Chapter 29 Shielded Metal Arc Welding 805
Copyright Goodheart-Willcox Co., Inc.
4. Weld the 3″ × 4″ × 1/4″ steel coupon to the 10″ long
3/4″ or 1/2″ pipe handle to make the part safer
to handle and provide an excellent location for
attaching the workpiece connection. Flatten the
end of the pipe with a heavy hammer on the anvil
where it connects the coupon to simplify this step.
5. Properly attach the workpiece connection directly
to the handle. Attaching the workpiece to the table
is an indirect connection method that leads to poor
arc quality.
6. Position the coupon on the welding table. Right-
handed welders are usually most comfortable
working from left to right, and left-handed
welders are the opposite, Figure 29-51. Plan the
welding process so that movement travels from
a less comfortable position to a more comfortable
position. Leaning on stationary objects for support
further reduces unwanted movement.
7. Use a 3/32″ E6011 electrode to weld a single-pass
bead along one edge of the coupon in the fl at (1G)
position, Figure 29-52.
8. Leave the welding machine running. Remember
that the duty cycle requires a cool-down time
to protect the internal components of the power
source.
9. Thoroughly clean the bead with a chipping
hammer and a wire brush, Figure 29-53. Lightly
tap at the edge of the bead—avoid hammering
hard enough to leave marks on the surface of the
bead. Do not cool the coupon at this point. Rapid
cooling deteriorates bead quality.
10. Weld a second bead between the previous bead
and the plate. There should be a 25% to 30%
overlap on the previous bead, Figure 29-54.
Alternate the direction of travel with each
successive bead to yield a smoother surface.
11. Thoroughly clean the bead and continue welding
and cleaning until the plate is covered. It is very
important to clean welds thoroughly between
each pass.
12. Weld a second layer of beads perpendicular to and
on top of the fi rst layer, covering one-half of the
coupon.
13. Clean the welds thoroughly. At this point it is
acceptable to cool the pad prior to handing it to an
instructor.
Goodheart-Willcox Publisher
Figure 29-49. Distortion of a welding pad caused
by the contraction of cooling beads.
4"
3"
Goodheart-Willcox Publisher
Figure 29-50. Overlapping layers of beads will
cover the practice pad.
Goodheart-Willcox Publisher
Figure 29-51. Grasp the handle of the electrode
holder with the dominant hand. Use the other hand
to provide support.
Goodheart-Willcox Publisher
Figure 29-52. The first pass weld on a practice pad
is positioned very close to the long edge of the plate.