ECN Forum Forums General Topics of the Trade General Discussion Area Pipe bending 101

I am looking for either a web page or a place to get some general knowledge for bending emt basic items 1/2 , 3/4 offsets etc. I have recently needed to begin doing such and need to learn to do it properly. Thanks in advance.

I use these multipliers
10* = 4.0
22* = 2.6
30* = 2.0
45* = 1.4

So if you want 2" of offset, using a 10* bend, mark your pipe at two places 8" apart. Bend on the first mark, turn the pipe 180*, then bend on the second mark.

30* is probably the most common bend. When you are bending on the floor, 30* is when the handle is vertical

When you don't get it exactly right, you can tweak/fine-tune the bend as necessary. The more bending you do, the better you get at it. Happy bending!

Check out this site, it is in depth.

http://www.porcupinepress.com/_bending/TheoryAndDrawings.htm

If you are doing EMT bending you can forget about the 'segment' bending info.

This site has some nice pictures: www.elliottelectric.com/1051/reference/guides/EMTcoduitbending.asp

Here's a book or two you can "take with you": http://www.epinions.com/Benfield_Conduit_Bending_Manual_by_Jack_Benfield
http://www.buildersbooksource.com/cgi-bin/booksite/2304.html

This a link to GreenLee's site : http://edev.colorassociates.com/greenlee/catalognew5000.html : click on the "BENDING" in the turquiose(?) box on the RIGHT

[This message has been edited by Celtic (edited 06-18-2005).]

I have no problem with most of the basic bends. Never did concentric bends and parallel bends take alot of time with paper and pencil for me.

But the ones I have the worst luck with are the stupid little offsets to get into a surface mounted box. Too small to measure and I just don't have the touch.

You get the hang of the box offset when you spend a day making a few hundred of them to feed the pipe running crew.

Parallel, concentric, segment, etc...takes some trial and error. Each machine is slightly different, may be out of alignment, etc. Again, after some "hands on", it does get easier.

The box offset layout is 2 1/4" and the degree of bend is 10. However with pratice you can bend them by feel.First bend a 10 degree kick or something close to it . Then roll the pipe over now gently slide the pipe forward until it feels like ti is going to drop out of the bender. Now bend the second kick. The correct dimention is 3/8". It is a touche fealy way but with a little practice you can master the box offset. I did neglect to mention that I bend offsets with the bender shoe in the air. Thats the way I learned I have seen people bend offsets on the floor but for me thats a hassel. good luck HYPRESS.

I will admit to taking a few lazy ways out.

First of all, it is rare for me to have more than a few bends in a single piece of pipe. I'd just as soon put one bend or offset in a pair of short pieces, as try to get them just right on the first try.

Second, when I have to do a saddle, I will usually make the right saddle in a piece of pipe, then cut the pipe to place the saddle in the right place.

Third, box offsets can be a little large- just roll the pipe a little to the side. Or, better yet- get the $$$ Greenlee tool; then you can add the offset after you've bent the 90, or whatever. You can even add the offset on the wall.

Finally, you must have both an accurate right angle for reference, and a straight edge. Most of the time these are provided by either my truck, or a block wall.

I do almost all my pipe runs 'by eye,' rahter than using all the math. I don't think I've ever used the 'shrinkage' table! This works when you've got pipe runs off by themselves- if you've got a cluster of pipes, and it neds to look really good, then there's no getting away from a lot of layout and calculation. And re-work.

Working with a lot of complicated bends, the best tool to have is a cheap calculator.

When doing multple conduits, do all of them at the same time and do the math. Measure all bends with a magnetic protractor to ensure that they are uniform. Funny how a 31+ degree bend will mess things up, when you needed a 30!

Use a lazer and/or a tight jet line to get those straight runs straight.

To get good box offsets, experiment with a marker on your bender and add site lines where needed, once you have the right marks, file a knotch so they are perminent. You can do the same for site lines front and back of the conduit to reduce do-legs. Then snap a chalk line on the conduit, match that with front knotch for the first bend, then the back knotch for the second. Or eliminate box offsets all together with mineralacs. Although some don't like the look of them.

Beware: If you become an inspector, you will forget how to bend a back to back 90.

I am sad to say that my garage has more couplings than it should!