Fillet Welds - Craftsman 113.201392 Owner's Manual

UNDERCUT GAS POCKET
ENT
PENETRATION
Figure 11
Figure 12
Figure 13
Run the first pass on beveled plates with a 5/32-inch rod
and Jse as high a current as you can handle to obtain a
small bead on the underside. If this is not done, insufficient
penetration will result, as shown in figure 11. Be sure to
clean each pass before laying on the next. All beads are
laid by mowng the rod in a straight line with no weaving
or side-to-slde movement. On the last or reinforcing pass,
a weaving motion must be used to obtain a wide weld that
will completely cover oreceding beads. For the beginner,
the side-to-side movement .with a slight hesitation at each
end) will produce a smooth too without undercut or overlap.
Select several practice welds of different thicknesses and
cut them into 1-1/2-1nch strips. Clamp each strip in a vise
and bend it at the weld (fig. 12). If it breaks through the
weld, study it to find the cause of failure.
Corner welds are made on light sheet metal by running
a single bead along the top, after tack-welding at three-
inch intervals to prevent warping (fig. 13). If numerous gaps
are present, a back-up strip may be used. On heavier
metal two passes may be necessary and, if the design
permits, a smaller pass can be laid on the underside.
Beveling may be used to advantage on the thicker metals.
FILLET WELDS
WELD
II
BREAKING
THE WELD
Figure 4
Figure 6
Fillet welds are used to join two pieces of metal with sidesor
edges at right angles to each other. The size of such a
weld is based on the leg length of the largest isosceles right
triangle that can be inscribed within the cross sectional
area, as shown by the dotted-llne triangle (fig. 1). The
size of a fillet weld may also be measured with a square
and ruler, subtracting 1/32-inch from all dimensions under
3/16-inch and 1/16-inch from all over 1/4-inch (fig. 2).
For example, a 1/4-inch fillet weld should measure 5/16-
inch. This will offset any inaccuracy due to the slight radius
at the toe of the weld and allow for concavity of the bead.
When cs fillet weld ]s stressed to its maximum capacity,
failure will usually occur through the throat section (fig. 3).
Therefore, the strength is determined by the throat dimen-
sion multiplied by the length of the weld. Finished welds of
this type should always be at least four times their size in
length; that is, a 1/4-inch fillet weld should never be less
than one inch long. The direction in which the load is applied
to a weld greatly affects its strength, which can be dearly
demonstrated by breaking the weJd (fig. 4). A ioint so
loaded should always be welded on both sides with fillets
equat to the plate thickness (fig. 5). If this cannot be done,
bevel the plate to assure complete penetration and position
the work at a 45*degree angle if possible.
For practice, tack-weld three pleces of scrap iron together
to form a cross (fig. 6). Use a 5/32-inch rod with high curren_
and hold it as indicated in the front and side views. Move
the rod at a steady even pace along the seam without any
slde-to-side movement and deposit one inch of weld for
each inch of rod melted. The surface contour of a good we_d
lr?