On Wed, 25 Apr 2012 20:08:13 -0500, Ignoramus18965
wrote:


Some of it would involve "Overhead" welding, operating from below the
weld.

What is the easiest way to do it correctly. These would be welds that
need to hold up when a forklift or a metal tracked vehicle drives over
that tail.

We have solid mig wire and E71T flux cored.
Thanks
i

Although, I can't see exactly what you are trying to weld from the
pictures, I would recommend stick welding with 7018. Absolutely do not
use solid MIG wire. The flux core is a much better choice if you must
use a MIG set up. It is not necessary to tip your trailer over as
others have suggested, but backing it over a garage pit would help to
give you some working room.

Joint preparation is key. You should grind a vee joint between the
plates (asumming this is a butt weld) and absolutely clean it out of
any paint, rust, or grinding debris using a knotted wire wheel.

If you have no experience running a key-hole type root pass with say
6010, I'd recommend tacking a backing strip to the weld path. Usually
a piece of cold rolled steel about 1/4" thick will do the trick.
(Grind any mill scale off of it before you use it.) You can cut this
off with careful application of an oxy-acetaline torch after the weld
is completed. Then grind the remains flat and apply a capping bead
over that side of the weld.

The root pass is also key. You must keep a very short arc length with
7018 otherwise oxygen will contaminate the weld puddle. The goal is to
lay passes that stack up evenly across the length of the weld. After
the root pass you can use weaving passes to make this stack
up.....once again remembering to keep a SHORT arc length.

Before attempting to do this on your trailer, do TEST set ups and
practice. Overhead takes practice above all else.
Dave