Bob La Londe wrote:

"Brian Whatcott" wrote in message
news
On Tue, 27 Nov 2007 20:54:32 -0700, "Bob La Londe"
wrote:


Anybody know of any all aluminum designs (no wood composite or sandwich)
available for sale for a shallow draft semi tunnel for river running? I
can
modify if need be, but I ain't gonna put no wood in it if I build it.
Well,
maybe for totally non structural stuff, but I doubt it.

I'm trying to talk Mrs Santa into getting me a 60% duty cycle MIG w/ spool
gun for Christmas.


--
Bob La Londe

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



There are some things about mig aluminum welding that a lot of people don't
realize...

1st - Its really hard to do a good job with a cheap welder like the 120V
20amp 10/20% duty cycle things with only two heat ranges like they sell at
Harbor Freight. I'm looking at a Hobart Ironman 250. I already got one of
those cheap ones. Figured I'ld use the push feed gun for steel and a spool
gun for aluminum so I wouldn't ever have to worry about gun/tip
contamination.

2nd - You have to burn some metal to get it dialed in just right. I got
scrap laying around from some other things I can burn up.

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. The V groove wheels shave the soft aluminum wire causing
it to plug up the feed tube and your gun.

5th - There is no 5th item.

6th - if for ANY REASON the wire doesn't feed STOP. Otherwise you will you
will have a wad of crammed up aluminum wire someplace in your rig.

7th - Practice and warm up for a few minutes on some scrap EVERYTIME before
you start on your cut pieces. (Thats a good idea on steel too.)



Tell me you have MIG welded aluminum before - that you have the right
mask screen, that you can not only stitch thick aluminum castings
together, but you have seamed sheet as well.....


Nope, I'm not super experienced, but I got a pile of scrap aircraft aluminum
to practice on. I've played some with aluminum, and I don't plan on using a
cheap rig. I've used some of the torch alloy stuff too, but its really only
suitable for small work.

I have a variable shade autodarkening mask, and I use it for everything. I
even use it for cutting. I just lighten the shade up.

And worse comes to worse... I can alway learn to install blind rivets.
LOL.



Trust me, you can't really push aluminum well enough to weld a decent
seam. I have the Ironman210, and even with the teflon liner, it balls
and birdsnests easily unless the gun is straight out from the welder.
Even then, it'll only skip once, and then you gotta get out the cutters.

Spoolgun is the way to go.

I don't care what they told you.

--
“TANSTAAFL”
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America: Ironically, the safest place to be anti-American.
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"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3