Most shipping container customization plans will involve adding windows, doors, vents, or even opening up a side wall. Cutting Cor-Ten steel, while not as easy as cutting wood, can be done with a number of different tools that you may have available in your typical handyman’s toolbox.
The first and most important thing is to protect yourself while working with cutting tools. Regardless of the tool you select, the cut steel will have very sharp edges; wear a pair of heavy leather gloves such as those designed for welding. The cutting operation involves sparks and metal shavings, wear eye protection! The tools are loud and the steel shipping container will add to the noise, wear good hearing protection! Also wear a heavy long-sleeved shirt and long pants. I know it may not always be pleasant, but it’s better than hot metal shavings falling on you. Speaking of landing on you, shipping containers are constructed of 12 gauge steel, about 1/8″ thick. A large piece of this material, such as a door opening, will be heavy, be careful. when finishing the cut to make sure heavy piece of metal with razor sharp jagged edges will not fall towards you and injure you.
To start, use a Sharpie-style marker to clearly draw the edge of your opening on the steel of the container. If cutting an opening in the shipping container is not or will not become a common practice for you, then you can use a utility saw or reciprocating saw with a heavy steel cutting blade. Save yourself some frustration here, don’t buy cheap blades, they are cheap for a reason, this is heavy duty work and you want to have several strong blades available. Drill a hole inside the line of the marked opening large enough for the saw blade, place the blade in the hole, and begin cutting along the line.
You can also use a skill saw with a good blade to cut flour. To start cutting, first place the blade on your mark to line it up. Raise the rear of the saw enough for the blade to clear the surface of the bowl and turn the saw blade on, slowly lower the saw blade to your mark until the blade cuts through the steel, then follow your line. You will have to repeat this process when you get to the corners, as a chainsaw does not turn. Don’t panic if you go a little out of line with any of these cutting methods, any mistakes can be easily corrected.
Those who cut this type of steel on a more regular basis should have a torch available or the latest field cutting implement, a plasma cutter in their tool arsenal. These will be much faster and easier than saws and much less fooling around corners. You can rent these tools from most equipment rental places, but practice on scrap metal before you start cutting into your bin.
While it is a heavy job, cutting openings in shipping containers is not difficult and can be accomplished with any number of tools, just do it, carefully, and the method that is easiest for you will come to you.