## Conduit Bending: Concentric Bends

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hey everybody this is Walter with Access

electric and today I wanted to talk

about how to make a concentric Bend

we're going to talk about how we get our

developed lengths and how we make our

marks so we can get our concentric bends

made and we're going to do that on this

bender right here today so let's get

right into it

[Music]

so the first thing I want to do is we're

gonna make a 20 inch radius concentric

Bend with our first conduit so what I

want to do first is find out what my

developed length is going to be to make

a 20 inch radius conduit or to make a 20

inch radius concentric Bend we're going

to need more than 20 inches of conduit

to do that and the way we find that out

is by multiplying our radius by half of

Pi so if you think about half a circle

half a circle or 180 degree circle is pi

so we're we're doing a 90 degree Bend so

we're going to use half pi which is one

point five seven so we're going to take

our calculator and we're going to take

our twenty inch radius times one point

five seven so 20 inches times one point

five seven that gives us a developed

length of thirty-one point four inches

thirty-one point four inches and we're

going to take the thirty-one point four

inches and we're gonna divide that by 17

now we're gonna make 18 marks but we're

gonna have 17 gaps so take 31.4 divided

by 17 gives us one point eight four

inches between our marks one point eight

four inches so we're gonna take about

one and seven eighths of an inch between

our mark so I'm going to start my first

mark about six inches from the end of my

conduit so we made our first mark at six

inches from the end of our pipe and now

we're going to make our 17 marks that

are 1 and 7/8 inches apart so we'll make

our first one and we're just going to go

down our pipe making each mark an inch

and 7/8 from the last mark and we're

going to make that 18 times

and 18 double-checked our marks here 1 2

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

so we have our 18 marks inch and 7/8

apart and now we're going to take this

over to the bender and we're gonna begin

to make our concentric Bend with our

first conduit so we're going to make 18

5 degree bends 1 degree Bend our 1 1

bent for every one of our marks so let's

[Music]

you

[Music]

all right so now we have our second

conduit and we're gonna mark it just

like I did the first one we're gonna

make our first mark six inches off the

end and then we need to figure out our

developed length so we'll turn on our

calculator we're going to take 23 inches

times half of pi 1.57 equals 36 point

one one we're going to take that we're

going to divide that by 17 because we

have 17 gaps and 18 marks so 36 1 1

divided by 17 will give us 2 point 1 2 4

or about 2 and 1/8 inch mark 2 and 1/8

inches between our marks so we're gonna

do 18 marks at 2 and 1/8 apiece so

here's 1 & 2

[Music]

should be 18 marks 1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 18 marks now

we're going to take this over to our

bender I want to start making bends

[Music]

so here we have our two bands here on

the table we have our 1 inch which is at

20 degrees radius and we have our inch

and a quarter which we've been at 23

degree radius and we have them side by

side here and so that's our two

concentric bends so that's how you do it

you take the radius of the bend times

half of pi and that'll give you your

developed length and then you you mark

your developed length either every you

mark mark it nine times four ten degree

bends or 18 times four five degree bends

it kind of depends on how far apart your

marks are the farther apart they are the

more the more the more marks are gonna

have you're gonna want in your Bend that

way you're not ending up with with a lot

of jagged bends on your pipe if you put

them pretty close together like we did

we did 18 5 degree bends the pipe is

nice and smooth all the way through the

bend so that's how you do it concentric

bends with an electric bender thanks for

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