Craftsman 113.201392 Owner's Manual

THE TWIN-CARE]ON ARC TORCHFigure IWork ordinarily done with a gas welding torch _spossiblewith 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 thanby direct arc between work and electrode This flame heatgreatly widens the scope of work possible with the arcwelder for brazing, soldering, welding of non-ferrous metalsand localized heating for bending, forging and hardening.The arc torch (fig. t) consists of an insulated handle withtwo projecting carbon electrode holders, one of which is ad-justable to permff striking and breaking an arc at the carbontips. A thumb knob on the handle performs the adjustmentand operates csshut-off swltch built into the handle. Thereare no valves or gauges that require fine adjustment aswith an oxyacetylene torch The same protective equipmentused for ordinary arc weldmg is used when operating thecarbon-arc torch.A wide selection of flame heats may be hod by varyingthe current and size of the carbon electrodes. Ahhough theactual temperature of the arc remains the same for anycurrent setting, the volume of transferable heat increaseswith an increase in amperage. However, amperages inexcessof those given below will only cause short carbon life.1/4-in. carbons ....... 30 to 40 amperes5/16-_n. carbons .... 40 to 65 amperes3/8-1n. carbons ....... 65 to 90 amperesiF_gure 2i ELE Tn0_E,k_e_CF;gure 3To prepare the torch for use, connect its two cables to theground and electrode cables of the welding machine.Grounding of the work _snot necessary as the operation ofthe arc flame is enhrely independent With the thumb knobon 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 themon or near the ends opposite from the arc as this will causeoverheahng of the carbons. When tightening the clampingscrews, be careful not to apply too much pressure on thecarbons, as they are very bnttle and break easily. Use onlyenough pressure to hold them firmly m place, if the hpsof the carbons do not hne up with each other, an adjustmentmay be made by turning the Iorlgest of the electrode holdersslightly, 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 holderas this would spo_l the contact tensRonin the sw_tchTo strike the arc, turn on the welding machine and set _t forapproximately 70 amperes Lower the welding helmet andhold the torch up to silhouette it against the hght of a win-dow. Slowly move the thumb knob forward untd contactLsmade between the hps of the carbons. Th_swLH start thearc Then Jmmed_ate[y move the knob back to mcrease thegap between the carbons. The actual d_stance can be deter-mme_ with a httle prachce When the carbons are too closethe arc flame will have a sharp crackhng noise As thedistance between the carbons is increased, the crackhngw_rfchange to a soft purring sound which md_cates the bestarc flame. There are two heat zones and the small tunerzone _sby far the hottest, having an eshmated temperatureof 9000 degrees Fahrenheit (fig 3)The shape of the flame greatly influences the way m whichit must be used For example, on beveled work the torchshould be held parallel to the groove so the flame wdl reachthe bottom (fig. 4). If held at right angles to the groove, theflame straddles the groove and the heat w_ll not reach thebottom (f_g 5) Filler rods, as for gas welding, must be usedon Iomts of tb_s typeThe soft, bushy flc_me _s pressureless and has no tendencyto blow the mohen metal This _sa d_shnct advantc_ge whenwelding thin sheet metal Jo_r_tsan hght mater_al should beCORRECT FLAME POSITIONFrgure 4iINcoi_RECT FLAME POSITION\ \F_gure 5!16