I am in the midst of fixing some farm machinery with new sheetmetal. The metal I am using is 14 gauge, and the proximity to moving parts requires carriage head bolts. The previous metal used 1/4" carriage head bolts, and I would like to do the same. I don't have any idea how to create the square holes. Each piece of metal is roughly 3 feet by 2 feet, and the holes will be within 2 inches of one side of the metal.
Any help would be appreciated.