ROAD AND WORKSHOP by Handyman

1st May 1964, Page 68

1st May 1964

Page 68

Page 68, 1st May 1964 — ROAD AND WORKSHOP by Handyman

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Arc Welding Hints—the Butt Weld in Downhand Position

THE art of making a strong, and at the same time, tidy butt weld is not quite the simple job it may seem and to rely on a sheer mass of deposit is not sufficient. First and foremost is the need to select the correct gauge electrode, and although experience will help, the following figures are a good guide for the lighter plates met in general garage work. For fin, plate use a 12 s.w.g. rod, for 5/32-in. use 10 s.w.g., for *-in. use 8 s.w.g., for fin, and above 8 or 6 s.w.g. to suit the strength needed.

Now to butt welding, and for the neat, strong, single side weld, preparation is necessary. If you are about to weld two *-in. plates of, say, 12-in, width, both edges should be bevelled at 300, giving a V at 60°. The plates should be set level, a small gap allowed as shown in Fig. 1, and tack welded in runs of in. at each end and one run in the centre.

These tacking runs should be good, otherwise the plates will move at weld

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For welding an unprepared butt joint good penetration is necessary, as both edges must be fused into the joint. Quite a lot of unprepared butt welding is seen today and it is worth a study. This form of welding calls for a higher current and care is needed to avoid untlereutting. It is also necessary to weld from both sides as full penetration cannot be expected with heavy plate. It is possible, however, to obtain special rods for this form of deep penetration. Again, a gap is required between the plates, and before starting to weld the reverse side, all slag must be carefully removed and the gap well cleaned. As the plate thickness increases, however, single side preparation is necessary and on plates above 4-in. thickness double bevelling should be made at an angle of 60°.