How to Bend Mild Steel Tube

Method 1: Use a tube bender to bend mild steel tube

1. Purchase a tube bender. Your local hardware store has a variety of tube benders at different price points. The main differences may include the amount of hydraulic pressure the tube bender can apply to the tube and the size and durability of the accompanying dies.
The die is the curved part that attaches to the tube bender and the tube is placed into the die to form the bend. Different dies correspond to different diameters of tube. In addition, you can also find die sets for round or square tubes.
Make sure you buy a tube bender and not a pipe bender. Tube and pipe are not synonymous and even have different proportions, so the dies in a pipe bender will not fit the pipe properly. This often results in a flat, bent, or kinked pipe bent with a pipe bender.
2. Follow the instructions. As always, a specific machine may have specific steps due to design or other requirements. Please carefully review the instructions that come with the equipment.
3. Choose the appropriate size die for the tube you need to bend. For example, if you need to bend a 1-inch tube, you should choose a 1-inch die.
It's important to use the right die. If the tubing doesn't fit snugly into the die, then the final product may be flat or twisted.
4. Place the tube into the tube bender. With the die attached, place the tube into the bender so that the point you want to bend is centered in the die. Then tighten the tube bender (which comes with an air jack) to keep the tube in place.
5. Measure the correct angle. You can't set a tube bender to a specific angle and let it do the rest, so this means measuring the exact angle you need the tube to bend.
The simplest solution is to use a digital angle gauge, which you can attach to a horizontal tube before you start bending. As you gradually bend the tube, the angle gauge will track the angle measurement.
6. Bend the tube to the angle you want. As the force of the tube bender increases, the tube will bend to a greater angle. Once your angle gauge measures the angle you want, you can release the pressure on the tube and remove it from the machine.
7. Practice with a scrap tube. Since using too much force can still cause a bent pipe to kink, practice on scrap pipe before putting more expensive pipe into the pipe bender.

Filling the pipe with sand before putting it into the pipe bender can also help the pipe bend evenly without buckling or kinking.

Method 2: Using a blowtorch to bend mild steel tube

1. Purchase a blowtorch. If you don't already have a blowtorch, you may need to use an acetylene blowtorch for this method because it requires continuous high temperature.
2. Place the pipe in a vise. Clamp the vise down hard so that the pipe cannot move; however, do not apply too much pressure to avoid crushing the pipe.
Some vises have slots specifically for clamping round pipes. This is desirable, but not necessary.
3. Heat the pipe where it needs to be bent. When using an acetylene blowtorch, you need to apply constant, even heat to the area that needs to be bent. Make sure to apply heat to the entire cylinder (or square) of the pipe, not just the side that needs to be bent. The extra ductility will help the pipe bend evenly instead of just at one point.
4. Bend the pipe slowly and firmly. Do not jerk the pipe. Instead, bend it slowly and firmly, gradually increasing the force. 
(1) You can use a wrench, a larger pipe wrapped around one end as a crowbar, or your hands to apply force. However, the pipe will be very hot, so wear thick, heat-resistant gloves.
(2) This step may require assistance so that one person can apply force to the pipe while the other continues to heat it.
(3) Filling the pipe with a non-combustible material such as sand before heating it will help the pipe bend without buckling or kinking.

5. Bend to the angle you want. One of the easier ways to measure the bend with this method is to make a template for the bend and then cut it out of another material, such as scrap plywood. As the angle increases, remove the heat long enough to hold the template against the bend and gradually increase the angle accordingly.

Method 3: Bend using a pipe roller

1. Purchase a pipe roller. If you need to form a uniform arc over several heats of pipe, rather than bending it all at once, a pipe roller will produce better results. You can find tube rollers at most hardware stores, and they are actually cheaper than pneumatic bending equipment.
Like tube benders, tube rollers may come with a set of dies so you can fit the exact size tube you need to roll without risking it flat.
2. Place the tube into the roller. Tube rollers work by applying more force to a tube and then rolling it back and forth under the force to create an even bend. Start by placing the tube into the roller, using the appropriately sized dies to hold it in place. [9]
With a tube roller, you will start at one end, not in the middle.
3. Clamp the roller with a clamp until it is tight. Most tube rollers have a hexagonal head, so you can use a regular wrench to increase the force of the clamp.
4. Manually roll the tube over the roller. For basic tube roller models, the device simply has a large wheel that feeds the tube into the roller and applies force to the roller by turning the wheel.
Turning the wheel requires a bit of force, especially as you increase the force on the tube with subsequent passes.
5. Increase the force on the tube. After passing the tube through the roller from one end to the other, you should tighten the rod about a quarter turn more to increase the force on the vise.
6. Roll the tube back the other way. The wheel on the roller can turn left and right, so the more pressure you put on the tube, the more you can roll it back the other way.
7. Repeat until you reach the desired angle. After each pass through the equipment, continue to tighten the roller a quarter turn and roll again. After a few passes, you will notice a nice, even arc forming on the tube. Continue rolling until you reach the desired angle.
If you have a template that allows you to precisely control the desired angle, then you can adjust the angle it is in the tube again after each pass until you achieve the effect you want.