Craftsman 196.20569 owner manual Special Welding Methods, Three Passes TJont n Li, Three Passes

NOTE: WHEN USING SELF-SHIELDING FLUX-CORE WIRE it is very important to thoroughly chip and brush the slag off each completed weld bead before making another pass or the next pass will be of poor quality.

of a continuous weld bead. There are three methods of spot welding: Burn-Through, Punch and Fill, and Lap (see Figure 20). Each has advantages and disadvantages depending on the specific application as well as personal preference.

Figure 18. Butt Joints

Fillet Weld Joints. Most fillet weld joints, on metals of moderate to heavy thickness, will require multiple pass welds to produce a

strong joint. The illustrations in Figure 19 show the sequence of laying multiple pass beads into a T fillet joint and a lap fillet joint.

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Lap Joint Welded

I _ In Three Passes

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Figure 19. Fillet Weld Joints

SPECIAL WELDING METHODS

SPOT WELDING

The purpose of a spot weld is to join pieces of metal together with a spot of weld instead 20

PUNCH AND FILL _ LAP SPOT

BURN THROUGH

Figure 20. Spot Welding

. The BURN-THROUGH METHOD welds two overlapped pieces of metal together by burning through the top piece and into the bottom piece.

With the burn-through method, larger wire diameters tend to work better than smaller diameters because they have greater cur- rent carrying capabilities allowing the arc to burn through very quickly while leaving a minimal amount of filler metal build up. Wire diameters that tend to work best, with the burn-through method, are 0.030 inch diameter solid wire or 0.035 inch self-shielding flux-core wire.

Do not use 0.024 inch diameter solid or 0.030 inch self-shielding fiux-core wires when using the burn-through method unless the metal is VERY thin or excessive filler metal build-up and minimal penetration is acceptable.

Always select the HIGH heat setting with the burn-through method and tune in the wire speed prior to making a spot weld.

,The PUNCH AND FILL METHOD

produces a weld with the most finished appearance of the three spot weld methods. In this method, a hole is punched or drilled into the top piece of metal and the arc is directed through the hole to penetrate into the bottom piece. The puddle is allowed to fill up the hole leaving a spot weld that is smooth and flush with the surface of the top piece.