When I first learned to bend EMT I was taught the "guess and bend" method for offsets, and didn't believe in using tables and formulas.

The person who taught me would bend an offset, check it, bend it again, check it, and usually by the third time it would fit.

Suffice it to say it drove me nuts to do it this way, especially on old work fire alarm jobs that needed lots of offsets and multiple bends. It was extremely frustrating.

Recently, I've learned the Benfield method in school and find it to be far more precise. I can now bend a perfect box offset every time, which is very satisfying!

How do you do it? Any tips for making nice bends?

Peter

Box offsets I always eyeballed.

Other offsets I measured and bent with 30 degree if I could, 45 if I had to. Once in a while I would eyeball an offset.

After fooling around with "eyeball bends" I came to the conclusion my eyeball wasn't very good. I'm a beliver of doing the math & laying out the marks correctly, much faster and, if you are doing multiple runs, then all bends look alike.

I prefer the no brainer 30 degree offset for bends up to about 6". Checkpoint makes a level that has a 30 degree bubble & the level has magnets that are strong enough so the level doesn't fall off the conduit.

Tom

I use a Greenlee offset bender for 1/2" EMT offsets into 1900 boxes and such. Takes less than two seconds and they are all exactly alike. They used to have one for 3/4" but I haven't seen it lately.

For other depth offsets and saddles I use the Benfield method also, although I'll admit that if I'm in a hurry and only have one to do I'll eyeball it.

-Hal

I do box offsets by eye, but for larger offsets, I was taught a different way. However deep your offset is, multiply that by two and thats how far apart your two marks go, then make both your bends using the 30 degree mark. It works perfect every time. For example if you want a 6 inch offset, put your two marks 12 inches apart then use the 30 degree mark to bend them.

I was taught a different way. However deep your offset is, multiply that by two and thats how far apart your two marks go, then make both your bends using the 30 degree mark.

That's the Benfield method, if he could lay claim to something that's commonly done.

-Hal

I use the guesser on box offsets, and math on all the rest (BTW, the 30° on a Benfield is when the handle is straight up & down).

Greenlee "Little Kickers" are pretty cool, but bend a little too deep for most of the boxes we use. Also, they stick sometimes, and you have to rap them on the floor to get the EMT out.

By far the easiest box offset is a Minerallac...S

This is dear to my heart. An important consideration when running conduit is the realization that at some point in the future you will have to pull wires into it. Therefore steps should be taken to ease this impending task. For instance, consider using 22.5º degree bends instead of 30º. Or even better use 10º bends if you can get away with it. The formula for 22.5º is multiply by 2.6. For 10º use 6" for every 1" of desired offset.
Another thing to try is what is known as the super bend -- that is using a larger radius than the standard one shot. This is for 90º. To make it you use your bender like a hicky -- you advance it in small steps and bend the tube at small angles at each step.
45º bends are a killer.
Try to plan your runs to minimize the degree count. For instance instead of 90ºing up out of a box, instead use a 12" offset. This will save 30 to 45 degrees.
If done properly, it should be possible for one man to push the wires in [solid] instead of two to push and pull and chatter.
~Peter

I eyeball box offsets. Biger than that it's the bandfield method. Most of time 30 deg. If you have a newer ideal bender 30 deg the handel is strait up. I don't look at the 30 deg mark on the head just that the handle is strait up. I stamped the multipliers on top of the bender head for when my brain can't think in the morning. Anyone use those little kickers?

Here's a website that has some pretty good information on pipe bending. When you get the main page, go to conduit bending page.
www.porcupinepress.com/index.html

Peter,

I was taught the exact same thing with using the 22.5* and the "super bend". This journeyman made the point that he actually put wire in the pipes he bent once in a while.

I end up doing the math and marking out the box offsets too. While I could probably eyeball it, the reference marks make an adjustment easier if I don't get it right the first time.

Lttle kicker is ALWAYS MISSING!

Next method......

I have a filed knotch site line* for just shy of 22 1/2, (As I dont have 22 1/2 on my bender. Edge of conduit at the front of the hook of the hook on the bender, second bend is marked at the "A" (or is it "B", I don't pay attention anymore) for the front of the hook.

How did I come up with this.....

Trail and error on the site mark until right. And it dog legs less when the hook catches the slight bend at the back of the first bend. (After the bender wears in, a little oil helps)

Its a repeatable angle if you don't change you posture while making the bend.

Unfortunatly, mounting surfaces are not always flat.

Larger off-sets, I always use 30's (obsticale X 2) with my tape on the floor standing up for the distance to check. (Its a repeatable angle if you don't change you posture while making the bend.)

90's I thumb site the back, skip the take-off, (imagining the round back of the conduit) bend to the top of distance as it radius's past my tape. (Lots of practice, usually very acurate, and I don't do it where accuacy counts like racks on a trapeez)Check square on factory cut rock, or plywood, tile lines, etc.

Multiple bends all get marked the same, and get bent the same, at the same time. Layed out on the floor between the marks I shot with the lazer. The get all hung at once. Less up and downs on the ladder or scaffold.

I also have a few methods for 90's and off-sets that dont require a tape measure that are hard to explain in words.

There's the push conduit into corner, mark, flip conduit around and bend on the star method for small sizes where you're going into an inside corner. The EMT stays up a lot better than a tape measure.


BTW-- It's been a while since we've brought this up, but if you want your computer to put in a ° sign, just hold down the "alt" button on your keyboard, and type 0176. Now, let up on alt button. Should be a °.

Try alt with 0216 and you'll get a Ø.
Easier than writing degrees or phase.

Thanks, sparkync, that's a really good site.

Dave

Not so much EMT, but with PVC here, I can look at what's needed for a certain bend or off-set, even multiples, and bend it right there and then.
It's something I suppose that you pick up with experience.
I haven't had a bend that hasn't fitted yet.
Just as a small question, do you guys put a spring-like thing inside the EMT before you bend it to prevent from kinking it?.
We do with PVC, without a spring, it's the quickest way to make a PVC Boomerang!.

HOOAA! Trumpy interesting stuff. So you mechanically bend PVC with out heat? The only way I know of bending PVC here in the states is with heat and I have made many a jig to keep it all straight during the time it takes to cool down.

Never had heard of a spring in the pipe but I have kinked my share of bends in larger 1 1/4" plus EMT.

I have always used the Benfield method except for box offsets. Have had a wallet sized Benfield calculator in my wallet for years. Don't bend much pipe these days.

Trumpy, an EMT bender, or the correct size EMT bending shoes shouldn't deform the EMT so no inside support is needed.

When we bend PVC (RNC) here we use heat to soften it. This can be from a heat blanket that wraps around the pipe or a hot box (oven). Since the conduit whn properly heated is as soft as a rubber hose the larger sizes- 1-1/4" and above require support. I have always used compressed air. We have end plugs for each size, one of each has a connection for an air line. We connect this to a tank of compressed air fitted with an adjustable pressure regulator. Around 6psi will keep the conduit nice and round.

-Hal

Try using a 3/4" EMT - 1/2" RMC bender for 1/2" EMT...

[This message has been edited by DougW (edited 10-27-2004).]

Doug,
I tried that. Crinkled two pipes and gave up that approach.
I think the problem is that the sides of the bender have to closely fit the sides of the tubing so it doesn't ovalize and collapse.
I could see making a larger radius series of benders though.
~Peter

I've always done offsets by eye, but now I know why I need a torpedo level with a 22.5 degree vial. Always glad to get a new tool.

Dave

Check out the "No Dog" offset level.
When making a 90° with an offset at the end, is it best to make the offset first or the 90 first?

One problem with the "No Dog" level, WHERE DID IT GO?! (Otherwise great tool.)

I have lost 3! And now refuse to buy another until everyone else has one too.

Ok, so by now we should be well versed with multipliers for 30's and 45's..

Ever tried in bend a 2 inch offset in 4" emt?
it won't fit, the shoe will hit the first bend.. Not enought distance between bends. need it decrease offset angle, for instance a 15 degree is 3.864.

here's a trick, if you have a calculater, you can figure any multiplier for any degree ofset:
<desired offset angle> * sin * 1/x
so another words, if i wanted the multiplier for 5 degree angle, i would hit 5, sine button, then 1/x button. gives you the multiplier.

Conduit Shrinkage
30 degrees shrinks 1/4" per every inch of offset
45 degrees shrinks 3/8" per every inch of offset
60 degrees shrinks a half inch.

ever seen a 3 pt saddle where the saddle is not centered over the obstacle? thats a huge pet peeve of mine. anyways, a 3 pt saddle shrinks 3/16" for every inch in the saddle.

hope this helps.

Sure you can bend PVC with a bender!
The little stuff, anyway.

Just try it sometime. 1/2 PVC in 3/4 EMT bender, 3/4 in a 1", or 1" in an 1-1/4.

Yeah, it springs back a lot so it's nowhere near as scientific as it could be, but with some practice, it works pretty well.

BigB,
It might be easier to bend the offset before the 90º, especially if you're near the end of the tube. However, it might be easier to pull if you bend the ninety, and then put a kick into it. If you chose a suitably long distance from the 90º, you can achieve a fairly short degree of kick.

On another subject, Tony of Skelly showed me a random technique. He would bend the first bend to whatever he felt like. Then he would measure the desired offset from the floor to the pipe and mark it. I forget the details but he would place the bender in some relation to the mark and make the second bend. I would appreciate any clarification on this if any one has heard of it.
~Peter

I generally eyeball the box offsets, and use the "Benfield" method for the rest.

I've used the "bender handle" method. Bend the first half of the offset, then lay a straight piece of pipe (a bender handle without the belled end of the newer factory handles works fine) parallel against the conduit you're bending, on the opposite side of the bend. Measure your wanted offset depth at a right angle from the inside edge of the straight piece to the conduit past the first kick. Your tape measure will be the "c" leg in the right triangle of the straight piece, the conduit and the tape. Where your wanted measurement meets the kicked conduit, that's your mark. The right angle part is important, too.

Clear as mud?