Choosing the Right Bender
Published: July 2002
All conduit bending requires the aid of a tool. No matter what the diameter of the conduit, you need a conduit bender to bend it accurately into one sweep or another or to create an offset to accommodate an installation. The type of bender best-suited for a job depends upon the size of the conduit and the number of bends that have to be made on site.
Benders that rely on hand and back power alone are suitable for bends of small-diameter conduit when the overall number of bends is low. The leverage afforded by the handle assists the worker in making the bend. Up to a point, the longer the handle, the greater the mechanical advantage and the easier the bending. But even for the smaller-sized conduit, if production is paramount, a hydraulic or electric power-assisted bender might fit the bill and beat the clock. When done correctly, each bend will be accurate and free of kinks.
There are four general categories of benders: hand, mechanical, hydraulic and electric. Each has its niche, though in some cases more than one type could be suitable. With any type of bender, follow the manufacturer’s instructions and, where appropriate, use available adjustments to prevent conduit wrinkles or kinks, particularly on the thinner-walled EMT or IMC. Working with deformed conduit makes wire pulling harder and creates the risk of damaging the insulation on the wire as it moves through the conduit.
Hand benders are popular for ½- through 1½-inch conduit. Generally, they are made of heat-treated iron or aluminum. Some units reinforce the hook and the handle socket, which are areas vulnerable to breakage, with heavier-gauge material. Features that are available in hand benders include permanent hash marks on the tool that facilitate accurate angle measurements, side markings to aid in bending while the tool is inverted and deduct information that is useful for determining the length of the stub.
Other handy features might include a spirit level to help gauge the accuracy of the resultant angle of the bend, offset multipliers that furnish information to create offsets of particular lengths, and a marker that indicates the starting point for back-to-back bending.
Many electrical tool manufacturers offer hand benders, including Gardner Bender, Greenlee Textron, Klein Tools, Ensley and Thomas & Betts. These companies typically make a range of benders to accommodate ½-, ¾- and 1-inch EMT, rigid and IMC conduit. The range of bend sizes possible with hand benders varies among models. Hand benders are available as a unit—bender head and handle—or as separate components, with a given handle that in some models fit more than one bender head. Hand benders can be good solutions for electricians who are doing occasional bends.
Thomas & Betts Ductile-Iron Bender 18-706-TB for 1 and ¼-inch EMT, 1-inch rigid and 1-inch IMC, features embossed benchmark symbols and raised degree-scale markings. The traditional design includes a flat-backed hook on one end of the bender and sports a hinged foot pedal on the other end. The durable tool material is 40 percent stronger than malleable iron, noted the company. The tool, which is guaranteed against breakage for life, includes an offset bending guide on the handle.
Precision cast from rugged malleable iron, the Klein Benfield Conduit Bender No. 51212 features a cast-in degree scale, multiplier scale and large benchmark symbols, including arrow to point to the beginning of the bend and a star that indicates back-of-bend locations. A “teardrop” symbol indicates the center of a 45-degree bend. The bender, which is available with a high-strength steel handle with the distinctive high-visibility yellow finish, has a Zip Guide for offsets, a quick-reference chart for determining bend angles, distance between bends and new conduit length.
Larger hand benders that use a ratchet device to bend conduit are referred to as mechanical benders. Though still only muscle driven, the bender is on a frame that holds the work steady and permits the operator to set a stop bar that ensures all stub-ups or stub-downs are the same length. The frame, or mounting system, may or may not have wheels.
Because the frame keeps the conduit tightly in position during the bend, a mechanical bender facilitates precision bending. And because the handles are typically long, they help protect the operator’s back and arm muscles from injury. A unit may have both a ratchet drive for working with larger-diameter conduit and adjustable stops to help fabricate stub-ups and stub-downs. Typically, a mechanical bender is used on ½- to 2-inch conduit. Mechanical benders may bend one type of conduit (rigid, EMT or IMC) or may have the capability to bend all three types. A universal bending unit uses one, each, of three different shoes and follow bars for each type of conduit.
As with hand benders, a mechanical bender may bend one type or multiple types of conduit. Often, units have cast-in markings, for convenience, stub-ups, saddle bends, back-to-back bends, head-up or down bending and offset multipliers. Some mechanical benders are detachable from the stand, enabling the bender to be bolted onto a workbench or truck for added flexibility. Another available feature is a type of spring-loaded brake system, to prevent spring-back when removing conduit after bending. Mechanical benders are available from a few manufacturers, including Gardner Bender, Greenlee Textron and Ensley.
Hydraulic benders use hydraulic fluid and pressure to assist in bending conduit ½ to 4 inches in diameter. Various models bend conduit within specific ranges. A single unit may bend one type or multiple types of conduit. Because hydraulic benders typically have many parts, they require more set-up time than other kinds of benders. They may be hand pumped (manual hydraulic) or may be driven by an electric pump (electric hydraulic). Some models can provide true one-shot bends up to 90 degrees. An accessory bending table enables the operator to elevate the work off the floor to a height comfortable for working with the conduit and locks the conduit in place as it bends. Hydraulic benders are available from a few manufacturers, including Gardner Bender, Greenlee Textron and Ensley.
A power bender uses a heavy-duty electric motor, a frame and a large shoe to bend conduit without the aid of hydraulic fluid. They bend conduit relatively fast and are often used when there is a high volume of conduit. Using a power bender, a 90-degree bend typically takes 10 to 20 seconds. One product bends all size conduit from ½ to 2 inches, eliminating the need to tote around hydraulic benders with many parts for those sizes. Generally, power benders feature automatic settings that allow for consistent and repeatable bends. They also offer the option of bending conduit with the bender in either a horizontal or vertical position. The capability to switch between the two is an attractive feature because it allows the operator to select bending position dependent upon user preference or space considerations (such as a low ceiling or limited floor space).
Because the electrician is not relying on personal strength to make bends, a power bender reduces the chance of physical strain on the operator when bending larger size conduits, or even some types of smaller conduit, repeatedly. For example, bending ½-inch rigid or IMC by hand takes about 70 pounds of force. As the diameter increases, the force needed also increases. Electric benders are often on wheels, so they are easy to move around.
Gardner Bender’s Cyclone Bender B2000 is a portable, heavy-duty bender riding on two stationary wheels and two swivel castors, that bends ½- to 2-inch steel (schedule 40 max), aluminum rigid, IMC and EMT conduit, and ½- to 1-inch and ¼-inch PVC-coated conduit. The unit, which has an illuminated on/off switch, bends in vertical or horizontal position. A dial-in indicator on the top of the bending shoe facilitates settings. Once the locking handle is released, the operator selects conduit type, size and the angle of the bend, and locks the handle back in place before loading the conduit. A hook attachment on the pendant control frees hands while loading or unloading conduit and keeps the switch out from underfoot. The unit uses one shoe for all sizes, eliminating loose parts. A re-settable circuit breaker eliminates downtime changing fuses. “High/Low” voltage indicators and automatic shutoff prevent damage to the motor from voltage fluctuations. Automatic limit stops facilitate consistent and repeatable bends.
The Greenlee Textron Quad 854 Bender with a pivoting head and four-in-one shoe, bends ½- to 2-inch EMT, IMC, rigid and rigid aluminum conduit without any shoe changes from either operating position—tabletop and upright. The unit, which has adjustable leveler pads to compensate for uneven floors or nonlevel ground and convenient lifting eyes for easy portability, sports a remote pendant switch for safety and bending data charts for easy, accurate bends. The bender has a squeeze adjustment to compensate for variations in the diameter of EMT conduit. By varying the amount of support on the underside of the conduit as it bends along the shoe, the adjustment feature minimizes risk of wrinkling or flattening the conduit during the bend, minimizing scrap. Optional shoes are available to bend PVC-coated steel conduit.
Ensley Tools’ E-688 High-Speed Bender bends rigid, IMC, EMT and 40-MIL PVC-coated conduit, ranging in size from ½ through 2 inches. A powerful 1½-hp induction motor makes it possible to produce a 90-degree bend in conduit up to 2 inches in diameter in 16 seconds. Featuring two 8-inch wheels for easy mobility, the tool operates horizontally or vertically. An at-a-glance, attached bending chart shows all formulas required for bending offsets or 90-degree stubs for all types of conduit. The adjustable stop bar can be preset for fabricating duplicate bends, thereby eliminating the need to measure and mark each piece of conduit before bending. The adjustment limit switch can also be preset to automatically stop the bender at a desired degree of bend, enabling the operator to make quick, accurate and repetitive bends.
Current Tools’ Model 77, bends ½- through 2-inch EMT, IMC, rigid and 40-MIL PVC-coated conduit. The unit features shoes and roller supports that fit the majority of other manufacturers’ benders. The bender, which is Underwriters Laboratories-listed and carries a two-year warranty, uses contactors, rather than printed circuit boards for reliability, according to the company. The handles on the Model 77 pivot to facilitate making a bend without having to deal with possible interference. The unit, which bends in horizontal or vertical positions, features a transformer that renders low-voltage power to the pendant. EC
THE FELDMANS write for various magazines and Web sites. They can be reached at email@example.com or 914.238.6272.