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Old 08-10-2017, 10:38 PM   #1
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Default I am confused about kick 90's

So today I bent two kick 90's and the math did not work out. While I did get the kicks I needed, I get quite annoyed when 2+2 does not equal 4. So I was bending a 12.5" kick at 22.5 degrees in a 4" pipe with a 36". After I bent the 90 I measured 32.66'' from the back of the 90, and made my first mark. Then I measured 2.35" and made my second mark(this was my deduct, closer to the 90). When I put it in the bender 18 degrees ended up being what got me the 12.5". So any thoughts as to what I did wrong? thanks
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Old 08-10-2017, 10:42 PM   #2
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Not all benders are created equal.
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Old 08-10-2017, 11:08 PM   #3
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Default I am confused about kick 90's

Depending on the bender the mark for your kick needs to centered in the bend radius. So for 22.5 the mark would be at around 11 on the shoe.
I come up with 33 3/8 from the 90. So the arrow mark would have been somewhere around 30" assuming the radius of the shoe is 14".







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Old 08-10-2017, 11:10 PM   #4
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were the steps at least right? Is there any way to get in tune with this bender?
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Old 08-10-2017, 11:13 PM   #5
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were the steps at least right? Is there any way to get in tune with this bender?


What bender?


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Old 08-10-2017, 11:13 PM   #6
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A few things.

When you measure from the back of the 90, you have to add half the width of the pipe, not deduct.

That is the center to center distance of the bends. So this mark now needs to be placed on the center of the 22.5 degree mark (at 11.25 degrees from the start of the bend), not the benchmark or hook of the shoe. you need to bend a scrap piece at 22.5 to find where this mark is on the shoe, or do a lot of math.

With this size conduit you also start to run into the fact that the conduit does not follow a straight line segment path. It has a radius and a gain factor. Luckily with this small of an angle of bend, it will probably only throw you off a quarter of an inch.

Most bending apps don't use the cosecant method. They use the center line radius method which is more accurate, especially with larger conduit/radiuses and steep bending angles like a 45.

The RigidPRO app will tell you where to place your mark to the bench mark or to the center of the bend. you can toggle between the two even after the bend has ben calculated.
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Old 08-10-2017, 11:19 PM   #7
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So it sounds like measuring from the back of the 90 is my first issue. Also just to confirm the size of my pipe does not matter right?
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Old 08-10-2017, 11:41 PM   #8
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Originally Posted by platypuselectrician View Post
So it sounds like measuring from the back of the 90 is my first issue. Also just to confirm the size of my pipe does not matter right?
Are you trying to get me to say size doesn't matter?

The size doesn't matter, but with the larger size comes a larger radius. that can throw you off, especially if you are using the cosecant method. You need to do the cosecant method and then subtract the gain amount for the degree and radius to be accurate. I am probably making more out of it than you need to worry about.

The gain on large conduit comes into play on 45 degrees and up.

With a piece of 3/4" EMT try and bend a 20" offset using two 90 degree bends. Since the cosecant of 90 degrees is 1 the multiplier is 1. So a 20" offset using 90's would have the two bend marks 20" apart. When you are done, and measure your bend, it will be off by quite a few inches because of the gain.

Last edited by cabletie; 08-10-2017 at 11:45 PM.
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Old 08-10-2017, 11:44 PM   #9
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Ok so wow you just said a lot,
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Originally Posted by cabletie View Post
A few things.

When you measure from the back of the 90, you have to add half the width of the pipe, not deduct.

(So I add half of the pipe width to my first mark pushing me further from the 90 right?)

That is the center to center distance of the bends. So this mark now needs to be placed on the center of the 22.5 degree mark (at 11.25 degrees from the start of the bend), not the benchmark or hook of the shoe. you need to bend a scrap piece at 22.5 to find where this mark is on the shoe, or do a lot of math.

(I think I will have to go with the math as I have been asked for bends from 10-45 degrees. Is there someone at greenlee that might already have this information for the 881?)

With this size conduit you also start to run into the fact that the conduit does not follow a straight line segment path. It has a radius and a gain factor. Luckily with this small of an angle of bend, it will probably only throw you off a quarter of an inch.

Most bending apps don't use the cosecant method. They use the center line radius method which is more accurate, especially with larger conduit/radiuses and steep bending angles like a 45.

The RigidPRO app will tell you where to place your mark to the bench mark or to the center of the bend. you can toggle between the two even after the bend has ben calculated.(I will download the app)
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Old 08-11-2017, 12:40 AM   #10
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Originally Posted by platypuselectrician View Post
So today I bent two kick 90's and the math did not work out. While I did get the kicks I needed, I get quite annoyed when 2+2 does not equal 4. So I was bending a 12.5" kick at 22.5 degrees in a 4" pipe with a 36". After I bent the 90 I measured 32.66'' from the back of the 90, and made my first mark. Then I measured 2.35" and made my second mark(this was my deduct, closer to the 90). When I put it in the bender 18 degrees ended up being what got me the 12.5". So any thoughts as to what I did wrong? thanks
I've had bosses that would fire you for measuring such kicks... too slow.

For production speed you scarcely measure.

Start by bending the 90 -- leaving plenty of stick to work with for your kick.

Then, using a common tape measure at the same time, bend the kick to the distance needed.

Finally, trim off the pitiful amount of excess EMT that would through you off.

Such a short amount of EMT is not worth the labor burn to save it.

And with cordless bandsaws, you can lop it off in seconds.

Your EMT won't even show any Sharpie marks.

The beauty of this technique is that you can re-tweek it if your first kick attempt is off a tad. You only trim for final fit after you're satisfied.

Sometimes you'll have to trim from both ends -- but so what ?
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Old 08-11-2017, 01:53 AM   #11
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QUOTE - [ What bender?].

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Old 08-11-2017, 06:37 AM   #12
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Greenlee 881
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Old 08-11-2017, 06:45 AM   #13
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Quote:
Originally Posted by telsa View Post
I've had bosses that would fire you for measuring such kicks... too slow.

For production speed you scarcely measure.

Start by bending the 90 -- leaving plenty of stick to work with for your kick.

Then, using a common tape measure at the same time, bend the kick to the distance needed.

Finally, trim off the pitiful amount of excess EMT that would through you off.

Such a short amount of EMT is not worth the labor burn to save it.

And with cordless bandsaws, you can lop it off in seconds.

Your EMT won't even show any Sharpie marks.

The beauty of this technique is that you can re-tweek it if your first kick attempt is off a tad. You only trim for final fit after you're satisfied.

Sometimes you'll have to trim from both ends -- but so what ?
He is bending 4" conduit. I would allow a solid 8 or 10 man hours for a first time evolution on a new bender.
Yes, after that, we have all of the marks or can at least figure out he marks that last guy left on the bender.
I dont have a cordless 4" deep portaband yet but, Im working on it.
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Old 08-11-2017, 06:52 AM   #14
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I forgot all about the measure once cut twice method. Depending on what coast you're on or generational slang, this method may also be called the romper room method.

The RIGIDPRO app really needs an instruction manual. It will take a while to figure it out. It's very powerful.

The 90 with the kick function Is used when measuring your long leg first, like if you were trying to spin on a 90 with a kick on a long leg.

I would set it up as two separate bends for EMT. Set up the 90. Then set up the kick. This way all the measurements come from your short stub 90. You can stack as many bends as you want with this app. Even set up the last cut length.

You can even use it to check your math. Lay out all your bends on paper and then check it with the app. This way you're using the app for learning not just cheating, as some would call it.

There is the option to flip the bend if you set it up the other way, measuring your long leg first.
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Old 08-12-2017, 05:46 PM   #15
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Wow that is a really interesting app. But for me to want to use it I definitely need a tutorial, on it. What is green and yellow bar on the left hand side?https://ibb.co/exrAKv
https://ibb.co/j1x0Kv
From this screen here are the mark measurements where I would put the front of my saddle? Does the app do all of the calculations and adjustments for me or will I still have to add half of the pipe width? Doing the kick 90 as two bends seemed to definitely give measurements that made more sense. I think I will contact the developer and play around with it from time to time, but until I figure out how to use it I will do the math my self, so after I bend the 90, I would do the math to figure out the hypotenuse I would then add half the width of the pipe and make that the Point at which I put the front of my saddle correct? thanks
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Old 08-12-2017, 05:49 PM   #16
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You cannot learn to bend conduit either on a forum or from a book.

You need to practice and practice, make mistakes then put them right with a mentor watching over you.


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Old 08-12-2017, 06:08 PM   #17
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I agree but sense my bosses do not understand the proper way to bend kick 90's and then teach me, I am having to figure it out, all the while not having a scrap pile. So when doing the math and measuring by hand what are the steps I do after I have bent the 90? I am using the greenlee881.
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Old 08-12-2017, 09:04 PM   #18
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Quote:
Originally Posted by platypuselectrician View Post
Wow that is a really interesting app. But for me to want to use it I definitely need a tutorial, on it. What is green and yellow bar on the left hand side?https://ibb.co/exrAKv
https://ibb.co/j1x0Kv
From this screen here are the mark measurements where I would put the front of my saddle? Does the app do all of the calculations and adjustments for me or will I still have to add half of the pipe width? Doing the kick 90 as two bends seemed to definitely give measurements that made more sense. I think I will contact the developer and play around with it from time to time,

From your first picture the conduit representation on the left is green because you haven't loaded the bend yet. It is still editable.

Your second picture, the bend is loaded, and now turned yellow. You can go back and edit it by swiping the bend to the left. Right now your bend is impossible because the first bend mark is not even on the conduit. Mark 1 is at -5 1/16". Because the kick is is the first bend and then the 90, it would be hard to bend this way. Also the leg after the 90 is the rest of the conduit. This is what happens when the bend is set up in one shot instead of the 90 first, then the kick. After the bend is loaded, you can press the conduit tab on the bottom left and flip the conduit in the bender and it will recalculate the bend the other way.

All the Numbers the app gives you for bend marks are from the start of the conduit. So you would hook your tape measure on the conduit and make all your marks.

The bend you described in your first post is also not possible, because the hook on the bender would have to be on the 90. You can see that with the second black bend mark on the yellow bent conduit of the 90.

In the screenshot you can see the 90 is loaded (yellow) and the kick is still being added (green).
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Last edited by cabletie; 08-12-2017 at 10:37 PM.
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Old 08-12-2017, 11:00 PM   #19
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so after I read you reply like 10 times and played with the app I think I understand it now, but I would like to confirm that I understand it. Also I would not have to do any other math, right? https://ibb.co/h504wa
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Old 08-12-2017, 11:01 PM   #20
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Quote:
Originally Posted by platypuselectrician View Post
https://ibb.co/exrAKv
https://ibb.co/j1x0Kv
From this screen shot here are the mark measurements where I would put the front of my saddle? Does the app do all of the calculations and adjustments for me or will I still have to add half of the pipe width?
Yes the marks given are to the front of the saddle because you have the 881 bender loaded. Load a bender like the 884 and it would give you marks to the center of the bend, because that's the benchmark.

You have options after a bend is loaded by pressing the conduit tab at the bottom. Here you can change where you took the measurements from e.g. To center of exsisting bend or start of conduit, where you want your bend marks e.g. Front of hook or center, and to flip conduit in the bender.

Everything is accounted for and it gives you the marks on the conduit for you to put your benchmark. Or even cut your conduit first before bending if you added a cut mark where you wanted your conduit to end.

You can also text or email your Bend to your partner while you continue to work.
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