Arc welding

Rods are usually sold in boxes or cans of fairly large quantity, which can be a problem for home/shop use where the welding is infrequent. The coatings on arc-welding rods are very susceptible to moisture in the air, and must be stored in very dry, secure containers to remain effective. You may have seen welding filler rods in gas-welding outfits stored in simple lengths of pipe welded to the welding cart, but this is not suitable for arc rods. If you do purchase an arc machine, invest in several airtight metal containers to store the rods, even using bags of desiccant (moisture-absorbing crystals usually found in small bags packed with cameras or sensitive electronic equipment) in the cans.

There are two basic types of arc-welders, relating to the polarity of the electricity they produce, AC or DC. The DC machines are generally larger, industrial units found in production shops, where they are hard-wired in, or mounted in conjunction with an engine for truck-mounted use in mobile field welding. Most shop-type DC machines require shop-type electrical input, such as 440V or three-phase 220V, which you will not find in any standard home. They are designed to operate day in and day out without overheating, and are considered the best choice for welding really thick materials, so that is why we see DC arc machines in use building bridges, buildings, ships, etc. There are a few small DC machines for home use, but they have limited amperage and should be used on lighter materials. There are even combination AC/DC machines, but these are usually expensive shop machines.

By far, the most basic and practical home/shop arc-welder is an AC machine often called a "buzz-box" because of the sound it makes when you are welding. This is the least expensive single welding system you can buy, with a good name-brand buzz-box costing about the same as a set of oxy-acetylene torches. However, the arc machine comes with rods and everything you need, while the gas setup also requires filled cylinders which make a ready-to-weld gas setup about twice as expensive as a basic arc box.

The wiring you have in your house or shop will be a factor in choosing the type of equipment best suited for your purposes. To use an arc machine, you'll need 220V availability. If you already have an electric stove in your house (or the house had at least been wired for this) or an electric clothes dryer, you're probably in good shape because many electric stoves and dryers use 220V current. However, unless your dryer outlet is already out in your garage, you may have to have a qualified electrician run this 220V power out to where you'll be doing your welding. If you don't already have a 220V outlet, the cost of running new service to your garage may double the total expense of setting up to do arc-welding at home. Also, welders do not just plug into the same outlet as your appliances. The welder has a different arrangement of prongs on its plug, and an adapter is required to plug into a 220V appliance outlet. The outlet you use should also have a good 20-30-amp circuit breaker as well. Note that there are some small buzzboxes that plug into ordinary household 110V power, but they aren't recommended for anything but light and occasional work. A stick-welder is relatively easy to use. Unlike gas welding, where you have to operate the torch with one hand while feeding the filler rod with the other hand, there is only one piece to control with arc-welding, the rod-holder. However, the rod starts out 12 to 14 inches long but is used up continually (gets shorter) as you weld, making it tough to maintain an exact distance of rod to workpiece, which is critical to a good arc weld. With the rod too close, you burn holes in the metal, and too far away you can lose the arc entirely and have to restart. So the trick in arc welding is control of the tip of the rod, and, because it is always getting shorter, you have to "fine-tune" your wrist movement in the hand working the electrode-holder. For this reason, most arc-welding is done with two hands, especially when learning. Use your other hand to steady and help control your wrist action on the "working" hand. Professional weldors use arc-welding upside down, laying on their back, hanging from scaffolding, or even underwater with special equipment, but for the novice, a comfortable body and hand position is very important to making good welds.

An AC arc-welder is well-suited to working on heavier steel materials, from 1/8-inch to 1/2-inch thick, but is difficult to control on thinner materials. The machine will have an amperage knob, with settings from 30-230 amps (depends on make and model), which you suit to the rod and the work material and thickness. Some of the more expensive shop machines have settings that go as low as 4 amps for light materials, but gas, MIG or TIG welding is- more popular today for thin metals such as most automotive work. For fabricating shop equipment, building a utility trailer, frame repairs or farm equipment maintenance, the buzzbox works fine.

To sum up the pros and cons of an AC arc-welder, the advantages include the low initial cost, easy operation (with practice), versatility (it can be used indoors or out) and it offers a high level of dependability (no moving parts) and quietness of operation. Disadvantages include: it's less practical for thinner metals, your shop may require rewiring to accommodate it, the home arc-welder usually can't be used for welding long seams all at one time, you are restricted to the limits of your power-cord length (as with any electric machine except the generator-driven type), the welds may have considerable spatter and not look as "clean" as other types if that is a consideration (such as in art projects, metal furniture design or street-rod fabricating), and there is the safety consideration of potential skin burns. Compared to gas welding, arc-welding poses more danger due to burns, not just from little spatters of hot metal, but from any skin that is exposed to the UV and infra-red rays. You can get a severe sunburn from exposure (pro weldors wear heavy leather protective clothing) and observing an arcweld in progress without a helmet on, even for just a second or two, can cause headaches and eye irritation.

The buzz-box was once the most practical home/shop welder, but increasing availability and affordability of home MIG machines in the last ten years has put up a serious challenge to that title.

One of the oldest forms of welding, arc or "stick" welding offers versatility, strength and the ability to handle big projects and thick materials. Also, introductory equipment can be purchased inexpensively. There are some rather expensive arc-welding machines, but the most common ACcurrent machines will do fine for the home/shop user doing standard projects and repairs.

If you have thoroughly read Chapter 2, you should have a good understanding of the various kinds of welding equipment and what each type is capable of. If you think the arc welder serves your needs, then this chapter will give you a basic introduction to the equipment and procedures involved. When shopping for a machine, you may see them referred to as SMAW welders, which is the technical description of the process and stands for Shielded Metal Arc Welding.

Basic-yet-rugged arc machines are available today in welding equipment stores, major nationwide stores such as Sears and Montgomery Ward (and their mail-order catalogs) and can sometimes be found at a good savings in large lumber/home supply centers that carry a lot of power tools. Most starter units are sold with a complete setup, including welding gloves, helmet, chipping hammer, sample electrodes, and a basic instruction book. Other than the consumable welding rods, there will be little else you will ever have to buy to continue arc-welding.

You can find arc machines priced from less than $200 to professional units costing several thousands, depending on the features, but most home/shop projects and farm repairs can be performed with machines at the lower-priced end of the spectrum. There are really no moving parts involved in the machinery, and most of the name-brand equipment is rugged enough to last for many years of service. The larger machines offer certain advantages for application in professional shop use only, such as higher amperage, AC/DC switching and higher duty-cycles.

The principle of arc-welding is to attach a ground cable to the workpiece, set the machine for the correct amperage based on the thickness of the material, fit a consumable electrode (welding rod) in the electrode holder, and with your helmet down strike the rod against the work to start a flow of current, the arc, that produces intense heat and light and welds your seam together. Welding thicker materials requires more heat in the form of higher amperage from the machine. The basic arc machines of interest to you generally have an amperage range of 40-225 amps. The arc process is best suited for thicker materials, but you will probably never use your machine at the higher settings. Even when welding on materials oneinch thick (which you will most likely never encounter in your home shop), or when repairing large castings, the seam isn't completed all in one big bead, it requires several passes on overlapping beads to totally join the parts. At the same time, you will probably never use your AC welder at the lowest settings. For materials thinner than 1/8- inch, there are other welding processes more suitable, such as gas, heli-arc or MIG-welding. Most of the basic welding performed with AC arc-welding machines is done at 90-125 amps, on materials from 1/8-inch to 3/8-inch and sometimes 1/2- inch.

Comparing duty cycles

What you will look for in an arc machine, therefore, is not the highest amperage it offers, but the duty-cycle at the 90-125-amp ranges you will use most often. We discussed the duty-cycle in chapter 2, but it bears repeating in brief. All electric welding machines have a duty-cycle rating, which refers to how long they can weld at a specific output without overheating. The duty cycle is described as a percentage. If a machine has a 100% duty cycle, it means that it can be operated virtually all day, except to stop when you change electrodes. The percentage is actually based on a ten-minute period as a test, meaning that if the duty-cycle was 50%, the machine could be used for five minutes out of ten. You could weld nonstop for five minutes and then "rest" the machine for five before starting again.

The duty-cycle rating confuses most first-time buyers, because different companies may take their published ratings from different amperage settings. The higher the amperage you weld at (for thicker material), the less the duty cycle will be. Obviously, the machine will overheat quicker at the higher amperages. On every machine's range of amperages, there is probably a point where the duty cycle is 100%. A specific machine may have a 50% duty cycle at its highest setting, yet have a 100% rating at the mid-range settings you will use most. It's important when shopping for a welder to find out what the ratings are for the high range and the mid-range. In the larger professional machines designed for welding shops and production-line work, the duty cycle must be close to 100% for any situation, and thus these machines have to be built with much more expensive components and reserve capacity.

Some of the duty-cycle rating comparisons may be academic for the average home/shop user. If the only long seams you weld are on thin materials at lower heat settings, most machines will be fine for your purposes, and there is no reason to spend many times more for the machine to get a higher duty rating. In a typical home/farm project, say where you are welding together steel tubing to make a utility trailer, the setup of the work takes half or more of your time anyway. Each welded joint between pieces of tubing may only take one or two minutes of actual welding, and then it may take you four minutes or more longer to set up clamps on the next joint or flip the work over before you're ready to make another weld. The point is that, in this example, a welding machine with a 40% duty-cycle at the amperage you were using would be perfectly adequate for the job. You wouldn't find yourself being slowed down on the job because you had to weld and then wait for the machine to "catch up." However, there is something to be said for having some duty-cycle "cushion," and if you were considering two machines in the same price range and featured similarly, you would take the one with a higher duty-cycle at the heat you would most often use it. Generally, the machine with the higher duty-cycle at a mid-point amperage will also have higher ratings at other settings.

AC, DC or both?

Most of the basic machines in stick welding are AC-powered. For those readers who may have taken electricity for granted since highschool physics classes, AC refers to alternating current, which is what we have in our houses, businesses, and power lines. The DC designation refers to direct current, for which the most common daily usage is in the 12-volt systems in our cars. When electricity was first being used in the 1890s, Thomas Edison, for all his genius in other scientific regards, was insistent on DC current being the standard for home lighting and any other usage. Unfortunately, DC current isn't practical to send any long distance through wires, and with DC every neighborhood would have to have their own power plant. The brilliant Nikola Tesla (the true inventor of the radio and many other breakthroughs) developed the alternating-current system and licensed it to Westinghouse, which became a giant corporation when AC was accepted as the world standard (AC could be sent hundreds of miles along power lines).

How AC "alternates" is by traveling in a wave, alternating in polarity up and down in a repeating cycle. Most electricity in the US alternates at a rate of 60 cycles-per-second. What all of this means to arc-welding is that the less-expensive arc-welding machines are AC-only. The AC welder is very good at producing less welding spatter, at welding heavy plates with large electrodes, requires less electricity to run and usually has less maintenance expense than bigger machines. They take the standard line current, which is high voltage but low in amperage and reduce it through a transformer to a lowvoltage/ high amperage current for welding.

The only drawback to AC arc-welding is that the constant switching of polarity can make for tiny inconsistencies in the weld bead, imperfections you and I would never notice, but something that could be critical in an oil field pipe line, high-rise-building framework or a nuclear reactor. For this reason, most professional arc welders are DC, which produces a much smoother weld, a more stable arc and there is a wider selection of special electrodes (rods) for the DC-type professional arc welder. The AC-only machines are generally used strictly for joining ferrous metals, but the DC machines can also be used for stainless-steel and for hard-surfacing industrial parts. In addition to the two current-specific types of arc welders, there are also combination AC/DC machines, which usually have a rectifier added to a basic AC machine. Another factor separating the larger professional machines in terms of flexibility is the choice of polarity, and the option of a TIG torch setup. In the DC mode of operation, the operator of some machines can choose between negative or positive polarity, depending on the type of metal he is welding and the rod he is using. Most DC welding is done with reverse polarity, meaning that the rod is positive, and the work clamp is negative. This method keeps the rod very hot and makes for smooth welds and improved out-of-position work (anything other than flat on your welding table). This is not of concern in using AC machines because the nature of the current is switching polarity 60 times a second anyway. Many of the professional machines are versatile power supplies that can perform arc welding, MIG-welding (with the addition of a motorized wire-feeding attachment), or TIG-welding with an optional torch and foot control (see illustrations).

welding/fabricating shops, but most shops today don't perform much arc welding, using their power supplies mostly for TIG welding, and using a separate machine for most wire-feed requirements. The arc-welding arena in professional welding is usually in industrial jobs or construction, pipelines, etc.

Not to confuse you any further about electricity, but the larger professional machines are often available for several types of input. The most basic machines, home or shop, require 220V, and industrial units may be set up for 440V or more, and there are different phases as well. The type of current we have in most homes is called singlephase. The larger professional arc welders are made in three-phase configuration, which simply means that there are three identical inputs spaced 120 electrical degrees apart. The waves in these inputs overlap, so that voltage never falls completely to zero, making for smoother welds. Many industrial shops have big motors on lathes, mills and other machinery that run on three-phase power, which is smoother and cheaper to operate on large equipment. We will not find three-phase power at home, and some expensive equipment is required to set up a building for industrial threephase power.

Rewiring for an arc welder

Except for a few small, household-current machines capable of 100 amps or less, even the most basic AC arc welders require 220V input. Depending on the present wiring of your house, this may require an additional expense in rewiring to accommodate the welder, a factor to take into consideration when choosing the right system for you. Some homes already have a 220V outlet for hooking up an electric clothes dryer or stove (the most common household appliances to run on this voltage), but this outlet may not be where you need to weld. If your washer/dryer setup is in the garage, you're ahead of the game, and rewiring may not be necessary. Likewise, if you plan to do most of your welding in the kitchen, then your case is simplified. If you have to run a new circuit in your house to put 220V where you need it for the arc welder, put it on it's own separate circuit with a 30-amp circuit-breaker. The kind of current you may be drawing when welding thick material may blow a standard 15 or 20-amp household breaker. Call a few electricians before you buy an arc welder. Tell them what size electrical box you have (how many amps), how many open spaces there are for new circuits, and how far a new 220V circuit would have to be run to get an outlet in your proposed welding area. They should be able to give you a rough estimate of the rewiring costs. It may cost as much or more than the welder itself, and may ultimately influence what kind of welding machine you finally purchase. Even if you do have an existing 220V outlet you can use, you'll be rudely surprised when you find the welder can't be plugged in, at least not directly. The arrangement of prongs on the welder's power cable is slightly different than the layout of the typical 220V home appliance plug. You can make or purchase an adapter, or have the electrician install an outlet box in your welding area that matches the kind of plug on your arc welder (see illustration). Before plugging a new stick welder into a household 220V outlet with an adapter, you should have the system checked to be sure the wire gauge and circuit-breaker are up to the task of handling a welding machine.

The arc process

All electrical-welding processes use the flow of electricity to create heat. The power flows from the torch or electrode to the work, which is grounded to the source at the machine. In arc welding, the consumable electrode or rod makes the connection that creates the arc to the piece being welded. The welding rod is a metal rod coated with a hard flux material. As the arc is created when the tip of the metal comes to the workpiece, the heat generated at the bead is 6000° F or more, which melts both the parent metal and the filler rod, while simultaneously vaporizing the flux coating to create a gas shield around the bead, protecting the solidifying weld from contamination by gasses in the air (see illustrations). The flux actually re-solidifies on top of the bead as a hard coating of flux and slag, and when you look at a completed bead, you'll see a dome of ceramic-like material over the weld. At this point, the weld doesn't look very impressive, but when you remove the slag with a chipping hammer, a beautiful, clean bead is revealed (see illustrations). Depending on the type of rod and amperage used, there may also be some spatter (tiny beads of metal) stuck alongside the bead. Most of these beads will come off with stiff application of a wire brush, and more stubborn ones can be removed with the chipping hammer or a chisel. Making your first passes with the AC stick welder will be relatively easy, although really good passes will require considerable practice. The instruction book that comes with your welder will specify the right rods to use for various materials, and the amperage to set for different thicknesses of ferrous metal. The rest of the technique is finding the most comfortable position for your electrodeholder hand, and maintaining the proper arc distance and travel speed to make good joints.

Safety considerations

With every method of welding, safety is of paramount consideration, but each type has precautions that apply to that type of equipment in particular. In all forms of electric welding, including arc welding, high-amperage electrical current is the primary hazard. All of your cables, plugs and leads should be inspected regularly for any signs of defects. Even dirt or paint overspray on connections can cause arcing and poor welds. Water, of course, is a good conductor of electricity, and therefore should be avoided in the work area. Your clothing, equipment and especially the floor must be kept dry to avoid the possibility of electrical shock. Rubber-soled shoes are recommended, but athletic shoes (non-leather) are not. Most experts will tell you not to wear metal jewelry such as watchbands, rings, bracelets, necklaces or belt buckles when welding. If electricwelder power comes into contact with metal articles you are wearing, they can become instantly hot to the point of melting, or can cause electric shock. Of the electric welding methods, arc welding requires the most protection of your face and body during welding. The intensity of the arc produces strong UV and infrared radiation. Any skin exposed during the welding process can become burned, in severity ranging from mild sunburn to serious burns, with the symptoms not appearing until eight hours after the exposure. Leave the top button unbuttoned on your shift and you'll have a nasty V-shaped burn on your neck after only a short while arc-welding. Likewise, wear fire-resistant, long-sleeved shirts, and keep your sleeves rolled down at all times. Keep these shirts just for welding, and tear off the pockets if they have any, or keep them empty and buttoned. An experienced weldor friend of ours was recently burned painfully when welding overhead with just a shop shirt on — a hot bead of spatter went right into his shirt pocket and burned into his chest. Without the pockets, there's a chance the bead will roll off onto the floor rather than stay in one spot on your shirt. For this same reason, your pants should be kept uncuffed, and never tucked into your boots.

If you are going to be doing arc-welding often, we'd recommend you invest in some leather safety clothing, like jackets, vests or pull-on sleeves that go over your regular shirt. Arc-welding is prone to more spattering than other types of welding, and these leather weldor's clothes are highly resistant to arc spatter.

Probably your most sensitive and fragile body parts exposed to welding dangers are your eyes. Even the tiniest bit of spatter in an unprotected eye can have truly long-lasting negative effects. Always wear a full-coverage safety helmet when welding, preferably with a leather flap at the bottom- front that protects your neck area. Especially when welding overhead, like underneath a vehicle, wear a cloth cap backwards ( bill to back) to cover your hair and the back of your neck. Your helmet should be equipped with the proper safety lens for the type of welding you are doing, or your eyes could receive overexposure of UV and infrared rays in a very short time. Never observe anyone else doing arc-welding unless you are wearing proper eye protection, and make sure that when you are welding that there is no one observing you who could be hurt by watching, particularly children. Watching too much arc will not show immediate effects, but later the affected eyes will be sore, and with a sensation almost like having lots of sand in your eyes. If you do not yet have your own welder, but want to watch someone else work, get your own helmet to observe through. If you do have a welder, you may want to keep a spare helmet around in case someone wants to observe your welding prowess. Your eyes can be permanently damaged by overexposure to arc rays, but they must also be protected when working around most shop equipment, such as grinders, mills, drills and sanders, all equipment that may be involved in your welding project. Keep several pair of good safety glasses around your shop, the kind that have protection all the way around the sides. After arc-welding, you will also want to wear these safety glasses when chipping slag from your welds. The little fragments that break off are like glass. Always keep a very complete first-aid kit accessible in your work area in case of accidents.

A particular hazard with arc welding is the presence of fumes. When the electrode is consumed, the flux is vaporized, creating the shielding gasses that protect the weld from contamination during formation. Depending on the metal being welded, other gasses may be released as the metal is melted. Most welding gasses are colorless, odorless, tasteless and inert, but this is not to imply that they are harmless. Any of the common welding gasses can displace oxygen, and when you are breathing in air that contains less than 18% oxygen, you may experience dizziness, or even lose consciousness. For this reason, arc welding, or any welding process, should be performed only where there is adequate ventilation. In the case of arc welding, there is less chance of the shielding gasses being blown away and causing a bad weld, so if you find yourself welding in one spot too long, or in a confined area, you can use a household fan somewhere in your work area to maintain air circulation.

Beginning arc welding

If you have already read the previous chapter on gas welding, what you will have learned in practicing that mode will help you greatly in learning all other forms of welding, including arc. Stick (arc) welding is easier in some ways than gas-torch welding, and more difficult in others. Practice and more practice will put you on the road to good welding in any mode.

What you will find different at first about arc welding is that you only need one hand. The electrode holder and its electrode or rod is it, other than the ground clamp, which should be clamped to your workpiece or your steel welding table. The rod is both the source of filler metal and the shielding gasses, which are generated when the flux covering is vaporized. Have some scrap steel handy and some 1/8-inch rods. There are a great many specialized rods, but one of the most common is an E-6011, which is one of the easier rods to start and maintain an arc with. Although the arc process only involves the one hand-held tool, you may find that the 14-inch-long rods put your hand a much further distance from the weld area than the other welding processes. One end of the rod is bare of any flux coating for about an inch, this is the end you put in the electrode holder. It's a good idea to practice the arc "setup" without turning on the welding machine. Just situate yourself comfortably in relation to the work, and practice holding the electrode 1/4-inch away from your work joint or seam area, following the proposed seam while slightly weaving the electrode tip side to side as you travel along. This will give a feel for what is required in terms of coordination. Now if you're ready, set the machine for the right amperage for the thickness of your scrap steel, say 1/4-inch steel plates, or perhaps slightly hotter than the instructions recommend to make it easier to learn the starting procedure. One drawback of the arc-welding process is getting the arc started. You can't just flip down your helmet or lens and stab the rod against the work.

The starting procedure has been described as similar to striking a match, in which you draw the rod tip across the area you plan to start the bead. At some point in your "scratch" the rod will momentarily contact the work and the arc will start, but the rod must continue moving. Arc welding is essentially a process of creating a short-circuit across the rod and the work, and it can only be started by a momentary contact of the two. Once started, this short-circuit heats the air around the weld and ionizes it to the point where the air conducts electricity and continues the arc without actual metal-to-metal contact. As soon as the arc starts, the rod tip must be pulled back to the suggested tip-to-work distance. All of this sounds tedious and difficult, but you will pick the technique up in the first half-hour of practice.

If you touch the rod to the surface for more than a split second, it may stick firmly, in which case the rod can get red-hot for its whole length in a very short span of time. As soon as you feel the rod stick to the surface, squeeze the clamp on your electrode holder to release the rod, which is the only way to stop the rod from melting. The hot rod will stay stuck to your work. You can take it off with some pliers, but when it is really hot, don't try snapping it off with your gloves, it may burn right through the leather. Let that rod cool off and start another rod until your have mastered the arc-starting process. When you are more experienced, you'll react quickly enough to a stuck rod that you can simply break the connection immediately by twisting the electrode holder and rod side to side. Another method of arc starting favored by some weldors is a "tapping" style, in which you quickly tap the electrode tip to the work to start the arc, not in a "pressing" action, but in a short in-and-out jerk that makes contact at the bottom of the tip's travel toward the work.

Once you understand the starting process, the tip to work distance is next. When the arc starts, you must pull the rod back for a second to make a relativelylong arc (about twice the thickness of the electrode you are using) as a way of inducing some preheat into the metal, then immediately drop the rod closer, to about one rod-thickness away from the work. Keep the rod moving along the seam, and move the rod side-to-side slightly as you travel. Some weldors use a movement like a series of tiny, overlapping ovals, others a zigzag or even a "weaving" pattern. Stay in one place too long or with the rod tip too close to the work, and you'll melt a hole in your work; also, if you pull the rod back too far, you can lose the arc process and have to restart. On small seams in thin materials, you won't need to weave the rod much. When joining thick materials, the joint is usually Vee'd or beveled, and a straight pass is made along the bottom of the joint, followed by one or more passes where the oscillation or weaving of the tip spreads the bead circles out larger in the wider gap at the top of the bevel. 4-9

Haynes Welding Manual

4.16 The electrode is usually held more or less perpendicular to the welding surface to start the arc, then laid back to continue the bead. Some weldors prefer a forehand technique, others a backhand direction, such as here. The rod should be more or less vertical when the arc is struck initially, where it can really preheat the metal, but should be angled forward (in the direction of travel) 20-30 degrees as you make your pass, i.e. you hold the electrode holder somewhat ahead of the puddle, with the rod 20-30 degrees from vertical (see illustration). Try making some straight passes along a flat, horizontal plate, until you get the hang of running a bead. Run a straight bead with the puddles being about twice the diameter of the rod you are using. While you are welding, it is important to remember not to watch the arc, but rather focus on the puddle you are leaving behind it. The shape, size and crown of the puddle are the keys to determine how you are doing.

When you have the travel speed, amperage and rod-towork distance correct, you'll find out why they used to call an AC arc welder a "buzz box," because you'll get a very satisfying sound, which is a steady, crisp noise something like bacon frying. This sound your welder makes, and the way the bead looks will tell you much about your progress. If you have the arc gap too large, you'll have uneven puddling, a bead that is too wide, and the sound will be uneven. Such a weld will have more than normal spatter. On the other hand, if you have the rod tip too close, it may stick to the work, the bead will be high but not very wide and the sound will be softer.

One of the hard parts to learn here compared to gas welding is that the part you are holding, the electrode holder, must continually be brought closer to the work as the rod gets shorter, while in gas welding the torch stays the same distance from the welding. The hand-eye coordination you must learn involves keeping the tip the right distance from the work, the rod at the right angle, the correct speed of travel, and compensating for the shortening of the rod. Speaking of electrode length, when the rod gets fairly short, it's best to stop and then re-start with a new rod. When the electrodes are too short, a lot of extra heat travels to the electrode holder and your gloved hand.

The speed you travel is almost as important as the rod-to-work distance. If you travel too fast, the resulting bead will be too narrow, and you may not get 100% penetration. If you proceed too slowly, you'll wind up with a large bead, and you may induce excessive heat into the workpiece. After you have practiced speed and arc-to-work distance, practice stopping and starting a bead. In real-world welding, you will encounter seams that take several sticks to complete, but you want the completed weld to look continuous even if it wasn't. To stop a bead, when you have to change electrodes for instance, just pull the rod back up quickly to break the arc. Any time you stop arc welding, you must chip the slag away from the place you last stopped, before continuing with a new rod. When you pick-up again with the new rod, start about 1/2-inch ahead of where the last puddle was and re-strike your arc and proceed. The arc will melt the original "last puddle" and continue the bead without any apparent interruption. This will take some practice. If you have seen professionally-welded seams, they look like they were applied by a continuously-operating machine, so integrated are the stops and starts, and that's what you are shooting for.

Types of joints

After you are experienced at making straight beads on plates lying flat in front of you, begin to practice on joints between two pieces. The simplest to learn on are butt joints. If the material is 1/4-inch or thicker, you should bevel the edges of both parts before welding. As with any parts to be welded, either ferrous or nonferrous, cleanliness of the work is very important to making a sound weld, so grind the pieces to be joined not just on the bevel, but at least 1/2-inch on either side of the joint, so that impurities don't contaminate the weld. Most seams are started by tacking the parts together at either end and perhaps several places along the way, depending on how long the seam is. Because of the growth of the parts from the heat of welding, you may need to "build-in" a gap between them during the tacking phase. Some weldors place a small piece of bare copper wire between the two parts, tack one end, and then move the wire "spacer" to where the next tack will be, continuing so that the two parts are tacked slightly apart from each other with an even gap. As you weld up the seam, the parts will "grow" together. Whenever we mention tack-welding in conjunction with arc welding, remember that the slag must be chipped and wire-brushed away from the tacks before you "connect the dots" with continuous welds.

Depending on the thickness of the material you are working on, you may make a two-pass weld, one on the top and one on the bottom. This would only be feasible on plates, not on pipe or tubing, but makes for a very strong joint, and the opposing forces of distortion may keep the parts flatter than if you made only one large pass on one side. Looking at an end view of the plates, the first pass should go into the joint a little more than halfway, then the second weld on the other side should bite into that first bead for a completely- welded joint. Usually, such joints do not require as high an amperage setting on the welder as for making a single-pass weld.

One of the common uses of arc-welding equipment is in farming and ranching, where the equipment being repaired is usually too large to bring into the shop. That means that most welding that requires a bottle of shielding gas may be too susceptible to wind to be effective, and the arc-welding process is advantageous here. Also, most farm equipment is rather heavy, with large components, and arc welding's ability to fill large breaks, weld castings, and deposit large quantities of filler metal if needed makes arc a good choice. The visual beauty of the welds is seldom a factor in agricultural repairs: it's getting the equipment back into service that counts. Building up of worn agricultural parts is a common task in which the weldor makes repeated beads right next to each other to literally build a new and higher surface on the part. The work is tedious, but necessary.

Generally, you make the first pass in normal welding mode, then make succeeding passes with the electrode held at a slight side angle to the work. Remember than when arc welding, the hot filler metal is virtually sprayed off the end of the rod like a spray gun, and where you aim the rod is where the metal will be deposited. The slight side angle allows the succeeding passes to bite slightly into the previous bead. Alternate the direction of the beads and overlap them about one-third of the bead width. There are even special rods made that deposit a hard-facing on metal. These can be used to renew or create a hard cutting edge on a part, which can be later ground or filed to an edge that will stay sharper longer than the parent metal. When making any kind of 'buildup" welds, each bead must be chipped clean before you begin the next pass, or slag and impurities could be trapped by the next bead. Also, when you are building up a part, rather than fusing a seam as in regular welding, you can run the bead much wider than we have suggested so far. The idea here is not to fuse two parts but to deposit as much metal as possible onto the surface. In these cases, you can "weave" the rod tip back and forth in a zigzag or other pattern to make a wider bead.

You will find that "out-of-position" welds, welds that are not made with the parts lying flat in front of you on the welding table, are the toughest to learn. Corner joints, vertical seams and overhead seams offer increasing levels of challenge. Corner joints are commonly found when joining two plates where one plate is perpendicular to the other, like a T. The electrode should be at a 45° angle between the two parts, so that equal heat and filler metal is directed onto both pieces. In some cases, you may find you have to place the arc such that it puts more heat on the bottom plate (which is dissipating more heat from the joint) while aiming the electrode "spray" more at the upper plate to avoid "undercutting", which is when you see a slight crevice along one or both edges of a welded joint after you chip the slag away.

If you are joining heavy plates, the fillet weld may take three passes, in which case the first bead is put right into the corner, then a second pass is made alongside that one with the electrode aimed to "spray" slightly more toward the side between this bead and the corner's edge, and the third pass is aimed to the opposite side of the center (see illustrations). If, on the other hand, you are welding a thick plate to a thinner one, then favor the angle of the electrode towards the heavier plate to give it more heat. In practicing such welds, it may be advantageous to use plates that are only an inch or two by six inches. This will make for less work when cutting a cross-section through them afterwards to examine your weld for penetration and lack of voids or impurities, especially if you have to hand-hacksaw through them.

While basic, flat butt joints are most common in typical home/shop projects, the Tee or fillet joint and the lap joint make up the majority of welds in industry and construction. The lap joint, where one plate lays on top of another, is approached much like the Tee joint, with the electrode angle at about 45°, aimed at the inside corner where the two plates meet. If they are different thicknesses, then the electrode may need to be aimed to give more heat to the heavier piece. Another difference between industry and home projects is that you will seldom encounter any joint that requires more than one pass to complete in a home/shop project. The use of really thick plates just isn't that common in automotive, arts and crafts or making shop equipment, with the possible exception of building an engine stand, which might have a half-inch plate welded to a tube for the part the engine-holding arms attach to. This is one reason that arc-welding isn't that common anymore as a home/shop tool. Other methods seem better suited to the thinner materials encountered in hobby projects, though farm equipment repair does sometimes require the large-scale abilities of an arc welder.

Choosing electrodes

Your home AC arc-welder will probably come with an assortment of basic welding rods to practice with. After that you'll have to shop at your local welding supply or order from a catalog, and you should have a good idea by then of what type and thicknesses of metals you'll be working on, and thus what size and type of rods to use. Your local supplier should be able to give you good advice on what best suits your purposes. As you read or talk with other people about arcwelding, you may hear the rods termed any of the following: stinger, rod, electrode or stick. They all mean the same thing. While there is a confusing array of arc-welding electrodes on the market, the bulk of them are specifically designed for industrial and other specialty usage, and you will never have a call for them. There are perhaps only a half dozen rods that would cover your needs. Rods differ in the type and diameter the central metal wire is made of, and in the thickness and composition of the coating of flux as well. In actual use, the flux burns away at a slower rate than the rod inside, which makes for a sort of "collar" around the tip of the rod, further shielding the weld process and helping concentrate and direct the "spray" of metal coming off the wire (see illustration).

Many of the hundreds of special-purpose arc rods are designed strictly for the professional DC welder, so you won't have to worry about those if you're using a typical 220V home AC welder. For your needs, there are perhaps three types you will use the most. Of these, E-6011 is the designation for what is the most commonly-used electrode. It is one of the easiest for a beginner to master, can be used on AC or DC, in virtually all positions of welding, and can be used in situations where the parent metal hasn't been prepared spotlessly. It's main drawback is that it produces a lot of spatter. Where the appearance of the weld is less important than the ability to make a strong joint on rough or dirty materials, such as in farm equipment repairs, this is a good choice. After practicing with this one, you may want to move on to more "sophisticated" electrodes. The E-6013 rod works great in many situations, and, although it requires better surface preparation and cleaning than the 6011 rod, it will produce much better looking welds, is suitable for a variety of positions and handles metals up to 3/16-inch thickness with most home-type buzz-boxes. It can be used for lots of projects like building shop equipment, and there are even variations on this rod from different manufacturers that are specifically for sheet-metal work, in sizes down to 1/16-inch. When the size of a welding rod is mentioned, it refers only to the diameter of the wire inside. Obviously, the flux coating makes the rod appear much thicker, and if you need to check a rod, measure the bare end meant to go into the electrode holder.

There has been a variety of methods used in the past to identify welding rods, including numbers and color codes, but most rods you find today have both a number and code from the manufacturer, as well as a standard A.W.S. number, such as E-6013 (see illustration). These standard designations come from the American Welding Society and should be easy to find somewhere on the boxes of rod you buy. The E stands for electrode (for arc welding), the 60 part is multiplied by 1000 to give you the tensile strength of the wire (in this case, 60,000 psi), the next digit is a code for the type of position the rod is recommended for, and the last digit refers to the type and polarity of the current required. The 1 in our example in the "position" spot indicates the rod is good in all positions, a 2 would mean flat position. The last number indicates that this rod can be used with AC or DC, and on DC can be used with straight or reverse polarity, though straight polarity is seldom used.

Another good rod for starting out is E-7014, which is higher in strength and produces good-looking beads. It and the E-6013 mentioned earlier require a little different arc procedure than what we have described so far. These are called "contact rods" because, instead of maintaining a basic 1/8-inch gap as you go along, you keep the tip just in contact with the parent metal, in a sense dragging the rod lightly along the seam.

A special-purpose rod used in repairing cast-iron, such as automotive blocks, cracked heads, transmission cases, and various farm equipment, is EST, although there are several brand names in the trade just for castiron rod. Most rods for this purpose have a high nickel content. Although these rods are available, it doesn't mean that cast-iron welding is easy. Any cast part should be thoroughly preheated to 400° F or better to prevent cracking after the localized heat of welding is induced into the part. Parts, depending on their size, can be heated in an oven or with a rosebud tip on an oxy-acetylene torch, using temperature indicating paints to tell when you have it evenly heated to the proper temperature. Even then, there can be cracking problems. It can be very difficult to get a cracked cast-iron part thoroughly cleaned before welding, usually requiring a deep Vee to make a good repair. Better success on cast iron may be had by welding in short strips 1/2 to 3/4-inch long, with the part cleaned and allowed to cool off in between. In automotive use, broken cast-iron exhaust manifolds are a common repair item, and the high-nickel rods can be used successfully, but a well-used exhaust manifold needs to be sandblasted inside and out beforehand to get rid of as much of the carbon baked into the pores of the casting as possible. Usually, a brand-new casting will take a much-longer-lasting weld, such as when modifying manifolds to accept turbocharger flanges. Most small cast-iron repairs are better made with brazing by an oxyacetylene torch, where much less heat is introduced, although the part should still be preheated.

Arc-welding electrodes are also marked with color codes. Usually, the flux coating itself is a different color to indicate a type, as well as markings or dabs of colors near the tip. The E-6011 has a white flux coating and a blue spot color, E-6013 is a dark tan with a brown spot, etc. Proper storage of electrodes is critical to their performance (see illustration). They are very susceptible to moisture, and must be stored in a perfectly dry environment. Once they absorb moisture, the flux coating tends to loosen and flake off, and the rod is useless. In large production operations where critical welding is done, the rods are stored in a special oven that keeps them at a constant 100° F or more to ensure that they are dry, and only enough rod that will be used in a few hours is removed at one time from the oven.

In a home/shop situation, buy only as much rod as you think you need to keep around for unexpected projects, a few pounds of each type you normally use. Keep these in either sealable metal cans or plastic bags with desiccant inside. Desiccant is a moisture-absorbing compound, the stuff we always find packed in little "teabags" with electronic components and camera equipment. You can save up these bags whenever you get a new electronic goodie. The bags can be dried out in the oven for a short while, then put into the container holding your welding rods. If you have a bigger project in mind, buy what you need for that project only, fresh from the welding supply, and don't keep any large quantities around. We have seen a variety of methods used by weldors to keep electrodes dry, including racks of custom-built metal tubes with screwcaps.