22
The illustrations in Figure 19 show the
sequence for laying multiple pass beads into
a single V butt joint.
NOTE: WHEN USING SELF-SHIELDING
FLUX-CORE WIRE it is very important to thor-
oughly chip and brush the slag off each
completed weld bead before making anoth-
er pass or the next pass will be of poor qual-
ity.
Fillet Weld Joints. Most fillet weld joints, on
metals of moderate to heavy thickness, will
require multiple pass welds to produce a
strong joint. The illustrations in Figure 20
show the sequence of laying multiple pass
beads into a T fillet joint and a lap fillet joint.
SPECIAL WELDING METHODS
SPOT WELDING
The purpose of a spot weld is to join pieces
of metal together with a spot of weld instead
of a continuous weld bead. There are three
methods of spot welding: Burn-Through,
Punch and Fill, and Lap (see Figure 21).
Each has advantages and disadvantages
depending on the specific application as
well as personal preference.
1. The BURN-THROUGH METHOD welds
two overlapped pieces of metal together
by burning through the top piece and into
the bottom piece.
With the burn-through method, larger wire
diameters tend to work better than smaller
diameters because they have greater current
carrying capabilities allowing the arc to burn
through very quickly while leaving a minimal
amount of filler metal build up. Wire diame-
ters that tend to work best, with the burn-
through method, are 0.030 inch diameter
solid wire or 0.035 inch self-shielding flux-
corewire.
Do not use 0.023 inch diameter solid or
0.030 inch self-shielding flux-core wires
when using the burn-through method
unless the metal is VERY thin or excessive
filler metal build-up and minimal penetra-
tion is acceptable.
Always select the HIGH heat setting with the
burn-through method and tune in the wire
speed prior to making a spot weld.
2. The PUNCH AND FILL METHOD produces
a weld with the most finished appearance
of the three spot weld methods. In this
method, a hole is punched or drilled into
Figure 19. Butt Joints
Figure 20. Fillet Weld Joints
Figure 21. Spot Welding
