Electric Arc Welding

An electric arc welder is essentially a low voltage, high amperage power source. It has a cable connection to the handpiece and another cable connection to the project itself. The handpiece holds an electrode which, when tapped against the work, produces a high temperature arc at the electrode tip. This heat is sufficient to melt the tip of the electrode which falls into the weld joint forming a bead as it cools. A flux is necessary and the heat causes the flux to form a gas shield around the weld area. As the electrode is consumed the operator alters the position of the handpiece both to follow the joint and to keep a constant arc gap. Adjustments on the welder itself allow the operator to use a variety of welding rods depending on the nature and composition of the weld required.

Electric arc welders are often portable devices allowing welding to be carried out in the field as required. This is useful on farm applications, mining, pipelines and other outdoor situations. Manual electric arc welding, or stick welding as it is often known, is the most common joining method involving heat that is employed with steel.

Soldering Technique

Solder is pronounced "sodder", the "l" is silent. This page assumes you will be soldering the components to a PC (printed circuit) board. The directions below will get you acquainted with some construction techniques.

Soldering irons, wire, PC board holders and other supplies are in 310. The soldering irons are on timers so that they can't accidentally be left on, but you should try to remember to turn them off when you are done.

Installing a component

To install a component on the PC board, first hold the board with the component side facing you. This is the side of the board with writing on it. Start with the smallest components, usually the resistors. Bend the leads of the device (if necessary) so that they will fit through the hold in the board with the device laying flat against the board. Now bend the leads on the solder side of the board so the device doesn't fall out (see below). You can place several components at the same time.



After several components have been "stuffed" (the technical term for putting components on a board), you can solder them. Before soldering anything make sure the sponge on the soldering stand is moist. You should frequently wipe the tip of the iron on the sponge to keep it clean.

To solder a component turn the board over so the solder side is up. There are some clamps for holding boards in the lab. To solder a connection hold the tip of the soldering iron on one side of the lead and hold it for a second or two. When the lead and the trace are hot, apply solder to the side of the lead that is away from the iron. The solder shouldn't touch the iron directly. This ensures that the connection is hot enough to form a bond with the lead and with the copper trace.



The solder should flow around the connection, and leave a smooth transition from the trace to the lead, as shown. If you have a ball, or the solder has a clumpy appearance you may need to redo the connection. If you need to remove solder we have "solder-suckers" and "solder-wick".

Good Solder Joint	Bad Solder Joint

Gas Welding Welders

Gas Welding Equipment Safety Tips

Acetylene cylinders should be secured in an upright position prior to and during use. Acetylene is packaged in a cylinder filled with Diatemaceous Earth. The acetylene is dissolved in acetone and the solution is then pumped into the cylinder. If the cylinder is placed on its side and then set upright again, it takes some time for the system to reequilibrate and for the acetone to drain out of the dip tube in the valve. If welding is done during this period, the weld will be high in carbon due to the acetone. If welding is done with the cylinder on its side, you may get "spitting".

All cylinders that are not connected for use must be capped. Stored oxygen cylinders must be separated from stored fuel gas cylinders or combustibles by at least 20 feet or by a 5-foot high, fire-resistant barrier with a 30-minute rating.

All cylinders that are connected for use must be lashed or chained; cylinders must be clearly marked to identify the contents. Mark empty tanks with the letters MT, and close the valves and replace the caps securely. Empty cylinders should never be placed where they could become part of an electrical circuit.

Because regulators are delicate, they must be handled carefully. Never use pliers or pipe wrench to attach them. Never pound valves equipped with wheels to open or close them. "Creeping" regulators must be repaired immediately.

Hoses should be color coded to avoid using the wrong hose. Any hoses with leaks, worn spots or burns must be replaced or repaired before use.

Oxygen hose connections are threaded right-handed. Acetylene and other fuel gas hose connections are threaded left-handed. This helps prevent accidentally switching oxygen and fuel gas hoses.

Hoses can be tested for leaks by immersing them in tap water or grease-free soapy water. Do not try to repair hoses with tape.Use only fittings that are bronze or brass (less than 65 percent copper). Never use copper because it forms copper acetylide, which can explode. Never use oil, grease or a similar substance on torches or regulators, because in the presence of oxygen they may burn, or if ignited, explode.

Before hookup always make sure the cylinder outlets are pointing away from each other. This prevents improper mixtures in case a leak occurs. When opening the cylinder valve, never face the gauge--stand to one side to prevent injury caused by malfunctioning valves.

Anyone looking directly at the flame should have eye protection with dark lenses, and if near the torch, a hood to protect against slag. Flash burns are the most common injury associated with welding; they are caused by exposure to ultraviolet light and can affect anyone near the welder even if you are not looking at the welding flame. Although this usually occurs with arc welding, anyone within about 20 feet of a welder should have polycarbonate safety glasses wih side shields, which will block ultraviolet light. Dark glasses are not required to prevent uv burns.

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Welding Safety for Welders

Welding Location
Never weld or cut materials near or around flammable materials. Materials that are flammable, or materials that may catch fire, must be moved a safe distance from any operation that may ignite these materials.

Safety Glasses
Welding helmets do not satisfy the requirement for primary eye protection. Safety glasses must be worn under arc welding helmets to fulfill the eye protection requirement.

Contact Lenses
Never wear contact lenses while welding. Contact lenses can literally be welded to your eyes by the intense thermal radiation produced by many welding processes.

Hot materials
Never pick up hot materials with welding gloves. Never touch metal to see if it is hot. Place you bare hand above the material and feel for radiated heat to determine the temperature. Use a piece of soapstone to label "hot" material if you must leave the area before the material cools down.

Acetylene Regulators
Always set acetylene regulators to less than 15 psi. Above 15 psi, acetylene becomes explosively unstable. Always back the acetylene regulator pressure completely off before installing a new gas bottle. The acetylene valve on the bottle should only be opened 1/4 to 1/2 turn so that it can quickly be closed in an emergency.

High Pressure Gas Regulators
Most bottled gases (exceptacetylene) utilize high-pressure regulators. These regulators should be backed off before installing them on a new gas bottle. The bottle valve has a double seat and should be opened all the way to prevent leakage around the valve stem.

Welding Ventilation
Never weld in an enclosed area without proper ventilation. Many welding operations produce noxious and sometimes toxic gases. Never weld or cut galvanized materials without specially designed ventilation.

Protective Clothing
All forms of electric arc welding and cutting produce extremely intense ultraviolet and infrared light that can cause serious burns to unprotected skin. These intense burns are suspected as promoting skin cancer in later years. Always wear appropriate protective clothing including
welding gloves, long sleeves, long pants, leather footwear, etc.

Wire Wheels
A face shield is required to be worn over your safety glasses when using a wire wheel.

Welding Hoods
Inspect the welding hood before use to ensure that the lenses and filters are in good condition, and of the proper shading, for the operation being performed. Never attempt to weld without proper eye protection.