Conduit bending, tricks of the trade.

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brother

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"I have learned, in whatsoever STATE I am, therewi
I know this is not an NEC question, but just curious as to anyone would like to share some 'tricks of the trade' in conduit bending? :idea:
Im always looking for faster and easier ways of bending. :D
:?:
Ive learned a few on my own, that have been very useful, but would love to hear from others.
8) thanks.
 
I find large pipe runs (especially rigid) to be a breeze when using a "no-dog":

nodog.jpg


This is the original no-dog.
See: www.no-dog.com/

nodog.gif


Greenlee went a bit more hi-tech here:
Z508-1027.jpg
 
Last year, I got that fancy Greenlee, in Celtic's picture above, at a big box called Fry's ~ U$D 30.00, but removed that tether cord, since it sneeked under the magnets and altered the reading too often.

-------Some hard lessons learned while bending conduit--------
A. Don't try to learn isolated from the crew. Weakness is seperated from the hurd & is first to get smoked.
B. If working for hire alone, these are the hard knocks learned by me.
1) Raceways require foot-per-hour performance. Let boss take heat for plan & route, first.
2) Bossman must see unhesitated actions and results. Stress over angles in the toilet.
3) Bone yards of bad bends & waste survived, where slow contemplation got smoked.

C. These are the Red Flags that got me & others smoked.
1) Too many trips up & down the ladder, or missing tool belt or material pouch.
2) Blood & bandages everywhere, cutting hands rather than pipe.
3) Can't get the right bend, or carying the bender up the ladder with you.
4) Standing on top or straddling ladder, rather than getting a taller one.
5) Struggling with fittings after straps are nailed down, or on oval pipe ends.
6) Diagonal short cuts, when runs should be perpendicular to each other.
7) Cutting before bending, or using an "offset" where a "kick" should be.
&) Smashing oversizded holes through walls, or taking time to make perfect holes.
9) Using a protractor (dial guage) for anything smaller than 1-1/2".
10) Blood shot eyes, wearing clothes with another trade logo - look I don't belong here!

If one man shows do much conduit, that may be the most civilized way to learn.
 
celtic said:
I find large pipe runs (especially rigid) to be a breeze when using a "no-dog":
Click to expand...

I recently bought 3 of tools at the No Dog site. :)

The No dog

A level with 15, 30, 45 degree, plus plumb and level vials.

A high quality protractor.

I have a lot of pipe to fit in a small space, I can't wait to try the new stuff out. 8)
 
celtic said:
I find large pipe runs (especially rigid) to be a breeze when using a "no-dog":
Click to expand...

I recently bought 3 of tools at the No Dog site. :)

The No dog

A level with 15, 30, 45 degree, plus plumb and level vials.

A high quality protractor.

I have a lot of pipe to fit in a small space, I can't wait to try the new stuff out. 8)
 
ramsy said:
10) .... wearing clothes with another trade logo - look I don't belong here!

.
Click to expand...

That was something I used to do to have some "fun" with the other trades on large jobs (200+ manpower count).
Plumbing foremen would stop and ask my foreman "Why is MY guy helping YOUR guy pull wire?"
Plumbing foreman - :x
My foreman - :lol:
 
A long time ago - before I went back to school and became an engineer - I worked as an apprentice. I remember there was a specific procedure to bend an offset. I think we made the first bend, and then measured off a line extended from the straight part to figure out where to start the next bend. But it also seems like we added 7" for 3/4" conduit. So to get a 5" offset, you would measure 12" off the first part.

Is that anywhere near correct? In not, can you refresh my memory?

Steve
 
steve66 said:
Is that anywhere near correct? In not, can you refresh my memory?

Steve
Click to expand...

Not even close...LOL.

Let's say we have a piece of pipe(size doesn't even matter) and we need a 10" offset in it:

offsets.htm_txt_Offset.gif

Determine what size angle you want - 30 degrees sound good?
Find the multiplier for 30 degrees - x2
10"x2= 20"
You need to space the marks 20" apart BEFORE bending.

Some people will "try" and make the 1st bend, lay pipe down, get a straight edge (like the bender handle), then "try" and get a measurement that is 10". Good luck finding the center of the first bend and just where do you put the mark for the second bend? Is that the center, bottom or top of the bend...and where do you line up the bender?

The multipliers for the bends are the same regardless of pipe size...the ONLY thing that matters is the desired angle.

The multiplier is actually the cosecant of the angle. Most people have the common cosecants commited to memory, some have a "cheat sheet" at their disposal, etc.
Here is a short list of common angles and their multipliers (cosecants):
15 - x3.86
22.5 - x2.61
30 - x2
45 - x1.41

For a deailed explanation of pipe bending, check that link I posted previously.
 
Ok Celtic, but the way I was taught, we didn't have any idea what angle was used. We just bent it until it looked good, then we would measure and mark the conduit. Finally, we would make the second bend until the conduit looked like it was going straight again.

Also, I can't figure out what good it is to mark the distance from the center of the bends. When you put the conduit in the bender, the shoe is the start of the bend. The center of the bend would be back some distance depending on the radius of the bend and the angle of the bend.

I also remember frequently "taking a little out of a offset" by smacking the conduit on the concrete floor :D

My bends usually had some pretty bad dogs, I would usually have to find a good spot between some columns and braces to pry the conduit aginst.

Steve
 
Ok Celtic, but the way I was taught, we didn't have any idea what angle was used. We just bent it until it looked good, then we would measure and mark the conduit. Finally, we would make the second bend until the conduit looked like it was going straight again.
Click to expand...

No offense...but you weren't taught anything. Someone showed their convoluted way of making pretzels out of pipe.

You don't need to know what size angle to use - unless dealing with multiple runs or trying to match existing runs. What you need to know is how much bend is in the run between pull points.

"Guessing" is not being taught.


Also, I can't figure out what good it is to mark the distance from the center of the bends. When you put the conduit in the bender, the shoe is the start of the bend. The center of the bend would be back some distance depending on the radius of the bend and the angle of the bend.
Click to expand...

Let's look at this from bending a 90.
Say you have piece of 1" EMT, the shoe calls for an 8" take-up.

You measure from the end of your last pipe to the wall/obstacle and get 35.75". Marking and bending the pipe at 35.75" will give you a pipe that is 8" too long. What you do is deduct the take-up from that 35.75" mark, So the actual bend mark is now 27.75".

Now imagine you have a rack of 1" pipe that has a set before that 90. All the other pipe looks picture perfect.
Are YOU going to be the one that makes the whole rack look like something Fido left behind?
Of course not.
You get out your protractor and lay it on the set. ...all of a sudden that set that you thought was 30 shows it as a 22.5..


So now you know the angle (22.5 w/multiplier of 2.61).
You can easily measure the height of the set against parts of the builing or by other means (laying a pipe across the rack to establish one side as "level") Now you see the set is actually 13.375".
2.61 x 15.375 = 34.90875...just shy of 35".

Now you know the height of set (13.375") and the distance between bends (just shy of 35")...but where do you put the first mark???/

If you could find the center of the existing bends (which is quite easy), you could put your mark on the pipe, using a mark on the bender that shows "center"....Greenlee benders have a "star" that indicates center:

23564.jpg


See it there...just below where the handle would be inserted?

A bender that doesn't have a center mark can be easily found using some scrap, a sharpie, and a ruler.

It's these little things that seperate a journeyman from a mechanic (mechanics work on cars).





I also remember frequently "taking a little out of a offset" by smacking the conduit on the concrete floor :D
Click to expand...
Try that with some 4" RGC

My bends usually had some pretty bad dogs, I would usually have to find a good spot between some columns and braces to pry the conduit aginst.
Click to expand...

That will take some practice using the proper methods...you just need to be taught the right way (as opposed to any which way, just make it fit).
The link I provided above has a wealth of information.

When you get to break out some serious brain cells on a rack of pipe all different sizes but all RGC you will see there really is a method to the madness. Then when you are confronted with a rack of 3/4" EMT, you'll laugh at it - especially when you overbend/kink the first bend :) ...

Bending pipe is a form of art. In this day and age of "faster and cheaper" and "slam-jam and scram", the art is on it's way to oblivian.
When one of the guys from Chicago reads this thread, I am sure he will have some "tips" (Chicago is an anti-rope-slinging town)



**********
EDIT: Who busted the "quotes"?
 
1] Survey your entire route ahead of time. Consider potential sources of support and obstacles way down at the other end. Realize that you will eventually have to pull wire into that tubing, so make it easy on yourself.

2] So use 22? offsets instead of 30?. Use the controversial super bend to ease the pull. See ericksenbender.net. In general, minimize the amount of bends. Have the pipe enter the box via an offset rather than a 90? stub.

3] Kicks are pretty good things. To get them exact, make a mark on a nearby wall and kick to that. Or open your tape measure to the desired kick [minus the thickness of the case, of course] and set it vertically on the floor and bend to clear or whatever. If you over bend, a bit of pressure by jumping on it -- well actually more of a CPT maneuvre -- will work. In worse cases, scissors lifts have built in "fork-lift slots" for this purpose.

4] Don't not bother trying to bend 1 1/4" EMT unless you weigh 260 pounds and are over 6' tall.

5] The California Bend-- In tilt-up construct, there is often a big I beam sitting on top of the wall where it meets the ceiling. It projects inside the wall, maybe 4", preventing a simple 90? to go up the wall and then across the ceiling. The old approach was to create a 4" offset and then a 90? resulting in a total of 150?. The California Bend starts with a 45? bend maybe 8" below the obstruction and finishes with another 45? at the ceiling resulting in a total of 90?, a savings of 60?.

6] For 10? bends, 6" will yield a 1" offset. Thus 3" will yield an approximate box offset. For real precision, have your boss get the company a Greenlee offset device.

7] Make sure you have the complete range of fittings and support devices for the size you are using. You might be using Caddy clamps for most of your run but in one spot, the only way to support your pipe is to use a beam clamp, all-thread, conduit hanger [Minie] arrangement. Or, entering a panel, there is a piece of UniStrut so you will need the right size of UniStrut strap for it. 1/2" are 56 cents each. [Hey! The company couldn't, wouldn't afford a box on a million dollar project. So I used a spring nut, a 1/4-20 screw and a Minie to achieve the same result.] [Also a 1/2" one hole strap and a teck screw screwed into the edge of the strut.]

8] Bemders usually leave about 2" of straight pipe at the ends of the bend. If space is short, you may cut this off. However, the pipe at this point is slightly ovalize and the fitting won't fit. This can be ameliorated with a few deft strokes of a multiple dimensional impact director.*

~Peter

*bureaucratese for "hammer"
 
thanks for the info, what i learned from experience is where to place the bender on the conduit for the center of odd ball angles without using scrap pieces of conduit. :D May not seem like much but i remember asking this question about 2 years ago, and most said you just had to use a scrap piece and mark the bender when it sat. then you know the center. Believe it or not there is a 'science math' to it.

for example, I had to find the center of a 18 degree angle (odd ball angles :shock: )when i did some runs and match the existing runs so my run would be parrallel.

not all benders are the same, greenlee is different from ideal (as im sure most of you know). so the placing of the shoe would be different.

most come with the knotch for the center of a 45 degree, so to find other angles (or at least get close enuff for the eye) for every 15 degree from 45 (45 and under) just add 3/8 in front of the 45. that will help you find the center of the bend on the shoe. anything over 45, like 60 degrees or more is a more tricky, it starts at 3/8 but changes. :(

Hope this made sense. it help me in time and guessing and marking the bender for those runs. So no matter what existing runs are there for kicks or offsets, (most offsets are 30, 22.5, 45 anyway) You can match it quickly and easily without using a piece of scrap conduit to find it first or having to just be a little long and cutting it. :)
:idea: :idea:
 
brother said:
not all benders are the same, greenlee is different from ideal (as im sure most of you know). :
Click to expand...

GB benders are not like any I've used...that seem to automatically twist (dog) the pipe :twisted:
 
hey_poolboy said:
I think one of the steel manufacturers owns GB and designs the bender to destroy conduit so that we use more.
Click to expand...

I cut my teeth on Benfield benders in the late 60's. Don't know who owns them now, but they were the best I ever used. Jack Benfield authored several books and pamphlets on conduit bending. I've hardly ever bent a piece of conduit that didn't fit using his methods.
 
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