Most people buying their first welder get stuck at the same fork in the road: MIG, TIG or MMA. Each process strikes an arc differently and suits a different type of work, so the right choice depends more on what you'll be building than on which machine looks the most impressive on a shelf.
Budget for a first machine is rarely just the welder itself. A gas cylinder and regulator for MIG or TIG, a decent auto-darkening helmet, gloves and basic workshop ventilation all add to the real cost of getting started, and skimping on the supporting equipment tends to cost more in frustration than it saves in cash. It's worth pricing the whole set-up before settling on a machine at the top of the budget.
Cutting capacity is usually described in terms of clean cut and maximum cut thickness, and the two are worth distinguishing. Clean cut is the thickness a machine handles with a good edge finish and reasonable speed, while maximum cut is the thickest material the machine will get through at all, usually slower and with a rougher edge. Buying with your typical material thickness in mind, rather than the thickest job you might occasionally face,
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If you're not sure which supply a particular machine needs or whether your workshop can support it, it's a sensible question to put to a supplier before ordering, and the team at welding helmets and PPE can talk through the options against your existing set-up.
A reliable, adequately sized compressed air supply is the part most first-time buyers underestimate. Undersized or contaminated air, whether from moisture, oil or an undersized compressor, is one of the most common causes of poor cut quality and shortened consumable life, so it's worth checking a machine's air requirements against what your compressor can actually deliver before you buy, not after.
The practical difference comes down to what a machine can draw and sustain. A single-phase supply has a ceiling on how much continuous power it can deliver before tripping breakers or overloading domestic wiring, which is why the highest-output welding and cutting equipment is frequently three-phase only, or offers noticeably better duty cycle performance when run on three-phase. For workshops without an existing three-phase supply, bringing one in usually means an electrician and, in some cases, an application to the local distribution network operator.