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by Curtis Von Fange
One of the most useful skills that an owner of older equipment can have is the knowledge and ability to weld. It seems like the older equipment can do a job, albeit slowly compared to newer stuff, but it tends to break more often. Many of the breakdowns are related to the implements that are being used: the disc, wagon or bushog are among them. Knowing how to fix stress cracks, reinforce weak joints by welding on steel support plates, or cutting and shaping parts and adapters out of raw steel plating is an asset that is worth its weight in gold.
For the farm environment there are two types of welding that we will deal with in this series. Arc welding and oxy-acetylene. The latter will also include some pertinent information on cutting torches and fabrication of parts and tools. But we will first cover some basics dealing with arc welding.
Arc welding is as the name implies, welding with an arc. Simply put, a positively charged electrode and a negatively charged steel plate commonly called a ground complete a circuit at the end of a welding rod. When the rod is held a given distance from the item to be welded the current jumps the gap creating an enormous amount of heat. The heat melts the rod end and when the rod is manipulated in a certain fashion a puddle of liquid metal will result which can be controlled to make a weld. Of course it is a little more involved than the simple description above, but the basic premise is that simple; electrical current jumping an air gap melts the metal.
There are many types of arc welding. A few are carbon-arc, metal-electrode, gas metal-arc, atomic-hydrogen, MIG, TIG, and many others. For our purposes we will focus on two basic types of arc welding; AC and DC. It is difficult to explain the difference in simple, down to earth terms so lets just settle for some of the main differences and advantages of each.
AC, or alternating current, is probably the most common and most economical of welders. A good unit can be purchased at a farm store for quite a reasonable price. It will do many simple welding tasks with excellent results. The distinct advantage that AC arc welding has is that there is virtually no magnetic blow, which causes excessive splatter and uncontrollable arcs. The basic features are a good forceful arc, an easy arc to maintain once it is begun, it is great for heavy steel plating because of deep penetration, and is wonderful for welding aluminum. The negative factors are that the initial arc can be difficult to start and that burn throughs on thinner plates of metal can be a frustrating problem. All in all though, a simple AC welder is a good all around tool for general repairs.
DC, or direct current, provides for a more variety in welding. Direct current, by nature, can be manipulated in ways completely different than the alternating cycles of AC. One example of this is that by changing the polarity of current flow different welding characteristics can be realized. Straight polarity, when the current flows from the rod to the base metal, provides a fairly standard arc for a variety of metals. Reversed polarity, when the current flows from the base metal to the rod, provides for 2/3 of the total heat to be centralized in the welding rod tip. This superheats the electrode metal and shielding gas from the flux causing the molten metal to travel at a high velocity resulting in very deep penetration to the base metal. These variations in the types of DC units can accommodate welding on thick or thin metals. This can give quite a bit of flexibility when trying to avoid burn throughs with thinner base metals or working on deeper weld penetration on thicker plates.
As with any trade there are certain hazards which must be addressed when arc welding.
Protective clothing and specialized eye protection must be used in order to reduce these risks. An arc-welding helmet with protective lens reduces the amount of harmful eye radiation and protects the head from splatter and heat. The hair, hands, arms and other skin surfaces must be covered, preferably with heavy leather to shield out other harmful radiation produced by the intense arc. Don't wear regular coverings like heavy cotton or wool as arc welding is accompanied by flying sparks and molten metal pieces that will ignite such clothing. Also avoid pants with cuffs, tennis shoes, thin gloves, and shoes with thin soles.
Avoid electrical shock by working on a dry floor with thick rubber shoes and by wearing dry leather welding gloves. Also make sure to use insulated electrode holders and have the equipment properly grounded. Keep the area properly ventilated to avoid inhaling the burnt fumes. The fumes generated in the welding process may contain highly toxic metal oxides. Keep in mind that you are welding with molten metal. The arc is hot, the metal is hot, and everything in contact with the metal is hot. Watch for falling metal globules; they burn quickly through tennis shoes and unprotected pants. When done welding use tongs to pick up the metal; it does not cool quickly and even when quenched in water beware of the superheated steam it produces when dipped and the heat it retains when removed.
Above all be aware of others around you. When an arc is struck to start welding the sudden flash can cause severe eye damage to onlookers. Continued observation will quickly cause irreversible blindness. Keep people away from the project. Protect them as well as yourself.