Flat Welding - Craftsman 113.201892 Owner's Manual

FLAT
TACK
Flat welding includes all types of joints in which the weld
ishorizontal, and the electrode is fed clown as in the practice
welds of previous pages. The five types of joints in figure 1
can be welded in the flat position.
Butt welds 0n light materlal should be practiced first on
scrap stock. Use 16_gauge mild steel sheet metal (approxi-
mate]y 1/16-inch thick) and 5/64-inch rods with the wetder
set at approximately 30 fo 50 amperes. Butt edges of metal
together and tack;weld approximately every three inches
(fig.::2). (Tack welds are small beads t/4 to 3i8-1nches 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.
tf the Weld burns thro_ughin places, reduce the welding cur-
rent or irlcrease the rate_of travel. Some difficulty may be
experienced in starting the arc at these low current settings.
However, once the arc is started, there will be sufficient
heat to make a sourtd weld. After laying a bead, turn the
work over and inspect the Underside which should als0 have
a sinai] uniform bea;€i_:To prevent burning through where
the edges are not butted tightly together, move the rod back
and forth with short quick Strokes in the direction of the
weld to bridge the gap and give the metaf in the crater a
chance to solidify (figL 3).
Butt welds on sheet metal lighter than 18 gauge should
not be attempted by the beginner without the use ofa
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
on 8*gauge metal or heavier, a t/t6 to 3/32-inch gap
should be atlowed between them (fig. 5). Insert a wedge or
screwdriver between the plates when tack-weldlng to main-
tain the gap, then turn the piece over, so the tack welds are
on the underside.
Use enough current to melt edges of plates to a depth Of
at least one-half their thickness. Clean off the slag and
inspect it for smoothness, penetration and height of rein-
forcement. A good weld should have a reinforcement slightly
more than flush with the_ surface (fig. 6). Turn the plate
WELDING
,=
SHEET
METAL
BACK-UP
STRIP
Figure 4
Figure 3
6-1#CH
R_KFORCEMENT
Figure 6 _ Figure 5
Figure 7
FIRSTP,ASS
V-WELD
REINFORCING
4-PASSBUTTWELD
rll
Figure 9
_45_y SINGLE-BEVEL WELl)
Figure 10
over and weld a simitar 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 29_ampere machine using 1/4-inch
rod, the same results can be obtained with smaller welders
if eages of plates are beveled (fig. 8). Metal of almost any
thickness can be welded in this manner by depositing a
number of beads, one on _op 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
beveled, the angle should be at 45 degrees (fig. 10).
I-8