In a perfect world, every shop would have a plasma cutter, a chop saw, a power hack saw and a metal cutting band saw. No matter what type of metal cutting was needed, there would b a power tool perfect for the job.
But most shops are lucky to have an acetylene torch and a hacksaw, so cutting metal precisely and accurately is a challenge. Fortunately, those two tools can cut a lot of metal, limited in their cutting abilities only by the ingenuity and creativity of their user. Add an air-powered die-grinder and, with a little effort, most metal cuts required on an average farm can be accomplished.
The key to accurate cuts with a torch is patience. It takes patience to take time to clamp a piece of angle iron alongside the desired cutline to create a "guide" when making straight cuts. It takes time to devise a compass-like pivot when making curved cuts. But it takes a lot less grinding to remove slag and straighten or smooth the finished edge if that time is invested before making the cut. A pair of tinted goggles, glasses or a tinted face shield immensely improves accuracy when making cuts. I'm amazed at the number of farmers who still use a torch without eye protection--then apologize for ragged, imprecise cuts.
A plain ol' hacksaw is still the primary metal cutting tool on many farms. Just be sure to match the type of blade, and number of teeth per inch, to the job. In general, a hacksaw blade should have three teeth in contact with the thickness of metal being cut. Otherwise the metal snags between the teeth, especially when cutting thin sheet metal. When cutting very thin metal, it may be necessary to slant the saw blade when cutting to maintain that minimum of three teeth in contact with the metal at all times.
An air-powered die grinder outfitted with an abrasive cut-off disk is a labor-saving alternative to a hacksaw. If all that's needed is to cut off a bolt, slice a pin, or cut an edge off a small piece of tin, an air-powered die grinder will do that job quickly, if somewhat noisily and with a lot of sparks. Safety glasses are a necessity. Ear protection is wise. You can even make long cuts in large pieces of sheet metal by scoring along the marked line, then patiently making repeat passes with the cut-off wheel to make long, straight cuts that require minimal dressing.
And if you're cutting a lot of sheet steel, there are several metal-cutting circular saws on the market that work really well. They look like a conventional wood-cutting electrically powered circular saw, but have high-torque motors built to work well with their special metal cutting blades. They're incredibly noisy and spark-producing monsters, but make cutting sheet metal easy and borderline fun. Don't cheap-out and add a metal-cutting blade to your conventional wood-cutting circular saw--most metal-blades have different size arbors, and if you DO adapt a metal-cutting blade to a wood-cutting saw, you'll soon be replacing that burned out saw because it's not designed for the rigors of cutting metal.