Twin-Carbon Arc Torch - Craftsman 113.201392 Owner's Manual

THE TWIN-CARE]ON ARC TORCH
Figure I
Work ordinarily done with a gas welding torch _spossible
with the twin-carbon arc torch connected to an A.C. welder.
The carbon-arc flame is similar to the flame of a gas weld-
ing torch in that it provides heat by radlahon, rather than
by direct arc between work and electrode This flame heat
greatly widens the scope of work possible with the arc
welder for brazing, soldering, welding of non-ferrous metals
and localized heating for bending, forging and hardening.
The arc torch (fig. t) consists of an insulated handle with
two projecting carbon electrode holders, one of which is ad-
justable to permff striking and breaking an arc at the carbon
tips. A thumb knob on the handle performs the adjustment
and operates csshut-off swltch built into the handle. There
are no valves or gauges that require fine adjustment as
with an oxyacetylene torch The same protective equipment
used for ordinary arc weldmg is used when operating the
carbon-arc torch.
A wide selection of flame heats may be hod by varying
the current and size of the carbon electrodes. Ahhough the
actual temperature of the arc remains the same for any
current setting, the volume of transferable heat increases
with an increase in amperage. However, amperages in
excessof those given below will only cause short carbon life.
1/4-in. carbons ....... 30 to 40 amperes
5/16-_n. carbons .... 40 to 65 amperes
3/8-1n. carbons ....... 65 to 90 amperes
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F_gure 2
i ELE Tn0_E
,k_e
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F;gure 3
To prepare the torch for use, connect its two cables to the
ground and electrode cables of the welding machine.
Grounding of the work _snot necessary as the operation of
the arc flame is enhrely independent With the thumb knob
on the handle in the "off" pos_tlon,insert two 3/8-inch car-
bon electrodes in the holders and clamp in place at approxi-
mately one-half their length (fig. 2) Do not clamp them
on or near the ends opposite from the arc as this will cause
overheahng of the carbons. When tightening the clamping
screws, be careful not to apply too much pressure on the
carbons, as they are very bnttle and break easily. Use only
enough pressure to hold them firmly m place, if the hps
of the carbons do not hne up with each other, an adjustment
may be made by turning the Iorlgest of the electrode holders
slightly, too much turning will loosen it, and make it neces-
sary to disassemble the torch to agaln tighten it properly.
Do not make any turning adlustments wdh the shding holder
as this would spo_l the contact tensRonin the sw_tch
To strike the arc, turn on the welding machine and set _t for
approximately 70 amperes Lower the welding helmet and
hold the torch up to silhouette it against the hght of a win-
dow. Slowly move the thumb knob forward untd contact
Lsmade between the hps of the carbons. Th_swLH start the
arc Then Jmmed_ate[y move the knob back to mcrease the
gap between the carbons. The actual d_stance can be deter-
mme_ with a httle prachce When the carbons are too close
the arc flame will have a sharp crackhng noise As the
distance between the carbons is increased, the crackhng
w_rfchange to a soft purring sound which md_cates the best
arc flame. There are two heat zones and the small tuner
zone _sby far the hottest, having an eshmated temperature
of 9000 degrees Fahrenheit (fig 3)
The shape of the flame greatly influences the way m which
it must be used For example, on beveled work the torch
should be held parallel to the groove so the flame wdl reach
the bottom (fig. 4). If held at right angles to the groove, the
flame straddles the groove and the heat w_ll not reach the
bottom (f_g 5) Filler rods, as for gas welding, must be used
on Iomts of tb_s type
The soft, bushy flc_me _s pressureless and has no tendency
to blow the mohen metal This _sa d_shnct advantc_ge when
welding thin sheet metal Jo_r_ts an hght mater_al should be
CORRECT FLAME POSITION
Frgure 4
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INcoi_RECT FLAME POSITION
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F_gure 5
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