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Flat welding includes all types of joints in which the weld
ishorizontal; and the electrode is fed d own as in the practice
Welds Of previous pages_ The five types of ioints in figure 1
can b_ welded in the flat position.
Butt welds
on light
material
should
be practiced
first
on
scrap Stocki Use 16-gauge
mild steel sheet meta! (approxi-
mately
t/16_inch
thick) and 5/64-inch
rods with the welder
set at approximately
30to
50 amperes.
Butt edges of metal
together
and tack-weld
approximately
every
three
inches
(fig. 2). (Tack welds are small beads
I/4
to 3/8-inches
in
length.)
Place bars of scrap iron under
ends of the work to
provide
an air space above the table.
Simply move the rod
in a straight
line directly above
the edges
to be joined.
If theweld burns thrQugh in places, reduce the welding cur-
rent or increase :the: rate of travel. Some difficulty
may be
experienced in starting the arcat these low current settings.
However, once the arc iS :started, there
will be sufficient
heat to make a sound weld. After laying a bead; turn the
work over and inspect the underside which: should also have
a small uniform bead. To prevent burning through
where
the edges are not butted tightly together, move the rod back
and forth with short quick strokes inthe
direction of the
weld to bridge the gap and glVe the metat in ithe:crater
a
chance to solidify
(fig,:3)i
Butt
welds
on sheet
metal
lighter
than
18 gauge
should
not be attempted
by
the beginner
without
the
use of a
back-up
strip
(fig.
4).
This
consists
of a bar
of copper
clamped
tightly
against
the underside
of the seam to absorb
the heat
of the arc
and
prevent
the
weld
from
burning
through.
To assure
complete
penetration
with butt
welds
an 8-gauge
metc_t or heavier,
a !/16
to 3/32-inch
gap
should
be aJlowed
between
them (fig. 5). Insert a wedge or
screwdriver
between
the plates when
tack-welding
to main-
tain the gap, then turn the piece over,
so the tack welds are
on the underside.
Use enough
current
to muff edges
of plates
to a depth
of
at feast
one-haft
their
thickness.
Clean
off the
slag and
inspect
it for smoothness,
penetration
and
height
of rein-
forcement.
A good
wetd should
have a reinforcement
slightly
more
than
flush
with
the
surface
(fig.
6).
Turn
the plate
STRIP
Figure 4
Figure
3
1/16-INCH
REIKFORCEMENT
Figure
6
p_
Figure
5
F_gure
7
-'Y-/' EOGES : :-r_ ure
f:ii!ii: ;?
GAP
_i_i :_?-ii?;,
oo
4-PASS B UTT WELO
E V-WEt_O
Figure
9
k45_p " SINGLE-BEVEL
WELD
Figure
10
over and weld
a similar
bead
on the other
side (fig. 7). A
higher
welding
current
can be used on this side as there
is
no danger
of
burning
through
and
fusion
with
the
first
bead will be assured.
Although
butt
welds
can
be made
on steel plates
up to
3!8-inch
thick,
with
a 295_ampere
machine
using
1/4-inch
rod,
the same results
can be obtained
with
smaller
welders
if edges of plates are beveled
(fig, 8). Metal
of almost
any
thickness
ca_
be welded
in this
manner
by depositing
a
number
of beads, one on top of the other
until
the groove
is completely
filled.
If the plate can be welded
from
both
sides, always
use a double
bevel (fig. 9). If only one plate is
beveted, the angle should
be at 45 degrees
(fig. 10).
To8
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