Jeff Burke wrote:

On Mon, 10 Dec 2007 03:36:36 GMT, (Richard Casady)
wrote:

On Mon, 10 Dec 2007 02:38:44 GMT, Brian Whatcott
wrote:


On Sun, 9 Dec 2007 19:16:34 -0700, "Bob La Londe"
wrote:

...

Uh-oh: you said "aluminum boat" and "MIG welder" really, really,
casually.


... I'm looking at a Hobart Ironman 250. I already got one of
those cheap ones.....
3rd - Use a clean stainless brush on all surfaces just before welding to
break up and remove the oxidation. Never use your brushes for aluminum on
ANYTHING else. Brushes are cheap insurance. USE THEM EVERYTIME even if you
brushed it yesterday.

4th - A spool gun is the way to go, but even with a push feed gun its
possible to push aluminum if you swap out the V groove feed wheel for a U
groove feed wheel....

5th - There is no 5th item

Bob La Londe

This seems like a plan to me: the story I hear quite often is that
the hot puddle will drop out given half a chance on thin stock.

A particular optical filter is said to be a big help in visualizing
the puddle's state.

THere have been at least a million aluminum airplanes produced. All
were riveted. Wonder why?


Lowest bidder?


not hardly.

Best fastner for the material.

On Mon, 10 Dec 2007 00:14:16 -0600, cavelamb himself
wrote:


THere have been at least a million aluminum airplanes produced. All
were riveted. Wonder why?


Lowest bidder?


not hardly.

Best fastener for the material.

Rivets were the best fastener for ships until they started welding
plates (then a few Liberty ships sank before the subs got 'em.)

Brian W

On Mon, 10 Dec 2007 20:48:04 GMT, Brian Whatcott
wrote:

On Mon, 10 Dec 2007 00:14:16 -0600, cavelamb himself
wrote:


THere have been at least a million aluminum airplanes produced. All
were riveted. Wonder why?


Lowest bidder?


not hardly.

Best fastener for the material.

Rivets were the best fastener for ships until they started welding
plates (then a few Liberty ships sank before the subs got 'em.)

Brian W

Most of the high strength aluminum alloys are not weldable.

See Materials specification for 2024 - one of the more commonly used
aircraft alloys:

Welding

Welding may be done by use of resistance welding or inert gas
consumable electrode arc method. However it must be noted that, in
general, welding by any means is NOT recommended for this alloy
because of the degradation of corrosion resistance that occurs as a
result of weld heat. A repeat heat treatment should be done if welded.

Bruce-in-Bangkok
(Note:remove underscores
from address for reply)

On Tue, 11 Dec 2007 16:58:38 +0700, Bruce in Bangkok
wrote:


Rivets were the best fastener for ships until they started welding
plates (then a few Liberty ships sank before the subs got 'em.)

Brian W

Most of the high strength aluminum alloys are not weldable.

See Materials specification for 2024

Bruce-in-Bangkok

I marvel that people thinking about aluminum sheet invariably think of
2024. There are stronger materials now available, but weaker
materials are often useful. But one other factor mitigating against
welding is the top coat of soft aluminum which helps the sheet resist
corrosion.

Brian W

On Tue, 11 Dec 2007 07:47:00 -0600, Brian Whatcott
wrote:

On Tue, 11 Dec 2007 16:58:38 +0700, Bruce in Bangkok
wrote:


Rivets were the best fastener for ships until they started welding
plates (then a few Liberty ships sank before the subs got 'em.)

Brian W

Most of the high strength aluminum alloys are not weldable.

See Materials specification for 2024

Bruce-in-Bangkok

I marvel that people thinking about aluminum sheet invariably think of
2024. There are stronger materials now available, but weaker
materials are often useful. But one other factor mitigating against
welding is the top coat of soft aluminum which helps the sheet resist
corrosion.

Brian W

The question was about why airplanes were riveted and I believe that
2024 is still used in the aircraft industry although I think it is all
alclad, as you say.


Bruce-in-Bangkok
(Note:remove underscores
from address for reply)

On Tue, 11 Dec 2007 16:58:38 +0700, Bruce in Bangkok
wrote:

THere have been at least a million aluminum airplanes produced. All
were riveted. Wonder why?


Lowest bidder?


not hardly.

Best fastener for the material.

Rivets were the best fastener for ships until they started welding
plates (then a few Liberty ships sank before the subs got 'em.)

Brian W

Most of the high strength aluminum alloys are not weldable.

Yes, of course. There are weldable alloys that make a very nice boat
and they are easily weldable if the plates are thick enough. Rozema in
Seattle makes a nice forty foot power boat. Yacht or oil skimmer, same
fittings and workmanship. The same good cabinet latches are on the
workboat. There are otters living under the building and you can watch
them from the breakroom.

Casady

For boatbuilding, you will want to use the 5000 and 6000 series alloys. See
Pollard's book, Boatbuilding with Aluminum
http://www.amazon.com/Boatbuilding-A.../dp/0070504261
.. NEVER use aircraft or other alloys, especially for use in salt water.

These alloys, down to about 3/16 thickness, can be welded. 1/8 is trickier,
and lighter gauge requires very specialized knowledge, experience, and
equipment, generally not appropriate for small-scale boatbuilding.


See Materials specification for 2024 - one of the more commonly used
aircraft alloys: