Things You'll Need
Dry erase marker
Angle grinder (optional)
Cast iron bathtubs are solid pieces of metal that have deep sides and often decorative claw feet on the bottom. If you need to modify the plumbing holes or height of the cast iron tub, cutting it is required. In addition, cutting a cast iron bathtub into small pieces is the best method to remove it completely. The challenge to cutting cast iron is to pick the proper saw and blade, as well as use sheer force.
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Open a large drop cloth over the floor area to protect it. Turn the cast iron tub onto its side or on its back. You will need three to four other people to assist with this due to the weight of the tub.
Mark the areas of the cast iron tub that you wish to cut down, using a dry erase marker. If you are cutting the cast iron tub to remove it completely, marking it is not required.
Install a diamond-tipped blade into a standard circular saw, and plug in the saw's electrical cord.
Don a face mask, safety glasses and work gloves before proceeding with the cutting process. Not only will the saw blade heat up the iron, but cutting produces small metal slivers and sharp edges that can cause injury.
Start the saw blade, and cut along the marked lines. If you are cutting the tub to remove it, cut score lines a third of the way in from both ends of the tub.
Turn the saw off, and set it aside. If you are removing the tub, pick up a sledge hammer, and hit the cast iron tub with it, aiming the hammer head at the score lines. Continue hitting until the cast iron breaks into sections. Pick up each section of the tub, and throw it into a garbage dumpster for disposal.
You can also cut through a cast iron tub using a hand-held angle grinder with a diamond-tipped blade in it.