As recently as 40 years ago, the process of fabricating ductwork was incredibly time-consuming. Skilled tradesman known as “tin knockers” individually laid out each galvanized component using templates made of plywood, metal, or cardboard. They’d take a template and sketch out the location of parts on the raw steel before wielding hand and electric tin snips to cut the parts out.
This made the arrival of CNC controlled air plasma systems in the late ‘70s and early ‘80s a welcome addition. Though the capital costs were prohibitive for a smaller company, the larger and more progressive companies understood they’d quickly see a return on their roughly $30,000 investment.