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.
An auto-darkening welding helmet uses a liquid crystal filter that switches automatically from a light state to a dark shade the instant it detects an arc, then reverts once the arc is gone. This replaces the older habit of flipping a fixed-shade visor down and up by hand, which meant either welding blind for a split second or lifting the helmet to check your position before striking the arc. 3M Speedglas is one of the ranges we point people towards most often for this, alongside other options across different budgets.
Space and power supply are the other two practical constraints worth checking early. Confirming that a chosen machine will run comfortably from the electrical supply actually available in the workshop, and that there's room to work safely around it with materials laid out, avoids the common mistake of buying a machine that then can't be used the way it was intended.
Ambient temperature and airflow around the machine also affect real-world performance. A welder working in a hot, poorly ventilated space, or one that's been boxed in against a wall with no clearance for its cooling fan, will hit thermal cut-out sooner than the same machine used with proper clearance in a cooler environment. Keeping vents clear and giving the unit room to breathe protects both the duty cycle you paid for and the components inside.
The collet and collet body hold the tungsten in place and need to match its diameter exactly. A worn or incorrectly sized collet allows the tungsten to shift slightly during welding, which affects arc stability in ways that are easy to blame on technique when the actual cause is a consumable that needs replacing. CK Worldwide and Furick are two of the ranges we stock here, and these are inexpensive parts, but neglected ones cause a disproportionate amount of frustration at the torch.
For anyone starting out, talking through process, budget and set-up with people who deal with first-time buyers regularly is generally worth more than another hour of reading spec sheets, and that's exactly the sort of conversation the advice line at www.tecproducts.co.uk is there for.