2
HOW
TO BUTT
THE most common type of join in this application is
a butt weld; two pieces are simply pushed together
to join with weld. While that’s pretty straightforward,
the two types of welding machines can be used
differently to achieve the same result.USING A MIG
THE two pieces are pushed together, but a 1mm
gap is left in the middle. This allows for when the
two pieces are pulled together from the heat,
known as weld creep. This gap also gives the
MIG wire an area to melt, connecting the two
pieces of metal together.
This join is formed from numerous tack welds
made along the panel. A good weld here requires
heat – enough to penetrate but not enough to blow
a hole – and enough wire to not melt into the tip
but not so much that it’s pushing the handpiece
away before it burns. A good tack will have a small
dimple on top.
After every few tacks, the area is cooled with
compressed air. This is best done not too close to
the panel, as a high-pressure blast on a hot weld will
cause it to become porous.
Welding tacks onto 1mm sheet and trying to keep
things cool is never going to look overly nice, but
fear not, as these will be ground off anyway. Flipping
the piece over, the penetration is okay, but lacking.
UUS INNG A T I G
THE two pieces can be fitted flush; the tighter
the better. With both sides clean, a few tack
welds are placed to hold the metal in position.
The join can now be fuse-welded from one end
to the other. A consistent metal pool that can be
‘pushed’ along the join is required here. If you flip
the piece and can still see the edges of the join,
there wasn’t enough heat. Welding in one run
will cause distortion, but that’s okay; a common
misconception is that the heat has buckled the
surrounding metal, but actually the weld is pulling
everything in around it, causing it to warp.
Using a hammer and dolly (or similar) along the
weld, the tension can be released, letting the
surrounding metal return to its original position
while flattening out the piece.