Even though I'm a carpenter who loves working with wood, I've found that my welding equipment is as useful as many of my woodworking tools. With the right welder and a few basic metal-working tools, I can quickly make repairs to broken equipment or fabricate useful accessories. I don't make critical structural welds on building projects, though; for that I call on a certified welder.
I was first introduced to welding back in my high school metal shop, but it really isn't difficult to learn the basic skills. Our local community college offers noncredit welding classes at night, and there's probably a similar course for adults available in your area, either through a university cooperative extension service or a continuing education program at the local high school or vocational center. With YouTube and all the other online resources that are now available, you could probably teach yourself to weld. My MIG welder came with a useful video that shows how to set up the equipment and demonstrates basic welding techniques, and I've found many helpful basic welding books at the library.
Which Welder?
There are several different welding methods. In high school, we learned to arc weld with a stick welder. With arc welding, current from an AC or DC power supply is used to create an electric arc between the base metal and a consumable electrode - the "stick." Made of a material that is compatible with the base metal, the electrode rod melts into a small puddle that is deposited in the weld area, fusing the joint together.
This process - also called shielded metal arc welding (SMAW) or manual metal arc welding (MMAW) - can create a lot of smoke that interferes with visibility and may make it difficult to get a clean weld. To protect the weld area from atmospheric contamination, electrode rods usually have a flux coating that creates a shielding gas and a layer of slag during the welding process.
I still have the 230-amp stick welder I purchased from a Montgomery Ward catalog some 30-plus years ago, which I use primarily when working with 3/8-inch or thicker metal. It works fine but isn't very fast, because I have to constantly replace the electrode. Plus the slag has to be chipped away before the welded area can be painted.
Wire welders. A few years ago I bought a Millermatic 175 220-volt continuous wire-feed MIG welder, paying about $1,000 for the outfit (920/734-9821, millerwelds.com). If I could own just one welder, this would be the one, because with it I can weld metals ranging in thickness from 22 gauge to 1/4 inch (the most common material thicknesses I work with) in a single pass.
Instead of an electrode rod, my MIG welder has a gun that feeds solid steel wire through an electrically charged contact tip. When I pull the trigger, the hot tip melts the wire, creating a weld puddle. The amp setting and wire feed rate are adjustable, and vary according to the thickness of the material being welded. A handy chart printed on the inside of the welder's access door shows these settings for different thicknesses of metal.
My welder is also equipped with a pressurized tank filled with an inert gas (typically 75 percent argon and 25 percent carbon dioxide - MIG stands for "metal inert gas"). When I pull the trigger to start the wire feed, gas flows out of the gun into the weld area to shield the weld puddle from atmospheric contamination. It costs about $200 to equip the welder with the optional tank, and about $30 to refill the tank.
The 175 has a duty cycle - the amount of time during a 10-minute period that a welder can operate at a given amperage without overheating - of 130A at 30 percent. This means I can weld for three minutes at 130 amps. By comparison, the less-expensive 115-volt Millermatic 135 has a duty cycle of 90A at 20 percent, but it requires only a conventional 110-volt outlet. In the seven years I've owned my Millermatic 175, the safety shut-off has engaged due to overheating only once (though this is partly because I seldom weld nonstop for long periods of time).
A MIG welder works great in a shop environment, but for outdoor work where wind is present, flux wire welding might be a better choice. In flux-cored arc welding (FCAW), the weld pool is shielded by gas created by the flux contained in the wire, so it's less likely to be blown away by the wind. Dedicated flux wire welders are also a little more portable than other welders, because they don't require an external tank of shielding gas. However, the machine does need to be placed within a reasonably close distance - about 10 feet, depending on the length of the feed hose - of the weld site. Some wire welders - including the Millermatic 175 - can handle both MIG and flux-core welding.
