joining aluminum sheets techniques

"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote:
Jim Logajan wrote:
"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.

Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely
difficult.


What about welding it?

Might work with joining sheets to ribs, but sheets-to-sheets? Don't know
either way, actually. :-)

I never got around to experimenting with it, but I had considered trying to
use a flux of some kind (something to deal with the formation or thickening
of the oxide layer) applied between two overlapping sheets and then
applying heat using a high-temperature heat gun. Some of the heavy-duty
heat guns claim air temperatures near the melting point of some alloys of
aluminum.

Jim Logajan wrote:
"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote:
Jim Logajan wrote:
"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.
Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely
difficult.

What about welding it?

Might work with joining sheets to ribs, but sheets-to-sheets? Don't know
either way, actually. :-)

I never got around to experimenting with it, but I had considered trying to
use a flux of some kind (something to deal with the formation or thickening
of the oxide layer) applied between two overlapping sheets and then
applying heat using a high-temperature heat gun. Some of the heavy-duty
heat guns claim air temperatures near the melting point of some alloys of
aluminum.

I just tried my hand at welding aluminum this past weekend. I'm putting
a fuel tank together. Unless you have some major jigs, the sheets will
warp all to hell before you get halfway down a joint.

On 13 Mar 2007 14:47:13 -0700, "dirigible designer"
wrote:

I'm making an eight-foot study model of a personal lifting body
dirigible design of mine. I believe the ribs will be made of
fiberglass and widely-spaced for lightness. I want the skin to be
aluminum sheet.
It would be desirable to avoid installing a rib for every seam
between sheets of aluminum. So, I would like some advice on what is
the state of the art with infallible glue joints between hard aluminum
sheets.
I imagine there is no alternative to crimping the meeting edges as
is done when sewing two sheets of cloth together.
No way am I interested in rivets.

Several horse trailer manufacturers attach the outer skin with
adhesive and double sided tape.

--Andy Asberry--
------Texas-----

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.
--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478
(760) 408-9747 general and layout cell
(760) 608-1299 technical and advertising cell

www.vkss.com
www.experimentalhelo.com


"Ernest Christley" wrote in message
...
Jim Logajan wrote:
"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote:
Jim Logajan wrote:
"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.
Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely
difficult.

What about welding it?

Might work with joining sheets to ribs, but sheets-to-sheets? Don't know
either way, actually. :-)

I never got around to experimenting with it, but I had considered trying
to
use a flux of some kind (something to deal with the formation or
thickening
of the oxide layer) applied between two overlapping sheets and then
applying heat using a high-temperature heat gun. Some of the heavy-duty
heat guns claim air temperatures near the melting point of some alloys
of
aluminum.

I just tried my hand at welding aluminum this past weekend. I'm putting
a fuel tank together. Unless you have some major jigs, the sheets will
warp all to hell before you get halfway down a joint.

"Blueskies" wrote in message
t...

"Rob Turk" wrote in message
.. .
snip

I've used some 3M aluminum glue that
: is stronger than the metal itself..
:
: Rob

I would like to see what 3M product you are talking about...

Dan D.

Hi Dan,
This is 3M DP 490 Scotch Weld. We used it to bond our aluminum leading edge
to the spar on area's where we were not allowed to use pop rivets.
Rob

Thanks for all the ideas for joining aluminum sheets. I was amazed at
all the different versions of 3M epoxy there are. Should be one to
suit my needs. http://multimedia.mmm.com/mws/mediaw...Sum5COrrrr Q-
I'll be back in touch after I gather some materials and put a few
pieces together. high flight, Allen

"Rob Turk" wrote in message .. .
:
: Hi Dan,
: This is 3M DP 490 Scotch Weld. We used it to bond our aluminum leading edge
: to the spar on area's where we were not allowed to use pop rivets.
: Rob
:

Thanks!

"dirigible designer" wrote in message
oups.com...
: I'm making an eight-foot study model of a personal lifting body
: dirigible design of mine. I believe the ribs will be made of
: fiberglass and widely-spaced for lightness. I want the skin to be
: aluminum sheet.
: It would be desirable to avoid installing a rib for every seam
: between sheets of aluminum. So, I would like some advice on what is
: the state of the art with infallible glue joints between hard aluminum
: sheets.
: I imagine there is no alternative to crimping the meeting edges as
: is done when sewing two sheets of cloth together.
: No way am I interested in rivets.
:



Stir weld it...

"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

dirigible designer wrote:
Thanks for all the ideas for joining aluminum sheets. I was amazed at
all the different versions of 3M epoxy there are. Should be one to
suit my needs. http://multimedia.mmm.com/mws/mediaw...Sum5COrrrr Q-
I'll be back in touch after I gather some materials and put a few
pieces together. high flight, Allen

Bonded lap seams should be fine since the loads are certainly going to
be extremely low. You should make some sample lap joints with different
adhesives and pull test them. Grumman light singles are all bonded
aluminum joints, including skin laps, and have been going strong for 40
years since the first Yankees were produced.

Your biggest problem will be having even clamping pressure on the joints
during gluing.

Bonded metal joints are not super strong in tension; the strength is all
in the shear plane. That means the parts will peel apart fairly easily
and there should be a mechanical fastener at any corner of a skin.
There was an AD to do this on the Grummans.

John