Calculating kicks and offsets with factory bends

[grasfulls]

Layout of attached elbows

Layout of attached elbows

I see, so if I put two factory 30 deg kicks together, and measure the offset to be 4 inches, then I need to deduct the centers of bend from each kick to the end of fitting. So in the above example, with an offset of 4 inches, the center to center on the kicks should be 8 inches, cosecant of 30 being two, which is my hypotenuse. So if I want a 12 inch offset, I would have to cut a 16 inch nipple. But again, my problem was with the kicked 90. I,m just not sure how to do the math correctly for making a kicked 90 with a factory 30,a nd factory 90, other than laying it out on the floor or wall as I am being told. Thank for everyones help here.

I got lost, sorry. Your first post said "a factory 30 deg kick attached a factory 90," but now 2 ea 30 deg? Do your elbows match the attached specs (page2)? A factory 2.5" EMT 90 is 16", no? How do you get 14.5" with a 30degree elbow attached? Can you draw it for us?
thanks!

 

[Smart $]

... not sure what shape your raceway is trying to end up at...

Same here. :blink:

Are we talking a single 30° kick in the run or two 30° kicks back to back to make up an offset?

Are all bends in the same plane or not? Example of latter: 30-bend lays flat, 90-bend is a stub up (i.e. vertical)?

 

[ADub]

Same here. :blink:

Are we talking a single 30° kick in the run or two 30° kicks back to back to make up an offset?

Are all bends in the same plane or not? Example of latter: 30-bend lays flat, 90-bend is a stub up (i.e. vertical)?

He's using a 90° elbow and a 30° elbow to achieve a kicked 90° bend. It got way more confusing than it needed to be.


Sent from my iPad using Tapatalk

 

[wwhitney]

Hello all! used a factory 30 deg kick attached a factory 90, and measured. Stub height measured 14 1/2 inch. I needed a 28-1/2 inch kick, so I cut a 14 inch nipple and then measured, (14-1/2+ 14= 28-1/2) my kick ended up at 24 inches to bottom.

I have no experience with bending, but one thing I can tell you is that what you are doing is going to follow a linear proportionality.

So if I understand correctly the measurement you started with is 14.5", adding 14" somewhere changes it by (24 - 14.5) = 9.5," and you want to change it by (28.5 - 14.5) = 14". That means your 14" addition got you (9.5 / 14) of the way there, so instead of a 14" addition, you need to add 14" * (14 / 9.5) = 20.63" or 20-5/8".

This is assuming that your figures for additional length are totals including any added run from couplings.

Cheers, Wayne

 

[iwire]

I have no experience with bending, but one thing I can tell you is that what you are doing is going to follow a linear proportionality.

So if I understand correctly the measurement you started with is 14.5", adding 14" somewhere changes it by (24 - 14.5) = 9.5," and you want to change it by (28.5 - 14.5) = 14". That means your 14" addition got you (9.5 / 14) of the way there, so instead of a 14" addition, you need to add 14" * (14 / 9.5) = 20.63" or 20-5/8".

This is assuming that your figures for additional length are totals including any added run from couplings.

Cheers, Wayne

I do have experience with bending and while you are working on those numbers I will have laid the pieces out on the floor in the orientation I need them and measure the distance(s) needed with a tape.

The level of precision needed to do decent looking electrical piping is fairly low.

 

[wwhitney]

I do have experience with bending and while you are working on those numbers I will have laid the pieces out on the floor in the orientation I need them and measure the distance(s) needed with a tape.

I'm sure that's true, and I've done the same with plumbing.

I was just surprised that no one else had provided the OP an approximate answer, since it can be calculated from the information given. But I guess learning the method for measuring that you suggest will be more useful to the OP in the long run.

Cheers, Wayne

 

[tld38]

Factory kick calculations

Factory kick calculations

Thanks Tapatalk. Got it! Thanks to all who contributed to helping me here.

 

[ADub]

I'm sure that's true, and I've done the same with plumbing.

I was just surprised that no one else had provided the OP an approximate answer, since it can be calculated from the information given. But I guess learning the method for measuring that you suggest will be more useful to the OP in the long run.

Cheers, Wayne

I gave the op an exact answer based on standard trig formulas used in bending conduit. I feel like I'm taking crazy pills reading some of these posts haha


Sent from my iPad using Tapatalk

 

[Smart $]

He's using a 90° elbow and a 30° elbow to achieve a kicked 90° bend. It got way more confusing than it needed to be.

Like this...

 

[iwire]

I don't know exactly what you're asking but I know what you need, a 28.5" kicked 90 with a 30° kick. To achieve that all you need to know is you need 57" between the center of the 90 and the center of the kick, this fact doesn't change regardless of pipe size or the sloppiness of your factory elbows.

He was asking for the length of the nipple he needs between the factory 30 and the factory 90

So yes, you can start with that 57" measurement you provided but he has to deduct what he has already, the 90, the 30 and how much the couplings take up.

So for me this is much faster to do with labor then with figures.

Not saying your way is wrong or bad, just different than how I would approach it. Like most of our trade, there are many right ways to get something done.

 

[ADub]

He was asking for the length of the nipple he needs between the factory 30 and the factory 90

So yes, you can start with that 57" measurement you provided but he has to deduct what he has already, the 90, the 30 and how much the couplings take up.

So for me this is much faster to do with labor then with figures.

Not saying your way is wrong or bad, just different than how I would approach it. Like most of our trade, there are many right ways to get something done.

I would use labor as well but first simple math to determine the 57" figure. Just an opinion but I've never really enjoyed using factory bends for this very reason, too much work


Sent from my iPad using Tapatalk

 

[wwhitney]

I gave the op an exact answer based on standard trig formulas used in bending conduit.

The OP still seemed to have a little trouble with your answer, so I thought I'd show a different way to approach the problem, which directly yields the length to cut the nipple.

Cheers, Wayne

 

[kwired]

The engineer or like minded individuals will calculate it, the average field electrician will lay it out and measure it.

Both will get it right sometimes and will both be wrong other times on first attempt, you only need to miss one little detail either way.

 

[rambojoe]

always keep the stickers going the same way on pre fab stuff, itll be more accurate...

 

[don_resqcapt19]

The OP still seemed to have a little trouble with your answer, so I thought I'd show a different way to approach the problem, which directly yields the length to cut the nipple.

Cheers, Wayne

But your number does not match the number that others came up with using the standard multiplier of "2" that is used for 30° bends.

 

[wwhitney]

But your number does not match the number that others came up with using the standard multiplier of "2" that is used for 30° bends.

Yeah, I noticed that. But the OP's numbers didn't match that multiplier either: he added a 14" nipple, and his kick moved 9.5", not 7". Mostly I wanted to point out that if you are going to do it by trial and error, you can scale your initial result to get your desired result.

As to why the OP's observed multiplier wasn't 2, then either his factory bend wasn't 30 degrees, or he was doing something else weird we don't understand. Of course, if his measurements weren't accurate, all bets are off.

Cheers, Wayne

 

[Carultch]

lay the stuff out on the floor, and measure what you want to have happen.

most "factory 30's) etc. aren't thirty degrees, so formulas won't help you a lot.

If "factory 30's" aren't really 30 degrees, how do you figure out what they really are, prior to buying them?


Is this like a manufacturing tolerance thing, where a "factory 30" could be anywhere from 29 degrees to 31 degrees? I would expect that they would at least be built to a nominal average of 30 degrees among the fabrication of hundreds.

 

[ADub]

If "factory 30's" aren't really 30 degrees, how do you figure out what they really are, prior to buying them?


Is this like a manufacturing tolerance thing, where a "factory 30" could be anywhere from 29 degrees to 31 degrees? I would expect that they would at least be built to a nominal average of 30 degrees among the fabrication of hundreds.

I think the difference is negligible. I've never measured a factory elbow but there's no way they could be off enough that standard formulas wouldn't get you close to what you need. Any decent mechanic could figure it out without beating them self up


Sent from my iPhone using Tapatalk

 

[Carultch]

I think the difference is negligible. I've never measured a factory elbow but there's no way they could be off enough that standard formulas wouldn't get you close to what you need. Any decent mechanic could figure it out without beating them self up


Sent from my iPhone using Tapatalk

That's what I figured.

I guess the way that the person stated "factory 30's aren't really 30 degrees", made me question that there might be a systematic difference between the nominal 30 degrees and the actual bend angle. Similar to how a 1" conduit isn't really 1" in either ID or OD.