registered professional structural engineer

Arvah Lyon
- Florida