joining aluminum sheets techniques

"Stuart & Kathryn Fields" wrote in message
.. .
I welded 4 aluminum gas tanks ( I busted the first two in an incident) and
one oil tank for my Baby Belle. I don't remember having much warpage, but
I
also recall someone telling me to tack the things in a lot of places
before
finishing the seam welds. The things pressure tested to 14' of water the
first time with no pin holes. Now if that doesn't prove luck is better
than
skill I'll eat a welding rod. I also welded some aluminum beer cans
together, but they wouldn't hold mashed potatoes after I finished with
them
let alone a liquid.
--

I have welded a lot of aluminum, including successful welding of beer cans.
And I second all of Stewart’s advice. When welding .030 and up, you will
want to tack weld even as close as every two to three inches before
beginning your finishing welds. Skip welding helps as well, meaning weld
between two tacks, skip between two tacks, and weld between the next. It
will all help to avoid distortion. Also, clean, clean, clean. Scrape or buff
everything with stainless steel rotary brushes, cleaned thoroughly in
acetone or eqv. If you pick up any oil or grease anywhere, clean your
scrapers and brushes and start all over. It even helps to handle everything
with clean cotton gloves. You can leave enough oil from your bare hands to
affect the quality of your welds, unless you keep your hands washed in
acetone, which I certainly don't recommend.



As for thinner than .030 or so, good luck without good fixtures. I have seen
some soldering techniques advertised the might be very workable, but have
never tried any of them.



As for glue, I haven't tried many, but have had pretty good luck with 3M -
2216BA. I don't know how it compares to the others mentioned above, but it
has worked well for me. On a seam of .010 with a half inch overlap, I
personally think it might be workable, but haven't done it my self. And if
you plan to glue, don't for a minute underestimate the value of cleaning,
preparation and a good primer. When done correctly under aircraft
conditions, actually mixing the epoxy and gluing your seam is only about 10%
of the battle. Proper cleaning, priming and curing of the primer is actually
more critical.



Free advice, your results could easily vary.


Max