Welding is a fabrication process that joins metals by melting the workpieces and a filler into a weld pool of molten material that cools to form a very strong joint. The three main types suitable for DIY projects are arc, MIG and inverter welders.
Choose an affordable and easy-to-use welding rig from one of the three categories available for DIY and develop a useful new skill that will enable you to make repairs to metal assemblies and build steel projects without having to outsource.
The basics of arc welding
Joining metals requires the intense heat produced by an electric arc established between the metal being joined and an electrode.
A welding rod is used as the electrode for stick welding, and wire for metal inert gas (MIG) welding.
Electricity for the arc is provided by a power supply and the electrode conducts the current, melting into a weld pool to create a welded joint.
To prevent hot metal reacting with air and forming compounds that weaken the joint, welding rods have a covering that provides a shielding gas at the point of contact as well as slag to cover the fresh weld.
For MIG welding, an externally supplied gas shields the weld. In gasless units, the job is done with flux-cored welding wire instead.
Tungsten inert gas (TIG) welding uses a shielding gas, with a tungsten electrode to strike the arc and a filler material fed separately
by hand into the weld pool.
Not all metals are suitable for welding DIY. One good indication of workability is whether a magnet will attach to the metal, but cast iron is an exception, as it attracts magnets but is very problematic to weld.
Discover the origins of slag and learn why flux is important with our handy guide to welding lingo.
FLUX-CORED WIRE is used with a gasless MIG welder. A metal sheath surrounds a flux core that provides the gas shield to the weld pool during welding.
SLAG is a crust created during stick welding to protect the weld metal from atmospheric contaminants as it solidifies. It is chipped off using a welder’s hammer after cooling.
TACK-WELDING involves making a quick partial weld to hold parts of a metal assembly in alignment before the stronger finishing welds are completed.
WELDING RODS or electrodes are used with a stick welder for jobs involving mild steel and galvanised steel. There are also rods available for braze welding copper, as well as brass, bronze, and other alloys.
WELDER’S FLASH is an eye condition that is usually temporary but causes extreme discomfort. It’s a type of eye burn resulting from brief but unprotected exposure to the bright light of the welding arc that is very high in UV.
Regardless of whether you choose a traditional stick welder or gasless MIG model, you will need specialised safety gear and other accessories.
Wear fire-resistant clothing with long sleeves, like coveralls, when welding, as well as sturdy boots and always work in a well-ventilated space.
Choose an old-school arc welder that uses metal electrode rods, a beginner-friendly MIG model or the latest in versatile inverter welding technology to make strong, permanent bonds between steel workpieces.
Using an electric arc to melt the workpieces and electrode rod, this type of welder tends to take longer to master because of the practice needed, but it works better on dirty or rusty surfaces.
This requires less voltage than stick welding, meaning it tends to be safer. A motor is used to feed the wire to the weld, simplifying the process. MIG units can use a shielding gas or have a design that uses hollow wire filled with flux.
DC inverter welding
Inverter welders are smaller than their traditional counterparts. The arc is easy to start and they typically feature digital current control. Some multipurpose inverters can be used for both stick and TIG welding.
The welding arc’s brilliant light includes ultraviolet and infrared rays that can cause permanent damage to unprotected eyes.
It also produces smoke and fumes, so work in a ventilated area and avoid leaning over the work so you don’t inhale them.
Always wear a welding helmet with a dark lens and long, leather gloves. Keep flammable material away from the work area and have a fire extinguisher on hand.
How to weld
Whether stick or MIG welding, read the instructions on the unit. Know how to adjust the settings to suit the job, then practice. It takes four to six hours to feel comfortable with the tools. Learn how to hold the gun at the correct angle and how to move it to produce a solid weld.
If it attaches itself, then metal can usually be welded. Another test is to nick the metal using a file. If it’s easy to nick, it will also be easy to weld. TIP Specialised techniques are required for welding hardened steel, so it’s not worth attempting DIY.
Using a wire brush, clean the metal surface to remove any paint, dirt, oil or other contaminants. The cleaner the surface is, the easier the welding process will be.TIP For a faster job, try fitting a wire brush attachment to a power drill to clean up the metal surface.
Secure the work clamp to the metal surface, as close as possible to the weld area without impeding visibility or movement. There should be a loud snapping or crackling sound as you weld if the electricity is being conducted effectively. If there isn’t, stop and recheck clamp contact.
Once the welding job is complete, the joint may be encrusted with slag, which can be chipped off using a welder’s hammer. Clean up the area with a wire brush, then repaint to protect against corrosion.TIP MIG welding with a shielding gas does not leave a slag coating.