Annular cutters work best in drill presses or mag drills, especially for holes large than 1" in diameter in metal thicker than ½".” ...

There are LOTS of building codes dictating just how large a hole ... by metal plates; for big pipes, use a long protective ...

With the fate of repetitive motion injury looming due to the need to drill 1,200 holes, [bitluni] took matters into his own hands and built this nifty DIY hole punch for light-gauge sheet metal.