Benders
A bender is a tool that contains a partial circle casted in a metallic substance called a shoe. The conduit is placed within the shoe and is pressed down to create a bend. Shaped from the radius of the shoe.
Deduct
The deduct is used when figuring where to mark the conduit to bend a 90˚ bend. It's a value subtracted from the desired stub length and marked on the conduit to create the stub.
This value changes depending on the type and size of the bender being used.
Centerline Radius
The centerline radius is determined by the manufacturer of the bender.
Types of Benders
There are several different types of benders. They're all similar, but operate in different ways. These benders are Hand, Mechanical (Chicago), Electric, and Hydraulic benders.
Regardless of their differences every bender has a deduct/take-up. This point can vary from being an arrow mark, or a point at the front of the hook. Sometimes it can be the center of the shoe. Depending on the bender you're using.
Hand Benders
Hand benders are the most used benders within the electrical trade since they're inexpensive, and easily transportable. Typically sized for smaller EMT conduits such as 1/2", 3/4", 1" and 1 1/4". You can also use hand benders on rigid conduit as long as the conduit is one trade size smaller then EMT, and the bender says it's capable of it.
Hand benders have several marks to help you bend conduit.
note
These marks are generic and not all manufacturers are the same.
Arrow: The arrow mark indicates the beginning of the deduct. Typically you'll use this mark when bending a 90˚ bend.
Star: The star mark is used when bending a 90˚ bend backwards.
Rim Notch: The rim notch(es) will vary depending on the manufacturer of the bender, but typically the rim notch indicates the center of a 45˚ bend. Some benders will use several notches to determine the center of 30˚, 45˚, and 60˚.
Degree Marks: The degree marks are found on the back end of the bender's shoe. Most benders have degree marks for 10˚, 22.5˚, 30˚, 45˚, and 60˚. These marks indicate how far to bend the conduit. The conduit is at the desired bend when the side of the conduit facing the handle is parallel with the corresponding mark.
Deduct for Hand Benders
Fortunately, the deduct for hand benders are pretty consistent regardless of the manufacturer.
| Bender Conduit Size | Deduct |
|---|---|
| 1/2" EMT | 5" |
| 3/4" EMT | 6" |
| 1" EMT | 8" |
| 1 1/4" EMT | 11" |
Mechanical Benders
Mechanical (Chicago) Benders are benders with a ratchet to hold pressure on the conduit while bending. They require the operator to pull back on the handle in order to bend, and to bring the handle back up to release the ratchet. The desired bend may take multiple instances of this action.
Chicago benders don't have markings on the shoes. The deduct benchmark is located at the front of the hook and the deduct amount is usually found on the side label.
These benders vary depending on the manufacturer, but the shoes are sized from 1/2" - 1 1/2". Intended for rigid conduit. Some benders may have all these shoe sizes available, and some only a certain sized shoe for the bender. However, the most used Chicago benders: Greenlee's 1800 and 1801. Are split from (1800) 1/2" - 1" and (1801) 1 1/4" - 1 1/2"
tip
If the shoe loosens up between bends, try placing another pipe through the shoe as a handle to hold it in place.
Electric Benders
Electric Benders are operated by an electric motor that is controlled by a remote that is usually hooked up to the bender. These benders are commonly used when working with a lot of rigid conduit, but they can also be used on different types of conduits depending on the make and model of the bender/shoe.
Like Chicago benders, electric benders don't have markings on the shoes. The deduct benchmark is located at the front of the hook and the deduct amount is usually found on a label on the machine.
Hydraulic Benders
Hydraulic Benders are large benders usually used for 2 1/2" conduit and larger. These benders are normally setup on a table and require a hydraulic pump in order to bend the conduit.
There's two different styled shoes for hydraulic benders. The One-Shot shoes are similar to the shoes used all of the other benders. The other style are the Rigid-Only shoes, which presses into the conduit to bend while supporting the conduit before and after the bend.
One-Shot Shoes
One-Shots are similar to all the other benders in shoe design. The deduct is based on the front of the hook, and are unmarked.
Rigid-Only Shoes
Rigid-Only shoes are half-moon shaped, and instead of pulling the conduit to bend it pushes in. The shoes are intended for rigid conduit. The rigid-only shoes have a mark in the center. The mark is the deduct benchmark.
The shoes are sized from 1/2" - 5". From 1/2" - 4" you can bend a 90˚ in a single shot, but when using 5" you'll have to use segmented bends for bends larger then 15˚.