Bending metal tubes for a custom fabrication project may seem like a relatively straight forward process, but it takes more than a vice and consistent pressure to get a smooth bend. Some materials are especially prone to kinking, creasing, or wrinkling when you try to bend them. This is especially true with thinner or weaker metals, like aluminum or copper, but even steel pipes can have problems. The following tips can help you avoid creases and kinks so your project comes out looking its best.
Tip #1: Use wet sand
Creasing and kinking happens when one side of the pipe collapses before the other side has achieved the desired curve. This is the nature of trying to bend hollow, thin-walled materials. You can minimize this issue by filling the tube with a substance that is still malleable but prevents the side of the tube from collapsing and creasing. Wet sand is just the substance. Simply pack the pipe with the sand before bending it. You can then rinse it out once you have the desired bend.
Tip #2: Heat the pipe
Heat can make a pipe more malleable, which means it will bend more easily without developing a crease. The heat method works especially well on copper tubing, which is why there is a small handheld blow torch made just for use by plumbers. Wearing heat-proof gloves, use the torch to warm the pipe in the area where you are planning to bend it. Then, slowly bend the pipe to the desired angle, stopping to reheat the metal when needed as it cools.
Tip #3: Use a guide
The most common method for DIY pipe bending is to do so with the help of a vice. The vice holds the pipe in place while you slowly bend the free end as needed. You can further ease the bend by using a second vice to support a pipe or other circular object that mimics the angle of the desired bend. Take the free end of the pipe, either with sand in it or heated as desired, and slowly bend it around the guide object. This can prevent the inside wall from collapsing.
Although these methods can help you bend a pipe yourself, you may want to hire a professional pipe bender or fabrication company if you will be bending a lot of pipe or if the pipes must be bent accurately to function correctly. They will have both the knowledge and the proper tools for the job.