Bruce L. Bergman wrote:
John Forrest Tomlinson wrote:

The 6061 T6 is fairly cheap online (onlinemetals.com), so I might try
that and if it doesn't work I can live with it.

But I might first look around for 6063 or something more easily bent
at a big hardware store .

It's the T6 part that'll getcha - the stuff that is pre-tempered.
Beg, borrow, Garage Sale, steal or (Gasp!) buy an oxy-acetylene torch
rig to heat up the aluminum and take the temper out of it before you
bend, and you'll be good to go. If you don't, you'll see it cracking
at the bend right before your eyes.

You could use a Propane or MAPP torch, but you can't use the soot
and burn trick as easily. Might have to get the Tempstik paint marker
that changes color when it reaches the target temperature - mark the
front side and heat the back side with the torch while watching the
mark for the change.

WARNING - the temperature spread from 'annealed' to 'melted' isn't
very much on aluminum. Too much heat, and you have a shiny puddle.

The 'B' Acetylene and 50 CF Oxygen cylinders are the smallest
practical size for around the home shop, when you balance purchase
price and refill price with how much work they will do on a fill.

Forget the little "tote torches" that take the 10 cubic foot Oxygen
and 'MC' Acetylene. They work for brazing up refrigeration lines, but
the bottles are too small to do any Real Work - you can't use large
tips because there is a withdrawal rate limit on the Acetylene bottle
of 1/7 capacity per hour or you start sucking out the Acetone. And
just when the work starts getting warm, the tanks go empty.

-- Bruce --

Take a part used bar of ordinary white hand soap (a new bar is a little
too hard, you could moisten it and leave it to the next day) and streak
the surface of the aluminium. Heat from the other side with any sort of
gas torch or even a gas hob. When the soap smear goes a good brown
colour, its done and you quench it in water. If you let it go black,
you overheated it, but you've still got a little margin before it turns
into a nasty puddle.

Been there, done it with minimal tools, made up an internal sleeve to
pop rivet in place to repair a racing dinghy mast that's still in use 5
years later.
We did get the broken outer tube welded as well, but it was rather
'daubed' and didn't look like it would have carried the load alone. We
waited a month before putting it in service as we didn't have the
facilities to artificially age a long tube.


If you *can* reheat it to 350 degrees F (175 degrees C) and hold it
there for 6 hours, you'll age it most of the way back towards T6
condition. As it was annealed pretty crudely and definitely wasn't
held at the proper solution treatment temperature for the correct length
of time it isn't going to be quite as good, so you might only attain T4
equivalent but for a non-critical application it'll do fine. Dont over
heat it, better to err slightly under rather than over.

Even holding it at about 100 degrees C for about 24 hours would be
beneficial and *anyone* can arrange to do that in a water bath or steam
chest.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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