Shop notes

What a 120-volt household outlet lets a welder do, what 240 volts adds, how dual-voltage machines work, and what to check before you plug in.

What each auto-darkening helmet spec means: shade range against OSHA's minimums, arc sensors, switching speed, viewing area, optical class, power and grind mode.

How the four common arc welding processes differ in shielding, skill, speed, outdoor use and the metals they suit, and how that maps to the machine you buy.

How plasma cutter makers rate cut capacity, what air supply a cutter needs from your compressor, why pilot arc matters, and how to size a cutter to the thickest steel you cut.

What a welder's duty cycle rating means, why it's always tied to an amperage, how to compare machines rated at different points, and how much you actually need.

How many amps it takes to weld a given thickness of steel, which MIG wire size suits that current, how to set wire speed, and where the rule of thumb stops working.

What welding fume contains, why coated and stainless steel need extra care, and OSHA's practical steps: stay out of the plume, ventilate, and use exhaust or respiratory protection.

OSHA's minimum lens shade numbers for MIG, flux-core, stick, TIG and plasma cutting by current, how to choose within them, and what an auto-darkening helmet's range has to cover.

OSHA's fire-prevention rules for welding and cutting, translated for a home garage: the 35-foot rule for combustibles, shields, extinguishers and a fire watch.