Beginners are often understandably tentative, touching (rather than tapping) the rod on the plate at too-shallow an angle. Come down firmly at a near-vertical angle to get the arc up and running. If the rod sticks to the work, break contact quickly by circling your hand and pulling up.
Sometimes the rod wants to stick even though you’re doing all the right things. Check its tip (pictures 1.20 A, B and C). If this is healthy, look next at the return lead and clamp (1.21). The contact patch between clamp and work must be clean for easy current flow, so grind a bright area on the work and attach your clamp there. If the return lead can’t attach directly to the bits being welded and the current has to go via a welding bench, vise or anvil, make certain there’s good contact between the work and whatever it’s resting on. A small arc and burn spot often appears at this contact point, so think about that if the job’s surface finish or appearance matters.
1.20. If sticking is a problem, look at the rod tip first. Is it like (a) or (b)? Condition a comes from heavy-handedness with a sticking rod or damp flux. To rectify, scratch the rod hard until the bare core wire is melted away. Condition (b) comes from a carelessly broken arc at the end of a previous weld; the slag has sealed over the core wire. Scratch and/or tap it hard to break the seal. Condition (c) is good; bare core wire waits inside a cup of flux, ready to establish an arc.
1.21. Free current flow is choked by a return lead clamp that’s past its sell-by date. Typical trouble spots are the thinned or frayed cable (A) and corrosion where cable and clamp come together (B). Even when the clamp is healthy, big trouble comes from poor contact between the clamp and the job (C). All affect arc striking and potentially the subsequent weld.
1.22. Still no arc? See that there’s enough current coming from the set. Here the pack suggests 80-125A for flat-welding with a 1/8" (3.25mm) rod, so 100A should give easy starting.
Photo courtesy of ESAB North America.
For maximum current flow, all cables must be in good order with no current-blocking ‘bird’s nest’ of frayed connections (1.21 a & b). New return leads and clamps are cheap, so throw out anything that’s substandard. Please don’t use the return clamp as a striking-up area; a piece of scrap is a much better bet.
Answer to 1.16. Think about sparks from welding or cutting to see the hazards. A battery on charge gives off hydrogen and oxygen gases, which can explode on contact with hot spatter. The rubber gloves and cloth at the back are likely to catch fire; the electrode holder is not in the mask and its rod tip lies perilously close to the work, risking an accidental arc. Cans of petrol, penetrating fluid and engine oil sit alongside the welding area, while the upended chainsaw will leak fuel vapor or petrol. At floor level the open waste container, cleaning rag box and open grease bucket don’t bode well; neither do the inflammable degreasant and oil-soaked sawdust.
If the arc still won’t start, check that there’s enough current dialled in on the set. But how much is enough? The rod pack gives a suggested range – aim toward the top of it for easy starting (1.22). The pack should also show the minimum open circuit voltage (OCV) needed. If the set can’t deliver this voltage, striking will be much more difficult.
BUILD
Good Technique 2:
The Four Variables
Understanding the four variables is the key to a good job. And what are they? Rod angle, speed of travel, arc length and current.
Get each one right and a strong job results. Get one or more wrong and faults appear: lack of fusion, poor penetration, slag traps and undercut – all things that make welds weak.
Current
Current has the edge in importance. If you’re short here, the terrible twins – penetration and fusion – will be lacking. Both are vital for a sound weld. Low current also makes it harder to establish an arc.
The first rule of current selection is not to believe the graduations on the welding set! You’ll soon learn to see, hear and feel how the rod is running; to monitor what’s happening at the rod tip and to alter current accordingly. Changes in welding position usually call for current adjustment too, which will be covered later.
Use the rod pack’s information to set the current initially, choosing a setting toward the upper end of the recommended range. More current means more heat, and more heat generally means easier striking, better fusion and more penetration. If the rod packet information is missing, allow 40A per 1/32" (1mm) rod diameter. On all but the highest quality work, a little too much current is better than not enough.
1.23. Fusion and penetration change as welding current goes up from too low (A) to too high (C). Setting (B) was just right. Undercut and trapped slag are results of too much heat (C, 1 and 2).
To get a feel for current setting, experiment on some scrap. Make short welds, starting from below the packet-recommended minimum and ending above the maximum. See how striking, maintaining the arc and fusion all improve as current goes up?
This is summed up in picture 1.23. If there’s not enough current (heat), weld metal just heaps on top of the underlying plate (A), leaving poor fusion and penetration. Where current is too high (C) the weld bead is wide and flat, the final crater is deep, excessive heat melts a wide track and beads of spatter go everywhere. The bead surface is also often Vee-shaped, thanks to the operator speeding up to keep fusion or burn-though under control. Where current is too high (C, 1) undercut may turn up where the bead and plate meet. This happens because as the arc passes, it melts a crater too wide for the rod to fill; and if the arc is simultaneously too long, some of the rod’s precious filler metal will also be lost as spatter. Watch out for substantial undercut, as it provides a notch from which breakage begins. Working too hot also traps slag at the weld edge and in the coarse weld bead’s surface, making it hard to chip off.
Where current is about right (1.23 B) weld metal fuses and penetrates into the parent plate – exactly what’s needed for a good weld. The bead is consistent in width and the surface ripples are U-shaped; there’s no undercut and little spatter.
For most jobs a little too much current is better than not enough. But don’t go overboard or you’ll waste rod, create undercut, risk burn-through and porosity, cover the job in spatter and increase distortion by feeding in excess heat. And as an encore the rod’s flux coating will break down, and the heat affected zone will be wider than it need be.