Things to Know Before Buying a Welding Machine
Getting into welding is a step up for most DIYers, so getting the right MIG welding setup for your needs is important.
Types of Welding
There are several different ways to attach one piece of metal to another one, but all welding involves creating a molten pool of metal that joins different parts together. Most welding equipment uses electrical energy to create enough heat to melt the wire onto the workpiece.
The cheapest welding equipment is usually for arc welding, sometimes known as “stick” welding- you hold the welding torch in one hand and a welding stick in the other and touch them together on a metal surface to make a pool of metal.
Metal Inert Gas, or MIG, is probably the most popular form of welding- instead of using both hands, you simply hold the torch, pull the trigger, and a wire is fed from the machine and out of the tip. On contact with the metal surface, the circuit is completed, and the wire becomes molten metal.
Gas and No-Gas MIG Welding
There are two main types of MIG welding- gas and no-gas. Both are types of wire welding- the welding machine feeds a roll of metal wire from a spool out through the end of the torch, where an arc of electricity heats it up on contact with a metal surface.
Gas MIG welding uses bottles of inert gas like CO2 or Argon connected to the welding machine to create a gas shield around the hot arc where standard welding wire meets the metal workpiece. This stops the weld from oxidising before it joins the metal parts together but can be affected by windy conditions.
In no-gas welding, the wire used is hollow and filled with flux which is used to generate a slag to cover the molten metal when you’re welding. This protects it from outside gases in the environment which weakens the bond you are making. The downside is that there’s more splatter when welding, meaning there’s more to clean up afterwards.
Tungsten Inert Gas, or TIG welding is another way to attach two pieces of metal together. Like MIG welding, you use bottles of inert gas to shroud the hot pool of weld from oxidising. Unlike MIG welding, you need to use both hands when working with a TIG welder.
The main difference is that TIG welding doesn’t use a spool of wire fed through a torch head. Instead, you use long rods that are like the ones for MMA or arc welding. It’s a process favoured by some welders for “face” welding when you need to be neat. The downsides to TIG welding is that it’s a lot slower than MIG, and takes more skill to get accurate results.
Types of Wire
The two main types of welding wire are regular steel wire used in gas welding, and hollow wire filled with flux for no-gas welding. When you pull the trigger on a MIG welder, the wire that is fed out becomes an electrode, completing an electrical circuit that creates a high enough heat to melt it where you want a pool of metal.
Welding wire is available in different thicknesses, depending on the size of weld you want to create. Most light fabrication tasks that the DIYer welder will get involved with don’t need wire much thicker than 0.6 – 0.8 mm. Thicker wire up to 1.2 mm is useful for heavy welding applications, but it requires more power than is available in a domestic setting.
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Welding Machine FAQs
How can I make better welds?
Welding is an incredibly useful skill to have. The only way to get better is through practise- try using different heat settings if your welding equipment allows it, experiment with different gauges of wire and don’t be afraid of making an ugly mess on bits of scrap metal in the name of improvement.
The quality of the welding wire you use can make a big difference in the quality of your welds- decent wire isn’t always much more expensive than the rubbish stuff, so shop around and see what the professionals use.
What’s better, MIG, TIG or Arc welding?
All three of these welding methods are great for onsite work. They’re all portable and can join a range of metals together. The downside to MIG and TIG is you need to lug around bottles of gas, where Arc welding uses electricity only. Arc, stick, or MMA welding is not as refined though. MIG and TIG welds are strong and can work on a huge range or materials. If you need to work on very thin materials or need to create intricate, good looking welds, TIG has the others beat. There’s no one system that is outright “the best”, just the better system depending on the job at hand.
Is welding dangerous?
If you invest in the proper safety equipment, maintain your welding gear, and treat it with respect, welding is as safe as any other DIY task. Welding creates sparks that can set light to flammable materials, so make sure you have a fire extinguisher to hand and always keep your work area clean.
Got any welding tips?
If you want to create the perfect MIG welds, you need to take control of your torch. Once you’ve matched the wire feed speed to the correct voltage, the best technique is to move slowly in a tight coil, like you’re drawing a spring, or practicing your lower case joined up “e’s”. This creates an even puddle of weld and a superior join. It’s worth practising this one, a lot.
If you’re welding together a frame, you need to consider the heat that you’re transferring to the workpiece. Weld for too long and you’ll end up warping the entire workpiece due to the heating and cooling process. The answer is to take frequent breaks, don’t over weld and use as few passes as possible.
Whether you’re arc welding or MIG welding, you need a solid connection for the electricity to flow around the circuit and make a stable heat. Always grind back a rusty, painted, or greasy surface before clamping on your earth cable and getting to work. Always weld onto bare metal.
How can I improve the look of my welds?
There’s a saying that goes “A grinder and paint make me the welder that I ain’t” – and it’s true. You can always grind back ugly welds with an angle or die grinder, or paint over the whole thing to hide a multitude of sins.
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