Why 6063, and not the more common 6061? Do you happen to have a stock of
Bicycle frames have been made out of 6061. I had an Italian Allegro aluminum
frame on my sprint bike in the late '60s. It was too flexible, but aluminum
framed bikes have come a long way since then. They generally use
larger-diameter tubes to overcome the lack of stiffness.
I don't know about motorcycle frames. Spaceframe racecars have been made out
of 6061, and the Bobsy sports-racer of the 1960s was very successful with an
aluminum spaceframe: http://sports.racer.net/chassis/bobsy/sr3_1965.htm
However, aluminum has little or no advantage over steel in a spaceframe
application. If the structure's tubes are loaded only in tension and
compression, as in a spaceframe, aluminum's properties result in a chassis
that weighs about the same, is roughly as stiff, and roughly as strong as a
steel one. But it's several times harder to weld and it costs several times
Aluminum shows its advantage in structures that are subject to bending,
rather than to tension/compression. A bicycle frame does have bending loads.
A motorcycle frame generally has some, but not always.
So you want to think carefully about why you'd use aluminum. Most engineers
who have approached it have decided it's more trouble than it's worth, with
okay thank you!
i do want to use 6061 but there aren't too many suppliers of aluminum
alloys in my country and I just found this one that sells 6063 alloy
either 6061, 7075 or 2024 alloys but then it's really difficult to
look for suppliers here.
i guess i'll have to look around some more.
Except for 6061, those other alloys will require lugs and adhesive assembly,
rather than welding. 7075 can be welded but it loses its corrosion
resistance. On 2024, you won't get a satisfactory weld, and the tubes may
crack. And the welding on 6061, or any weldable aluminum alloy, almost has
to be TIG (GTAW) when you're welding tubes.
All in all, you need a really good reason to make a tube structure out of
aluminum, rather than steel.
Some of the specialty bikes are made with specially forged or formed
flanges at each frame join point, fluxed and 'preforms' of wire solder
placed inside the lugs, clamped into a jig, and the whole frame is
brazed in one shot in an industrial oven...
But when you consider all the variables that have to be controlled
and gotcha's conquered, that's an even trickier method than TIG
welding - useful only for production shops that get lots and LOTS of
practice at it.
For a low production shop or a low-skills country, and if you insist
on using aluminum tubing: Buy excellent welding gear (Miller) and
proper safety gear and accessories, and have a few staffers sent to a
tech school and get /lots/ of hands-on practice time (buy material
they can use for practice coupons) to learn how to TIG weld properly
and well. It is an art that takes time to perfect.
--<< Bruce >>--
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