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.
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, generally gives a better day-to-day result.
Switching speed, the time the filter takes to darken once it detects an arc, is worth checking against how you actually work rather than assuming faster is always better for every budget. For most general fabrication and repair work, a mid-range auto-darkening helmet with a sensible shade range covers the vast majority of jobs comfortably.
A gas lens sits in place of the standard collet body and uses a fine mesh to straighten the shielding gas flow into a smoother, more laminar stream around the arc. This generally allows a longer stick-out from the cup without turbulence pulling in surrounding air, which is particularly useful when working in tighter joints or awkward positions where the torch needs to sit further back from the work.
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
TEC Products and the components inside.
Duty cycle is one of the most misunderstood figures on a welder's spec sheet, yet it tells you more about real-world usability than the headline amperage does. It's expressed as a percentage over a ten-minute period at a given output, so a machine rated at 30% duty cycle at its maximum amperage can run for three minutes out of every ten at that setting before it needs to rest and cool.