Published: January 2004
Electricians depend on bending tools and equipment to shape conduit and pipe on commercial, industrial and residential projects. Properly used, they make bends accurately and consistently without damaging conduit in the process.
There is a wide selection of hand tools and larger equipment for bending EMT (electrical metallic tubing), IMC (intermediate electrical conduit), rigid pipe and PVC conduit. Which benders will be most effective depends on types and sizes of conduit and volume of work to be done.
Bending equipment includes hand-held, mechanical, electric and hydraulic models. Benders for EMT, IMC and rigid pipe have one component in common—a bending shoe. A groove in the shoe matches the outside diameter of conduit and supports the inside radius and outer walls as the bend is made. For PVC conduit, benders use heat to soften plastic so that it can be reshaped.
Hand-held tools are the simplest benders and have changed little since their introduction. Basically a shoe and handle, hand benders roll the conduit between the tool and the floor, gradually increasing the radius. Shoes for conduit from 1/2 to 1 1/2 inches in diameter are available for most hand benders. Basic hand benders include Benfield-style and Gardner-style models. While both function the same way, Benfield models are made of iron with markings on the heads that are reference points of bend angles. Components of Gardner-style models are made of die-cast aluminum and have built-in spirit levels at the 45-degree and 90-degree positions. Hickey benders are used to make bends when extremely tight radii are required.
Mechanical models are a step up from hand benders. While the force for making bends still is supplied by the operator’s muscle, there are several convenience features. Shoe and bending components are mounted on a two-wheel carriage that can be easily rolled where it is needed and mechanical benders have a platform with a comfortable working height for bending. With some models, the frame can removed from the carriage for mounting on a truck bed or workbench. Interchangeable shoes are used for various conduit types and sizes. Most mechanical benders accommodate 1/2 to 2-inch EMT, IMC, rigid steel and PVC-coated conduit.
High-production bending calls for electric models. These handle the same sizes and types of conduit as hand and mechanical models, but are much faster, making a bend in only a few seconds. Some models can accommodate several sizes of IMC, rigid and rigid aluminum without changing or adding shoes, although different shoes are required for other types of pipe. A simple squeeze adjustment compensates for variations in EMT conduit. Convenience features include programmable capabilities for making accurate repeat bends at the same angles, remote pendant controls and the capability to calculate layout measurements for various bends before work begins. Adjustable operating positions add to user convenience.
Hydraulic benders basically are used strictly for rigid conduit or for conduit in sizes from 2 1/2 to 5 inches, which are too large for electric benders and produce smooth, round bends without conduit squeeze or bulge and without splitting pipe seams. Power is supplied by manual or electric hydraulic pumps.
Compact models accommodate 1 to 2-inch EMT, IMC, rigid aluminum and rigid steel conduit. Larger models can bend pipe to diameters of 5 inches and can be adapted to bend PVC-coated conduit.
PVC conduit is bent after being softened by heat, usually using a hand gauge and guide device to form bends, elbows and offsets.
The most common PVC heating tools are boxes or tubes and blanket heating elements. Conduit is placed inside the box for heating. Blankets can be used to bend pipe already installed and for custom installations by wrapping the heating blanket around conduit where a bend is to be made. Propane heating guns are an alternative to conventional heating methods.
The experts’ thoughts
Representatives of bender manufacturers offer these observations about bending products:
Current Tools Inc. offers electric benders and all the shoe groups for bending EMT, IMC & rigid conduit to 2 inches, bending tables for hydraulic benders and PVC heaters and PVC blankets. Mike Smith, an engineer with Current Tools, said: “Electrical contractors doing residential work primarily use hand benders. For commercial work, hand benders, mechanical benders and some electrical and hydraulic equipment are used. For industrial work, some mechanical tools are used, but most are electric and hydraulic.
“While benders have changed little in the past two years, we have seem EMT usage increase significantly and there has been a steady increase in PVC bender demand for PVC bending equipment. Increased competition in the electric bender market has caused prices to decrease significantly.
“The two most common tools used to bend PVC conduit are heaters and PVC blankets. Heating boxes use either radiant or convection heating elements to soften pipe enough to bend; blankets have a resistance type coil within woven, high-temperature material which is wrapped around conduit, transferring heat to soften the bend area.”
Greenlee Textron offers hand-held, mechanical, electric, hydraulic and PVC heat benders. Chera M. Ellis, Greenlee Textron’s senior product manager, said: “Electric-powered benders are big units for big jobs with large-diameter conduit. They can weigh more than 500 pounds and are typically used by high-volume conduit installers. Electric benders have interchangeable shoes that allow them to handle all types of conduit. Some benders are programmable with digital readouts so the operator can make quick, accurate, repetitive bends. Electric benders use an electrical motor that powers a chain and sprocket drive. Most use conventional AC power, but some have rechargeable batteries that allow use in areas without power.
“Quad benders have an exclusive four-in-one shoe that can handle 1-inch through 2-inch EMT, IMC, rigid steel and aluminum conduit, a patented roller system makes setup for any bend quick and easy, and squeeze adjustment compensates for conduit variations for smooth and wrinkle-free bends. The standard digital pendant control enables programmable bend angles for accurate repeat bends.
“Using hydraulic benders on bender tables locks conduit in place as it bends, keeping the follow-bar, shoe and conduit in alignment,” Ellis said. “A table also makes it easier on workers because they don’t have to kneel to bend conduit.”
Jerry Moser, president of Hotbend Corp., which makes propane- fired heat guns for PVC conduit, said: “The propane heat gun is the only recent change in the way PVC bending is done. Requiring no electricity, the heat gun’s portability, speed and versatility make it ideal for modifying premade bends, making compound bends in a single piece of pipe and for sweeps of unlimited length in PVC to sizes 8 inches in diameter.
“The tool operates similar to a small jet engine, producing hot and high speed exhaust gasses that draw in and mix with ambient air to produce a uniform flow of 1,200 F traveling at 2,400 feet per minute, 6 inches from the nozzle. Its operation is distinctly different than a torch which heats with only a flame and can burn pipe. No warm-up time is required.”
Mary Youngblut is the business unit manager for wire installation products at Ideal Industries, which offers hand benders for metal conduit and PVC heating blankets. She said: “Hand benders are virtually unchanged in design, although some manufacturers have taken steps to make their benders more durable and a bender which doesn’t break during use is a safer bender because the user is less likely to lose balance. The choice is often personal preference or desire to invest in more expensive equipment.
“Hand benders work best for smaller conduit and are available in sizes for 1/2-inch through 1 1/4-inch EMT conduit. Thicker walls of IMC conduit require extra force and it helps to apply consistent pressure during the bending process. Selecting the right tool is important—a 3/4-inch hand bender bends 3/4-inch EMT and 1/2-inch IMC and rigid conduit. A 1-inch EMT bender bends 3/4-inch IMC and rigid.
“Mechanical, electric and hydraulic benders are suited for bending larger conduit sizes, multiple bends and when the job requires a lot of conduit. They all provide additional force or leverage to make the job easier, each version provides a different way to apply this additional force.
“PVC heating blankets have a flat, rubberized blanket that is wrapped around the PVC and heated. Blankets are better suited for smaller diameter conduit and a few bends. Many bends, or bends in larger conduit can be more efficiently achieved by use of a heating box,” Youngblut said.
Klein Tools makes hand benders for bending EMT in sizes to 1 1/4 EMT or 1-inch IMC/rigid; Jeff Konkle is Klein’s product manager. He said: “It depends on the conduit size and the job, but I would say hand benders still are the most widely used bender. While large conduit beyond the capability of hand benders is necessary in many applications, end runs to switches and receptacles are usually hand bent and even the largest of jobs will have a lot of small conduit, end-run bends.
“Hand benders are inexpensive, lightweight and portable. The ratcheting or high leverage of mechanical benders provides more mechanical advantage than hand benders. IMC is larger in diameter and is thus harder to bend. Larger IMC is more likely to require electric or hydraulic power benders. Hydraulic models can be used with manual pumps if electricity is not present.
“Metal conduit remains very popular, while PVC is primarily used in underground or corrosive environment applications. Even where PVC is necessary” Konkle said, “preformed, glued joints are often used, making bending unnecessary.” EC
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at 405.748.5256 or email@example.com.