I have an old (1978) 30 foot aluminum dump trailer ("gravel bucket)
that is in need of some welding TLC.
It is shot through with fatigue cracking. While I do not remember the
exact alloy, it is one of the "imminently weldable" flavors.
Most of the fatigue cracks are in the sides. Therefore, all welding to
these cracks will be vertical.
Additionally, some of the reinforcing gussets welded between the bottom
of the floor and the aluminum cross members are either cracked or
missing. Therefore, there will be a considerable amount of overhead
An added complication is that I have no experience welding aluminum.
The only bright side to this picture is that I have a couple of
excellent machines. The first, a Miller Syncrowave 500 (625 amps of
maximum output!) has virtually all the bells and whistles. In fact I
believe it has everything EXCEPT a sequencer.
The other weapon is a Millermatic 250X with Miller spool gun.
I have been told on good authority that over the decades, especially in
dump trailers, the aluminum sucks up all kinds of contaminants, which
you cannot adequately remove by merely cleaning the metal.
Although thorough cleaning is obviously mandated, "the word on the
street" is that, to get a good weld, you have to weld a bead, grind it
out, weld it up, grind it out - repeatedly - until FINALLY the goop
will boil out and you'll finally get a good weld.
The above was communicated to me by the honcho who works for the
factory. Therefore, I trust this to be good information.
Because of this, it would seem to me that the better option would be to
TIG weld as much of the repairs as possible. My understanding is that,
especially with the pulse and other controls on the Syncrowave welders,
and provided you dial it in correctly, I should be able to sit there
and stir the puddle without burning through and glopping a big wad of
aluminum onto my boot.
Has anybody been there and done that? Obviously, I'm not gonna just
strike up either machine and produce perfect welds. As a matter of
fact I have virtually no experience (as yet) with either machine even
with steel. So the plan is to start practicing rather intensively.
What I'm hoping to get from this post is an orientation by somebody
who's actually experienced at doing out of position aluminum patch
welding with both processes - and ideally - with these very machines.
I take this opportunity to thank everybody in advance for your
If you have a great deal of repairs you might consider removing the box
from the frame. If you have a loader large enough it might be worthwile.
You could cross brace the open part of the trailer and identify all your
repair sites with a felt marker before removal. A die grinder with coarse
carbide burrs will help prepping corners and gouging out cracks. The
slivers are murder though. A facechield and gloves are mandatory.
Good quality vertical and overhead welds are doable with MIG however it
does take skill and practice. I had a friend in a shipyard who being a top
hand was asked to qualify to do repairs on 2 mm aluminum on a large
hovercraft. It took almost a week for him to get the procedures down pat
before he could move on to the job. That is not a typo... 2mm with MIG on
Gunner has an excellent point about the value of scrap.
Unfortunately, I don't have the luxury of taking that amount of time to
do an off-frame repair.
Some of the old repairs on the trailer need to be re-done. Those welds
look like bubble gum in places.
I never had thought about a pulser with a MIG. Is this a requirement
for doing vertical welds? If so, it's back to the drawing board 'cause
although the TIG machine has one the Millermatic 250X doesn't.
The best plan may be to work the trailer until it cracks into two
pieces and then scrap it. I had not thought about the scrap salvage
value of the aluminum bed. Maybe I can find a steel bed and put it on
But back to the matter at hand. I did not think welding aluminum out
of position was THAT difficult. Of course, in my mind, everything is
Randy Zimmerman wrote:
Some truckers put a 3/16 AR steel plate in the last third of the dump box
floor when the box is new.
I wouldn't go to the trouble of pulse. It is possible to weld vertical
with MIG on aluminum but it takes practice. I have talked to guys who built
new boxes welding vertical up by pulling the trigger in short bursts. The
MIG weld looks much like a TIG stack of dimes. In this case the owner of
the company liked the stack of dimes appearance and so did the truckers....
Abrasion resistant plate takes all the sliding abrasion that wears out the
floor when the load is tipped. The back end suffers most from this and
since the steel add to the weight the last third is the important part.
Also it gives the loader somewhere to drop the Big rocks. Boulders of
course are murder on an aluminum box.