Flat Welding - Craftsman 113.201372 Owner's Manual

FLAT WELDING
TACK
• WELOS
Flat welding includes all types of joints in which the weld
is horizontal, and the electrode is fed down 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 on llght material should be practiced first on
scrap stock_ Use 16-gauge mild steel sheet metal (approxi=
mately 1/16-inch thick) and 5/64-1ech rods with the welder
set at approximately 30 to 50 amperes, Butt edges of metal
together and tack-weld approximately every three inches
(fig. 2)_ (Tack welds are small beads 1/4 to 3/8-1nches 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 llne directly above the edges to be joined.
If the weld burns thro.ugh in places, reduce the welding cur-
rent or increase 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 wlll 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 in the direction of the
weld to bridge the gap and give the metal in the crater a
chance to solidify (fig 3).
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
on 8-gauge metal or heavier, a 1/16 to 3/32-1nch gap
should be allowed 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 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 Agood weld should havea relnforcement slightly
more than flush with the surface (fig 6) Turn the plate
SLIGHT / /
GAP / ,
St;EEl"
METAL
k___J\
BACK-UP
STKIP
Figure 4
Figure 3
REINFORCEMEHT
Figure 6
Figure 5
Figure 7
over and weld a similar bead on the other side (fig. 7) A
higher weidlng 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 1/4-1nch
rod, the same results can be obtained with the 180 and
230-ampere machines if edges 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 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 beveled, the angle should be at 45 de-
grees (fig 10)
1-8