Is deduct only for ninties?

[zappy]

Yes that is what I'm saying. I'm tring to find the gain for kicks

Yes that is what I'm saying. I'm tring to find the gain for kicks

For every bend, you gain a little bit of distance. We typically measure straight-line run distance. Every bend shortcuts that distance with a curve.

For example, put a 90? bend on a 10' stick and of course it is no longer 10' long in one direction... but add the distance covered in both directions and it will be greater than 10'. The amount greater than the straight length is your [90?] gain.

So say we have a 3/4" stick of rigid. A 90 degree the gain is 4". So if I dived 4" by 90 that should give me the gain per degree. Correct?

 

[zappy]

You are smart

You are smart

On paper, conduit per degree of bend is constant. Varies a little in actual bending.

Gain can be determined by formula, but it is not linear... i.e. the gain of a 45? bend is not 1/2 that of a 90? bend. Let's see... the 45? arc length is (pi)r/4 while a 90? arc is (pi)r/2, but the straight-line distance of a 45 is 2r?tan22.5?, or approximately 0.828r, while that of a 90 is 2r. So the gain, on paper, is 45? @ 0.828r ? (pi)r/4 and 90? @ 2r - (pi)r/2. If you trust my math, they reduce to 45 @ 0.0426r and 90 @ 0.4292r.

So "pi" means pie? the "r" stands for? This symbol / means dived? Whats the "I" stand for? Can you put that in laymen's terms?:jawdrop:

 

[zappy]

Yes. A straight piece of pipe, with one bend in it.

Yes. A straight piece of pipe, with one bend in it.

I think Zappy is asking how to accurately measure and mark a 45 degree "stub" (half of a 90 degree stub).

He used the word "kick" which many interpret as meaning "offset".

I have needed to do this a few times before, but know of no sure way to get it right the first time. And many of those times it is not necessarily 45 degrees but just random angle that we need to match. With EMT you usually end up making it long and cutting it. With rigid or IMC that may make it difficult to thread if you have to cut after bending so I see his problem.

Yes indeed. I would like to cut and thread first, then bend and it fits the first time. I have been just bending them long, hold the piece up, then mark it, then cut it, then thread it with a hand threader. But after 2" there is no hand threader.

 

[K8MHZ]

Yes indeed. I would like to cut and thread first, then bend and it fits the first time. I have been just bending them long, hold the piece up, then mark it, then cut it, then thread it with a hand threader. But after 2" there is no hand threader.

I was trained that when running threaded pipe you cut and thread first.

Each bender is different, so every time you work with a different one you should do some test bends and actually measure stub height, gain and take up. There is a little green book I use (not Ugly's, thats for code stuff) that is great for pipe bending. It's out in the van, or I would give you the name. I use it on just about every threaded pipe job and it's also great for EMT if you want to be exact.

A great tool is a nice bending table where you can lay your finished pipe on a nice flat surface and measure everything before you attempt to install it. This is where 'fine tuning' takes place and makes for a much easier installation.

 

[Dennis Alwon]

So "pi" means pie? the "r" stands for? This symbol / means dived? Whats the "I" stand for? Can you put that in laymen's terms?:jawdrop:

surely you jest but if not pi is a constant= 3.14, r= radius and this symbol "/ " means divide--

 

[K8MHZ]

surely you jest but if not pi is a constant= 3.14, r= radius and this symbol "/ " means divide--

In second grade pi was

3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609

Now it's just 3.14?

Not much of a constant if you ask me......:dunce:

 

[Smart $]

So "pi" means pie? the "r" stands for? This symbol / means dived? Whats the "I" stand for? Can you put that in laymen's terms?:jawdrop:

"(pi)" is the constant related to circular geometry having a value of 3.1415926535897932384626433832795... and usually rounded to a many less significant digits

"r" is the radius value (usually center-line radius)

I didn't use an "I"...???

For the task at hand, using math will get you close. Using a scrap piece to mark, bend, then use to make supplemental measurements will [typically] get you closest on the second try. Yes, scrap costs the same as installed, but consider the cost of time it takes to do the math, only to get you close. Sometimes that close isn't good enough, taking even more time to get it right. So in the end, which costs less???

 

[jumper]

"(pi)" is the constant related to circular geometry having a value of 3.1415926535897932384626433832795... and usually rounded to a many less significant digits

"r" is the radius value (usually center-line radius)

I didn't use an "I"...???

For the task at hand, using math will get you close. Using a scrap piece to mark, bend, then use to make supplemental measurements will [typically] get you closest on the second try. Yes, scrap costs the same as installed, but consider the cost of time it takes to do the math, only to get you close. Sometimes that close isn't good enough, taking even more time to get it right. So in the end, which costs less???

Nice job on this advice and the math earlier, I thought I was gonna be wrong on the math and I was. I appreciate your time in posting the trig. I admit I mostly run small stuff these days and just cut off the excess.

 

[jumper]

On paper, conduit per degree of bend is constant. Varies a little in actual bending.

Gain can be determined by formula, but it is not linear... i.e. the gain of a 45? bend is not 1/2 that of a 90? bend. Let's see... the 45? arc length is (pi)r/4 while a 90? arc is (pi)r/2, but the straight-line distance of a 45 is 2r?tan22.5?, or approximately 0.828r, while that of a 90 is 2r. So the gain, on paper, is 45? @ 0.828r ? (pi)r/4 and 90? @ 2r - (pi)r/2. If you trust my math, they reduce to 45 @ 0.0426r and 90 @ 0.4292r.

Cool thanks.

 

[Stevareno]

Using a scrap piece to mark, bend, then use to make supplemental measurements will [typically] get you closest on the second try. Yes, scrap costs the same as installed, but consider the cost of time it takes to do the math, only to get you close. Sometimes that close isn't good enough, taking even more time to get it right. So in the end, which costs less???

This.

I understand the OP's dilemma, but IME it is much more time effective to use a scrap piece of pipe, put reference marks on it, make the bend, hold piece to where it needs to go and mark where the cuts need to be.
With that information, it is much easier to make an accurate bend without having to do the math.

 

[zappy]

This.

I understand the OP's dilemma, but IME it is much more time effective to use a scrap piece of pipe, put reference marks on it, make the bend, hold piece to where it needs to go and mark where the cuts need to be.
With that information, it is much easier to make an accurate bend without having to do the math.

I've thought about using ceiling wire. make it the bend you need, cut it, mark the center of bend, straighten it out and measure it.

That would give me the length of pipe I need to cut and thread.

 

[zappy]

I was trained that when running threaded pipe you cut and thread first.

Each bender is different, so every time you work with a different one you should do some test bends and actually measure stub height, gain and take up. There is a little green book I use (not Ugly's, thats for code stuff) that is great for pipe bending. It's out in the van, or I would give you the name. I use it on just about every threaded pipe job and it's also great for EMT if you want to be exact.

A great tool is a nice bending table where you can lay your finished pipe on a nice flat surface and measure everything before you attempt to install it. This is where 'fine tuning' takes place and makes for a much easier installation.

I would like to know the name, when you get a chance. Thank you.

 

[Smart $]

I would like to know the name, when you get a chance. Thank you.

He might be referring to Greenlee Conduit Bending Handbook.

 

[K8MHZ]

I would like to know the name, when you get a chance. Thank you.

It's this one by Richard A. Cox

View attachment 5959

http://www.coxco.net/Conduit_pipe_Bending_Book_p/b0010.htm

 

[zappy]

It's this one by Richard A. Cox

View attachment 5959

http://www.coxco.net/Conduit_pipe_Bending_Book_p/b0010.htm

That's a good book. I have that one. I also have a book called simplified conduit bending. This book talks about stuff not in the one you mentioned. Also comes with these plastic cards with stuff I don't really get. I'm sure this book has everything, it's just hard for me to understand.

 

[K8MHZ]

That's a good book. I have that one. I also have a book called simplified conduit bending. This book talks about stuff not in the one you mentioned. Also comes with these plastic cards with stuff I don't really get. I'm sure this book has everything, it's just hard for me to understand.

Is it this one?

http://www.conduitbending.com/Products.htm

How much does it get into Chicago benders? My fave, I own two of them.

I would also like to see a book about 'by eye' bending using hand benders. I have been taught some cool tricks from j-men over the years but never have seen a book about it. For 1/2 and 3/4 EMT, I rarely use a ruler to make up to 3 or so inch offsets. I knew a guy that could make any EMT bend there was just by holding a stick ruler up to the pipe and bender, never making a mark on the pipe and his bends were perfect. He was also so familiar with building materials that he could bend 3 and 4 bend saddles to for ceiling runs without measuring what he was jumping and they would be perfect every time. When we met, he was just getting ready to retire and I was an apprentice. He would stay on the ground and bend pipe and we would go up in the lift and run it. He was amazing.

 

[quogueelectric]

pipe bending 101

pipe bending 101

I not talking about a offset. Just a kick. And I'm wondering how you can cut and thread a piece of pipe first then put a kick in it and make it fit. There must be some gain that needs to be subtracted. So say 1/2 rigid 90degree bend you would gain 3"1/4. So what would you gain on a 30degree bend? A third of 3"1/4???

If you are bending 1/2 in rigid the takeup of a 3/4 emt bender would be 6 inches not 5 so for example if you wanted to bend a 66 inch elbow you would deduct the takeup of the elbow which is 6 in and subtract it from your overall length 66-6=60" place this mark on the arrow at the front of the shoe and bend your 66" elbow up to 90 degrees.

 

[quogueelectric]

Kick

Kick

What if I want to bend a kick at say 30 degrees, to reach a coupling 17" away. Would I just mark the pipe at 17" and put it at the front of the shoe and bend it till it reaches 30 degrees? Thank you for your help.

In order to bend a kick using a 30 degree bend you would have to understand the concept of the 30 60 90 degree triangle which is in a relationship of one two square root of three. if a coupling ran through a deck 17 inches off the wall where a pipe is running the 30 degree relationship is 1 to2 so for a 17" kick as the one and the hypotenuse as the two just measure back to your center of bend mark 34" and bend the pipe to 30 degrees and you will have a 17" kick.

 

[quogueelectric]

Back to back

Back to back

I kept seeing 2 1/2"in some of the other posts which I beleive is half of the radius of 1/2 " emt I saw you post that what you are bending is rigid which would make the takeup 6" for a 90. I believe you have some of the formulas mixed up a little so I will try to explain the difference in you can bend back to back ninety s in the same direction using the standard 6" deduction for each ninety or instead of bending in the same direction you take 1/2 of the takeup and ADD it 3" to the overall distance and bend it in the opposite direction using the arrow on the front of the bender.

 

[readydave8]

I've thought about using ceiling wire. make it the bend you need, cut it, mark the center of bend, straighten it out and measure it.

That would give me the length of pipe I need to cut and thread.

Will that work being that the ceiling wire is not the same diameter as the pipe?