Arc Welding Basics - Page 1 of 6


Figure 1

In its most basic form, a welder is a device that melts two pieces of metal together using high amperage delivered at the end of an "electrode" (rod) into the work. Although the technology that makes this process happen is technical enough to fill hundreds of pages, I will deliver it to you in simple terms, the same way I learned it in the beginning. Like all new skills, practice will make you proficient, and welding is a skill that anyone can learn. If you have ever had the misfortune to see an electrical short, either from bad wiring, or some type of electrical equipment failure, you will have remembered the zapping sound, puff of smoke and burnt metal that usually follows. This is basically what a welder does, but in a controlled and expected manner.

The welder places a ground clamp onto one of the pieces of metal to be joined, then feeds a conductive electrode (rod) into the area or gap between the two pieces to be welded. Because the ground clamp and electrode are the two ends of a complete circuit carrying voltage and high amperage, a dead short happens at the end of the electrode, creating intense heat, melting both the electrode and surrounding area into a single fused piece.

This type of welding is called "arc welding." The rod is not actually touching the work (parts to be welded) during the welding process. It is held a small distance from the work so that a very hot arc (electrical spark) can form. This arc produces the heat to melt the metals together as shown in the photo.

If the rod is pushed directly onto the work, a "dead short" occurs, and there won't be any heat to weld the metals since no arc will form. This is a common problem when you are learning to arc weld, known as "sticking". Sticking occurs when the rod is pushed too hard into the joint to be welded, and causes the rod to stick to the work.

An arc welding rod is a thin metal rod coated in a material called "flux." This material is melted as the rod burns away, giving off a gas that protects the newly welded area from the effects of extreme heat and oxidization. The flux also helps to keep the arc perform smoothly, reducing sticking.

If the rods were not coated in flux, the newly welded area would be damaged by the effects of oxidization, and would be prone to failure or fast deterioration. Some welders to not use flux-coated rod, but instead feed compressed gas into the weld area during the welding process. These types of welders are called "wire feed welders", but we will be only focusing on the basic arc welder here because it is the most basic type of welder to operate and the most affordable for most beginners.

Although welders fuse metals together using incredible amounts of amperage, it is almost impossible to be electrocuted by an arc welding machine. The reason is that inside a welder is a large transformer, a device that steps down the dangerous voltage in trade for higher "amperage." Amperage, the strength of a current of electricity, can seriously harm or kill, but only if a certain voltage is also present. A car battery can emit more than a hundred amps, which is much more than can be delivered from a standard wall outlet.

But, you can touch both terminals and not feel any electricity. How is this possible? Simply, because there is not sufficient voltage to deliver the amperage to your body. Of course, don't drop a metal object across a charged car battery's terminals or you will have a smoke show you will never forget!

Figure 2

Using an arc welder requires a little practice and patience, but is far easier to learn than any other form of welding. The hardware can be purchased from most retail outlets for a few hundred dollars or less. Anyone can learn to make a clean and strong weld with only a few nights of practice. There are a few different types of arc welders available, and it helps to understand some basic concepts before you buy.

An arc welder is easily identifiable among other welders because it looks like a box with a few knobs on the front, as shown in the photo. There will be no compressed gas cylinders, no spools of wire on top, no foot pedals or any other fancy options needed to make it work.

An arc welder may also be called a "stick welder," "rod welder," or "buzz box", depending on who you ask. When inquiring about an arc welder, you will usually be asked what level of "input voltage" and "amperage range" you want. Input voltage refers to the type of outlet you plan on plugging it into, either a standard 120V wall outlet or a 240V outlet (similar to your household dryer outlet). The amperage range refers to the welder's output power (in amps), and for the type of metal you will be welding. 100 amps would be more than enough.

The 120V (standard wall outlet) type of welders are the most inexpensive types, and will have enough power to weld almost any thickness off steel that would be used in bicycle construction. Another advantage of this type of welder besides the cost is its size. These welders are no bigger than a large microwave oven, and can be moved around by one person easily. The disadvantage of these welders is the output power. Although an arc welder is fine for bicycle frame building, it wouldn't be powerful enough for projects with larger steel components, such a boat trailer frames or motorcycles.

A 240V welder is a commonly used arc welder, and it is quite a bit larger with an amperage rating of at least 200 amps. This type of welder requires a special plug that is easy to install as long, but your building must have 240V wiring. They range in size from 2' to 4' tall or more. These welders cannot be easily moved around unless on wheels, and they weigh 100 lbs or more. The advantage of this type of welder is of course, power.

At 250 amps, you could weld steel plate thick enough to build a ship's hull. The 240V welder is the best unit to buy, as long as you have a place to put it and the proper electrical outlet to plug it into. This type of welder will produce a smoother weld, and will have enough power for any job you may want to do.

Another question you may be asked when purchasing a new arc welder is the output type - AC (alternating current) DC (direct current). AC is the type of current that comes from your wall outlet, whereas DC is the type of current that comes from batteries. Welders that output DC are usually more professional and also more expensive. A dedicated welder will usually prefer DC for most work because it can produce a smoother weld and use a larger assortment of different rods for specialty work.

An AC welder is the most basic type of arc welder, and for the hobbyist, all that is usually required. I have used both types of welders (AC and DC), but choose a basic AC 240V type for my shop, and this has been just fine for building just about anything. Although a DC welder can produce a slightly nicer final weld, a moderately skilled welder will be able to produce a much better weld on a simple AC machine than an unskilled welder could produce on an AC, DC or wire feed welder.

Figure 3

If you are new to all of this welding terminology, make your purchase at a welding supply house. The equipment is only marginally more expensive, but the quality of a brand name welder, combined with the advice of a knowledgeable salesperson is worth the extra cost.

A welder is a tool that will last for a long time, so choose the one that is suitable for your purposes. Besides a welder, you will need to purchase a few other small items before you can make the sparks fly. You will need some protective gear consisting of a welding helmet, welding gloves and safety glasses, as shown in the photo.

Although some welders sold in larger retail stores may include a welding helmet, it's a good idea to get some advice on the type of lens you will need for your work. Lenses come in different shades and are denoted by a number.

The higher the number, the darker the shade. All welding lenses protect your eyes from the damaging rays emitted from the welding arc such as ultra-violet. As your power level setting determines the intensity of the arc, darker shades will be needed as intensity increases. What does this mean to you?

Well, nothing if you don't know much about setting the power level on your welder yet! To weld the light tubing that makes up most bicycle frames, amperage settings between 50 and 80 are commonly used, depending on your skill, and brand of welder. Therefore, a lens shade of 10 would be fine. Shade darkness is not set in stone, and a beginner may want to choose a shade 9 rather than a 10 just because it will be easier to see the work. Of course a shade 9 would be way too light if you had your amperage set at 500, and would feel like you were staring at the sun!

Welding gloves are heavy, heat retardant gloves that cover a large area of your forearm, and this helps keep those hot sparks off your sleeves and out of the gloves. Although bicycle frame welding requires only requires a low power setting, there will still be sufficient heat produced to easily burn a standard pair of work gloves.

The hot sparks flying from the welding rod can find their way into areas such as your sleeves, open collars, and pockets, so at least having gloves that cover your work shirt sleeves can help reduce those painful experiences. A good pair of clear safety glasses or face shield will also be necessary.

After a weld is completed, there is a thin layer of hardened flux from the rod coating the top of the weld area. This flux is removed with a "chipping" hammer, and this process sends hot flakes of flux in all directions, so you must protect your eyes. Some welding helmets allow the dark shade lens to be lifted up, and have a clear glass shield behind the dark lens. This type of helmet will do the job of safety glasses during the chipping of a weld.

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