Part 10 (1/2)

TORCH PRACTICE

[Illustration: Figure 34--Rotary Move the tip of the welding flaes of the ht hand andin s flame touches first on one side of the crack and then on the other On large work the motion ularly as the metal unites

It is usually best to weld toward the operator rather than frooverned by circule of about 60 degrees to the surface of the work The torch handle should extend in the saure 35) and not across it, except elding very light plates

[Illustration: Figure 35--Torch Held in Line with the Break]

If the metal is 1/16 inch or less in thickness it is only necessary to circle along the crack, the h material to complete the ithout additions Heat both sides evenly until they flow together

Material thicker than the above requires the addition ofrod, this rod being held by the left hand The proper size rod for cast iron is one having a dia welded up to a one-half inch rod, which is the largest used For steel the rod should be one-half the thickness of the eneral rule, better results will be obtained by the use of sether to furnish enoughqualities

[Illustration: Figure 36--The Welding Rod Should Be Held in the Molten Metal]

The tip of the rodwelded and the flame must be so directed that the two sides of the crack and the end of the rod areis added from the rod, the sides of the crack are roove and join the two sides

Afterward, asthe crack, the flathe fla Pieces of Unequal Thickness]

Figure 37 illustrates the welding of pieces of unequal thickness

Figure 38 illustrates welding at an angle

The o by the tip of the welding flame, which has considerable force, but care must be taken not to blow melted metal on to cooler surfaces which it cannot join If, while welding, a spot appears which does not unite with the weld, itall around it to a white heat and then iure 38--Welding at an Angle]

Never stop in the middle of a weld, as it is extre work

_The Flaht proportions of each gas If there is too en, the metal will be burned or oxidized; the presence of too much acetylene carbonizes the metal; that is to say, it adds carbon and ht mixture will neither burn nor carbonize and is said to be a ”neutral”

flame The neutral flame, if of the correct size for the work, reduces the metal to a melted condition, not too fluid, and for a width about the sa welded

When ready to light the torch, after attaching the right tip or head as directed in accordance with the thickness of ulate the pressure of gases to secure the neutral flaen will have a pressure of fro to the nozzle used The acetylene will have as, the pressure should never exceed 10 pounds for the largest work, and it will usually be from 4 to 6 In low pressure systeenerator pressure It should first be seen that the hand-screws on the regulators are turned way out so that the springs are free from any tension It will do no harm if these screws are turned back until they coen and acetylene regulators

Next, open the valve froenerator, or on the acetylene tank, and carefully note whether there is any odor of escaping gas Any leakage of this gason with the work

The hand wheel controlling the oxygen cylinder valve should now be turned very slowly to the left as far as it will go, which opens the valve, and it should be borne inreleased Turn in the hand screw on the oxygen regulator until the s to the requireulator adjustment should be ulator is thus adjusted the torch cock may be closed

Open the acetylene cock on the torch and screw in on the acetylene regulator hand-screw until gas coht this flow of acetylene and adjust the regulator screw to the pressure desired, or, if there is no gauge, so that there is a good full flaenerator it will only be necessary to open the torch cock

With the acetylene burning, slowly open the oxygen cock on the torch and allow this gas to join the flaht and then blue white There will be an outer fla and from one to three inches thick Inside of this flame will be two more rather distinctly defined flames The inner one at the torch tip is very sen should be turned on until the two inner flames unite into one blue-white cone frohth to one-fourth inch in diale, clearly defined cone does not appear when the oxygen torch cock has been fully opened, turn off some of the acetylene until it does appear