I spent some time doing research on the 6061 aluminum alloy specified in the plans.
Ian specifies a "-T6" temper (solutionized and artificially aged) but then some additional work can be done to the metal to improve it's characteristics before leaving the factory. The -T6511 aluminum is solutionized and artificially aged, then internal stresses are removed by stretching slightly and finally, some minor straightening takes place. If you look around you can find the "H" identifier (6061-T6511H) which is an Alcoa Special Temper. This temper indicates improved machinability and higher minimum mechanical properties than standard -T6 or -T6511. Minimum properties of 42 ksi tensile, 38 ksi yield and 10.0% elongation are guaranteed.
Anyway, I scoured the Internet and local shops for some aluminum to make the Upper Folding Struts (UFS)
The prices for these four pieces were all within the 300-500 dollar range, which I thought was pretty high. I finally found a
supplier that provided a much better price, so I placed the order.
They were really quick on the email replies and answered all my questions satisfactorily.
UPS delivered these yesterday:
Aluminum 6061-T6511H
(1.25" x 2.5" x 50" or 31.75mm x 63.5mm x 1270mm)
The pieces weigh in at 7.3kg each. I'm guessing they might weigh closer to 6.5kg after machining?
