Pipe bending, with a hand bender question
- Thread starter zappy
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hardworkingstiff
Senior Member
- Location
- Wilmington, NC
You could always just bend a piece and measure, then you'd know. I do that with a new bender just to see if it works like is should.
It actually not a linear ratio, but rather a trigonometric one. The ratio for any bend less than 90? would be the sin of one-half the bend degrees. In the case mentioned, it works out to 3". Note you have to use the deduct value from the tangent point (where the conduit actually starts to bend) as some shoe's "deduct" amount includes a short section of unbent conduit (such as with Greenlee 555's).
ohmhead
Senior Member
- Location
- ORLANDO FLA
Well calculation and trig is good but there is nothing like actual bending .
We bend lots of pipe mostly 1 1/4 to 6 inch emt & rigid . BUT 1/2 also its important
Any shoe has a center point and from that center to your end of shoe collar is a length of measure at different angles its the same length on shoe but stub length will change from that end point out .
This is you key to that shoe or size conduit once you know it your done record it in a book for that shoe .
You can bend back to backs in reverse on greenlee 555 or 881 easy with this method by knowing gain or shrink of shoe .
We take our electric benders & hydr benders and record these measurements we bend each size pipe and at every angle from 2 degs to 90 degs and record gain and shrink of which type shoe and conduit of that size.
Once you do this you never need a chart you have angle to length of stub and at any deg its good to do this then you can bend any pipe size on any bender without a book or chart . only measure with a pencil marks need to be thin to be accurate
We bend lots of pipe mostly 1 1/4 to 6 inch emt & rigid . BUT 1/2 also its important
Any shoe has a center point and from that center to your end of shoe collar is a length of measure at different angles its the same length on shoe but stub length will change from that end point out .
This is you key to that shoe or size conduit once you know it your done record it in a book for that shoe .
You can bend back to backs in reverse on greenlee 555 or 881 easy with this method by knowing gain or shrink of shoe .
We take our electric benders & hydr benders and record these measurements we bend each size pipe and at every angle from 2 degs to 90 degs and record gain and shrink of which type shoe and conduit of that size.
Once you do this you never need a chart you have angle to length of stub and at any deg its good to do this then you can bend any pipe size on any bender without a book or chart . only measure with a pencil marks need to be thin to be accurate
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e57
Senior Member
- Location
- San Francisco, CA
It actually not a linear ratio, but rather a trigonometric one. The ratio for any bend less than 90? would be the sin of one-half the bend degrees. In the case mentioned, it works out to 3". Note you have to use the deduct value from the tangent point (where the conduit actually starts to bend) as some shoe's "deduct" amount includes a short section of unbent conduit (such as with Greenlee 555's).
I skip almost all the math in most off-sets and other situations by 'eye-ballin' the center of bends with a straight edge... (A wall line, concrete joint, level, another stick, etc..) Make the first bend - then stick a straight edge near it - mark the approximate center (the longest point between the two straight lines.) and measure to the hook line made before, this is what you need for the next one... This works great when duplicating a bend (by someone else) , or if you over or under bent, or changed the first of an off-set to an unkown angle.
ohmhead
Senior Member
- Location
- ORLANDO FLA
Bender handle straight edge
Bender handle straight edge
Well thats kinda the way 40 years ago we bent pipe before books came out on how to bend conduit by example we would bend the first offset at any angle then lay it down on floor take the hand bender handle and use the handle as a straight edge laying it side by side to the first bend then take a ruler and measure your inches to long side of conduit needed for the rise of your offset and mark the conduit at that point then just pick it up and using the bender standing up right on the floor bend your second bend you could see or roll it in bender to get that dog leg out by eye with out a level and it was good to your eyes.
We use to and still use a wooden ruler its great for offset calculations you just bend the ruler to size in field area of offset needed then bring it down flat on floor and measure with your regular ruler you got your offset leave it bent and check your bent pipe to it check it out .
Its also good for finding your degrees of bend needed in field placement before you start the old wooden ruler it great for stuff like that .
Not perfect but good for inwall stuff but then mc came out and no one bends conduit anymore .
Bender handle straight edge
Well thats kinda the way 40 years ago we bent pipe before books came out on how to bend conduit by example we would bend the first offset at any angle then lay it down on floor take the hand bender handle and use the handle as a straight edge laying it side by side to the first bend then take a ruler and measure your inches to long side of conduit needed for the rise of your offset and mark the conduit at that point then just pick it up and using the bender standing up right on the floor bend your second bend you could see or roll it in bender to get that dog leg out by eye with out a level and it was good to your eyes.
We use to and still use a wooden ruler its great for offset calculations you just bend the ruler to size in field area of offset needed then bring it down flat on floor and measure with your regular ruler you got your offset leave it bent and check your bent pipe to it check it out .
Its also good for finding your degrees of bend needed in field placement before you start the old wooden ruler it great for stuff like that .
Not perfect but good for inwall stuff but then mc came out and no one bends conduit anymore .
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electricalperson
Senior Member
- Location
- massachusetts
theres a couple good conduit bending books on the market too. benfield has one. thats the technique i use and it works fine
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
ohmhead
Senior Member
- Location
- ORLANDO FLA
Well the old wooden stick ruler still has some good uses today when we splice HV cables . We do not use a metal ruler do to metal fragments & dirt thats always inside .
To prevent contamination of the insulation and the semicon while splicen cables most roll up rulers are not clean .
We use a wood ruler and wipe it with mineral oil thats what we use on splicing and terminating HV cables and sometimes we use a wooden yard stick there just easy to keep clean and we have never had a splice blow out yet.
ELECTRICIANS GUIDE TO CONDUIT BENDING BEST BOOK IN THIS TRADE EVER BY RICHARD A COX
To prevent contamination of the insulation and the semicon while splicen cables most roll up rulers are not clean .
We use a wood ruler and wipe it with mineral oil thats what we use on splicing and terminating HV cables and sometimes we use a wooden yard stick there just easy to keep clean and we have never had a splice blow out yet.
ELECTRICIANS GUIDE TO CONDUIT BENDING BEST BOOK IN THIS TRADE EVER BY RICHARD A COX
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cadpoint
Senior Member
- Location
- Durham, NC
All you have to remember is the Star and the kotch in the bender, and which way your bending it to hold or create the point off of those marks.
I'd buy either a Dr. Watson or an Ugly, both have simple and complex bending equations and way more other valuable information inside each book, then just a bending book. But it's your money... OH and JMO
I'd buy either a Dr. Watson or an Ugly, both have simple and complex bending equations and way more other valuable information inside each book, then just a bending book. But it's your money... OH and JMO
I don't know about that, but it can still be purchased...
http://www.amazon.com/Electricians-Guide-Conduit-Bending-2nd/dp/B001N3PPOO
ohmhead
Senior Member
- Location
- ORLANDO FLA
Well most construction books stores have it but its been a while since ive purchased mine hows 1982 when it first came out all the IBEW schools had it as they teach bending in class .
Also for just conduit bending as the OP has asked Greenlee has a book for all there benders basic to advanced bending its a good reference also its free just ask at you local electrical supply house like Graybar .
Most electrical supply houses also give you a free uglys book just ask they usally have them but you got to ask .
Good luck have a merry xmas
Also for just conduit bending as the OP has asked Greenlee has a book for all there benders basic to advanced bending its a good reference also its free just ask at you local electrical supply house like Graybar .
Most electrical supply houses also give you a free uglys book just ask they usally have them but you got to ask .
Good luck have a merry xmas
I know this isn't going to be elegant enough to suit a lot of you folks, but it works, and I'm way past worrying about how what I look like any more...
I lay a tape measure down beside the conduit, hold the bender in the position where I want the finished bend, and then carefully roll the bender down beside the pipe to where I can pick up the conduit just enough to slide it into the bender. It is automatically in the correct position with the right amount of take up.
Another thing I usually do if I can, is use 30 degree bends on an offset, because they are twice as far between the bends as you want the offset.
Now, if you are using a hydraulic bender, or if you need a specific degree bend, you'll hafta figure it out, but if you're just bending some plain ol' conduit runs, why not do it the easy way when you can?
I lay a tape measure down beside the conduit, hold the bender in the position where I want the finished bend, and then carefully roll the bender down beside the pipe to where I can pick up the conduit just enough to slide it into the bender. It is automatically in the correct position with the right amount of take up.
Another thing I usually do if I can, is use 30 degree bends on an offset, because they are twice as far between the bends as you want the offset.
Now, if you are using a hydraulic bender, or if you need a specific degree bend, you'll hafta figure it out, but if you're just bending some plain ol' conduit runs, why not do it the easy way when you can?
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The only thing I really know are the stub, back to back and, for offsets, double the distance @ 30 degrees (handle straight up).
I eyball a LOT when I'm bending small pipe.
If I have a tricky bend, I try to get it with one stick/one shot, but I'm not afraid to use couplings and a hacksaw/sawsall
I eyball a LOT when I'm bending small pipe.
If I have a tricky bend, I try to get it with one stick/one shot, but I'm not afraid to use couplings and a hacksaw/sawsall
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I did these by eye with a folding ruler in about 15 minutes. I've never learned a book or formula method. I only use 1/2" and 3/4" on a regular basis, but I've worked with everything up to 4".
These 3/4" EMT's were for coming out from under an elevated walkway, and into and back out of a column, for a lighting project for the Richmond Convention Center.
There's a couple of shots of the skywalk. If you look atop the second-from-the-bottom horizontal rails, you can see the track lights, which are computer-controlled.
We had to run MC down each vertcial rail and fish them out to the tracks. The arch was designed by an artist named Ed Carpenter, who also programmed the lighting.
The slats are made of what's called dichroic glass, which has some interesting effects on the light passing through them. They look extra cool at night as the lights change.
These 3/4" EMT's were for coming out from under an elevated walkway, and into and back out of a column, for a lighting project for the Richmond Convention Center.
There's a couple of shots of the skywalk. If you look atop the second-from-the-bottom horizontal rails, you can see the track lights, which are computer-controlled.
We had to run MC down each vertcial rail and fish them out to the tracks. The arch was designed by an artist named Ed Carpenter, who also programmed the lighting.
The slats are made of what's called dichroic glass, which has some interesting effects on the light passing through them. They look extra cool at night as the lights change.
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