Bending and cutting rebar (steel concrete reinforcing bars) is often necessary when building structural reinforcement for concrete work. It is an easy to work with material that is commonly used in landscaping, art, and other projects where metal that is fairly easy to bend is required. Common rebar is sold by its diameter in 1/8th inch increments (meaning "#4" rebar is 1/2 inch in diameter). Rebar up to #4 can often be bent and cut by hand. Larger diameter rebar is not typically used outside commercial or industrial concrete work and usually requires specialized equipment such as hydraulic shears and benders.
In this article we will assume the use of 1/2 inch (number 4) rebar which is a common rebar found in residential landscaping and concrete work.
Have the right safety equipment.
Rebar can be sharp and is heavy, and can create sparks when being cut. Always wear eye protection, sleeved shirts, long pants, gloves, and sturdy boots when handling rebar.
Setup a workspace.
Rebar comes in very long rods (typically 8-20 foot and up to 40 foot in length). Due to it's length, tendency to be covered with mill scale or rust, and overall weight rebar is usually best handled in a large open area with few obstructions. Cutting rebar often creates very hot sparks so make sure the area is clear of flammable materials. The rust and sparks from rebar can ruin clothing so wear something sturdy and old.
Measure carefully. Taking into account the overall length, any overlap (where you might tie it to another piece), and especially the curves can be a bit tricky. You may find that the first few times you bend and cut a piece of rebar it is shorter or longer than you had intended. This is often due to a failure to account for the length of the rebar through the curve. It can be tricky but you'll get the hang of it. Rebar is very easy to mark with wax crayon (if you'd like waterproof marking) or chalk (often handy in art projects where you'd like the marks to wipe off).
Cut your rebar. Cutting rebar can be done easily with a metal cutting hacksaw blade. You can also use a reciprocating saw, portable bandsaw, or grinder equipped with a blade suitable for cutting "mild steel". Rebar tends to want to roll around when being cut, therefore it is often necessary to step on the bar or have an otherwise steady hold while cutting it. Cut rebar is always hot and/or sharp. Use gloves and caution.
Bending rebar 1⁄2 inch (1.3 cm) or smaller. Now that you have a piece cut to length it is time to bend it. Bending rebar is all about leverage. Place the rebar on the ground. Using a long metal pipe with a large enough internal diameter, place the rebar into the pipe stopping about six inches from the point you'd like to start the bend. Place your foot 6 to 12 inches (15.2 to 30.5 cm) back from where you'd like to bend. Pressing firmly down with your foot, raise the bar off the ground until the bar bends to the angle you'd like. It is often necessary to bend a piece a little at a time if you are trying to get an exact bend
Other methods and tools. You can rent simple manual rebar benders at most hardware stores. If you have a lot of cuts to make renting a metal chop saw is often the most efficient way to cut a lot of rebar.
Source : Wikihow