Trig bending conduit

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Ive been trying to brush up on my trig. Ive even googled, yahooed, hotbotted and everything trying to the info on trig that shows how to do it WITHOUT the calculator.

I know the formulas, A(squared) + O (squared) = H(squared) Thats the pythor (sp?) theorem.

then theres the Sine of the angle= O/H Cosine of the angle=A/H Tangent of the angle=O/A
etc.. Im not gonna write out all the formulas.

What im seeking is the way to find the angle WITHOUT using the calculator, I know the inverse of the tangent will give me the angle , but how do you do the INVERSE of the tangent by hand?? Thanks.

Oh by the way, i know you use the cosecant to bend conduit,, ie 30 degrees is 2 , 45 degrees is 1.4 etc.. Just trying to do my trig formulas
 
nakulak said:
stick to 22 1/2, 30, 45 and memorize the values
otherwise keep a calculator in your tool bag

doing it by hand is a complete waste of time (and time is money)
do you really want to sit there and take 30 minutes to figure out an angle by hand ? If you are that hard core, get an abacus.

http://mathforum.org/library/drmath/view/52576.html
Click to expand...


Just doing it for a brush up, I dont do this on JOBS!! LIKE YOU SAID TIME IS MONEY!! Also i already have those memorized.
 
brother said:
What im seeking is the way to find the angle WITHOUT using the calculator, I know the inverse of the tangent will give me the angle , but how do you do the INVERSE of the tangent by hand?? Thanks.
Click to expand...
Basically, you can't do it by hand, except for the special values that are known, like arctan(1)=45, arctan(1/sqrt(3))=30, etc. You could try estimating it by linear interpolation, e.g. since 1/sqrt(3)=0.5774, then arctan(0.7887) is about 37.5 degrees. The calculator tells me it is really 38.26 degrees, so that's not so bad.

You could try using the expansion of arctan as a power series about 0. That is, arctan(x) = x - (x^3)/3 + (x^5)/5 - (x^7)/7 + . . . If we take the first three terms of this series for the case of x=0.7887 we get 0.6862. That's in radians, so multiplying by 360 and dividing by 2*pi gives 39.32 degrees, which is surprisingly less accurate than our linear interpolation. So if you are going to do this, better use more than 3 terms! It would quickly get to be impractical.

One small note: either of these methods will work better for x < 1. So if you need to calculate arctan(x) for x > 1, just use the fact that arctan(1/x) = arccot(x) = 90 - arctan(x).

Yours,
Wayne (a former mathematician)
 
Well.....

Well.....

I have seen alot of people waste alot of time with trig and bending. Even though we don't all agree 100% on Benfield's technique, it is simple and efficient.

Trig on running pipe? Not my cup of tea:cool:
 
Im quite good at the art of conduit bending, but absolutly suck at trig....can't imagine why you would want to confuse such a simple mechanical art with crappy ol math!
 
Stong Math

Stong Math

Gezz whitney :grin: I got lost on x > 1 , x < 1, and that's me, but hey over all that was out of the ball park ...

I was going to touch a calculator, but I grabbed the ugly hanbook instead, Pg 147 Natural Trigonometric Functions

The simple act of finding the value can be quickly cross referenced there.

Recalling that he also was solving for the sides and a length. giving a solution of that means about nothing other then with the use of a
calculator or a Natural Trigonometric Functions-sheet to proof sides, etc.

Why they need this, other than, exacting lengths of exposed conduit maybe, I don't know!
 
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There's a pretty good conduit bending section in this book:

nfpa70fordummies.jpg
 
POWER_PIG said:
Im quite good at the art of conduit bending, but absolutly suck at trig....can't imagine why you would want to confuse such a simple mechanical art with crappy ol math!
Click to expand...


Like i said, i do not do this on jobs. I just like math, and was just brushing up. Believe it or not, using/visionalizing angles actually help me see how to do runs faster. Yes this crappy ole math actually helped on segemented/concentric bends and parrell runs.
In our apprenticeship, trig is required. Even though i will admit that i learned how to do most bends by just memorizing the multipliers before i ever took trig. ;)
 
Don't think anything in the NEC will help you bend pipe.... And Ugly's is "dummied" down enough for most of us - I think????

Anyway who needs math - 1/2 the time I dont even use a tape measure. As I can thumb & guess-timate most angles and measurements, and know a few ways to correct it if I'm wrong... :rolleyes:

Off-set not big enough - bend it bigger...
Off-set too big - roll it to one side....
90 stub too short - open the bend and move the bender back and re-bend.
90 too long - turn pipe around and do the same as above.
Bent wrong way - coupling....

Why start over when forward is the way to go?
 
e57 said:
Anyway who needs math - 1/2 the time I dont even use a tape measure. As I can thumb & guess-timate most angles and measurements, and know a few ways to correct it if I'm wrong... :rolleyes:

Off-set not big enough - bend it bigger...
Off-set too big - roll it to one side....
90 stub too short - open the bend and move the bender back and re-bend.
90 too long - turn pipe around and do the same as above.
Bent wrong way - coupling....

Why start over when forward is the way to go?
Click to expand...
I think all 14 of your brothers work for me. :grin:
 
here is the trig table I only use it when using a Chicago bender. That way I can use the benders stop to set my angles for offsets three full pumps is somewhere near 30 degrees some times a little less sometimes a little more. Using my protractor I find the angle then I go to the chart and find the coseccant and this the multiplier for offsets this really helps on large pipe racks where you want all of your offsets to match. http://www.industrialpress.com/en/tabid/63/default.aspx
 
e57 said:
Don't think anything in the NEC will help you bend pipe.... And Ugly's is "dummied" down enough for most of us - I think????

Anyway who needs math - 1/2 the time I dont even use a tape measure. As I can thumb & guess-timate most angles and measurements, and know a few ways to correct it if I'm wrong... :rolleyes:

Off-set not big enough - bend it bigger...
Off-set too big - roll it to one side....
90 stub too short - open the bend and move the bender back and re-bend.
90 too long - turn pipe around and do the same as above.
Bent wrong way - coupling....

Why start over when forward is the way to go?
Click to expand...

I hope all your conduit is in walls or drop ceilings. The only times I have ever needed the trig was when following cable trays to match the trays 90's. I sometimes use the largest bending shoe when running different sizes on a rack together so all the bends will have same radius. I also write the offset measurements and degrees somewere at the rack next to the bends so the next time we are adding conduit to that rack there is no trying to measure the center of bends.
 
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