Support braces and metal structures often require the strength of cast iron. Pieces of cast iron are used as reinforcement pieces of frames and on seams, so in order to mount the cast iron, you will need to drill holes in it to be able to bolt it into place. With the proper tools, you can easily drill through cast iron.
Purchase or rent a post drill press from your local hardware store. This is an upright drill that stands on a post base and has a stationary drill bit that lowers with a spring-loaded wheel on the side of the machine.
Put on your protective eyewear and gloves.
Mark where you want the holes to be on your cast iron with chalk.
Position the piece of cast iron on the post drill stand, or in its vice if it has one. Lower the drill bit by rotating the wheel on the side of the machine clockwise. Make sure the bit touches the centre of the marked hole you want to drill, or position it so it does. Release the side wheel.
Turn the post drill press switch on. Slowly lower the drill bit toward the piece of cast iron by rotating the wheel on the side of the machine clockwise. After you start drilling the piece of cast iron, add a drip of oil in the hole you are drilling so the drill bit doesn't get too hot or stick in the cast iron. Slowly add more and more pressure to the drill bit wheel until you have drilled through the piece of cast iron.
Wear protective eyewear and gloves to prevent iron shavings from getting on your hands or in your eyes.