Conduit, both metal and plastic, is used to channel wiring, other tubing, or solid or liquid materials. Installing conduit involves going around corners, under floors, through walls and across ceilings. When installing conduit, you may need to bend the channel as opposed to adding a fitting to make a turn or get through a twisted space. There are several ways to bend conduit, and each has advantages.
When bending conduit, whether it's round, oval or rectangular, it's important to avoid crimping the material at the bend. Crimping is the result of the geometric reality that the inside of the bend is shorter than the outside. This means that around a bend, the outside edge of the conduit will want to take the shortest route, which is a straight line. This causes the conduit to crimp or buckle on the outside edge. Crimping can weaken the conduit and also reduces the interior diameter, making it hard to insert material through the conduit.
The best way to avoid crimping is to bend the conduit slowly and in repeated steps. Don't just grab two ends and pull it around a post. Work the conduit around a form using a level to bend the conduit incrementally. This will allow the conduit to slowly stretch the outside edge and form a curve instead of a collapsed tube.
Plastic conduits are often used to channel electrical and communication wiring. A good way to quickly bend plastic conduit without crimping is to heat the conduit. A 1500-watt air blower set on high will do this quickly. Heat the conduit (but of course don't melt it) and then quickly place it around a round post. Bend quickly and release. For sharper bends, treat the conduit like metal and heat and bend repeatedly in incremental steps.
Another way to bend metal conduit quickly is to make a quick jig. Using a wooden board and large 1/2-inch carriage bolts, make a pattern in the board with the bolts. Insert the conduit and bend incrementally until the conduit wraps around the bolt. Using this trick and you can accurately bend "S" and other shapes by repeatedly bending the length of conduit in different directions and angles.
For larger conduits (1 to 2 inches), use a lever attached to a long handle to work the conduit into a curve. These tools are available at all hardware and tool supply dealers. Hand conduit benders work incrementally but can make quick work of thick, heavy or large conduit.