How to find arc length

[Anonymous]

Hi,

Im struggling to find 2 lengths of an arc. See attached.

I have tried so many things now to find it, but now i will ask here to get the problem solved.

I need 2 lenghts for the arc, before the pipe is bent and when it is bent ( like you see in attached drawing)

Can someone show me how to find these 2 lenghts for the arc ?

Some really good guy from this forum,helped me with the attached drawing.

Hope there is one more to help me with this 🙂

[j.palmeL29YX]

Here you go.

If my reply solves your problem, click the "accept as solution" button. This can help others find solutions faster

[Anonymous]

Im not sure that i understand your figure. I guess its millimeters.. How did you calculate it?

And how can the difference be so big? 

[mdavis22569]

Is this what you're looking to do? 

If it's not meant to be this big you might need to scale it down.

[mdavis22569]

https://knowledge.autodesk.com/community/screencast/48f6d821-d9d7-47c2-84dc-41f2c480a789

[Anonymous]

Hi,

Thanks, but can you show it with my file which i attached ?

And i need the length of my pipe before it is bent (straight paipe)

and after it is bent ( as you see it at my attached file)

[Anonymous]

Hi,

Thanks, but can you show it with my file which i attached ?

And i need the length of my pipe before it is bent (straight pipe)

and after it is bent ( as you see it at my attached file)

[mdavis22569]

That's something different than ARC length ...

[Anonymous]

Ok pipe length 🙂

[Anonymous]

Should i create a new message then with pipe length instead ??

[j.palmeL29YX]

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@Anonymous wrote:

Im not sure that i understand your figure. I guess its millimeters.. How did you calculate it?

And how can the difference be so big? 

---

First as I read your posting I was irritated: "I need 2 lenghts for the arc, before the pipe is bent and when it is bent". 
IMO the length of a bended pipe and the unbended pipe are theoretical the same (notwithstanding small deviations).
But after looking at your model I saw, you have a 180° bended pipe and than trimmed (splitted) about 1600 at each end. 

" i need the length of my pipe before it is bent (straight pipe)

and after it is bent ( as you see it at my attached file)" 

I can not find in your file a staight pipe ... ?? What do you mean? 

So I think you mean the difference between the unsplitted and the splitted pipe. 

The length of the unsplitted pipe can be calculated easily by
6150*PI/2 -> 9660.4 (as shown in my image above).
If you snip (a little more than) 1600 at each end, then the length of 6294.8 seems to be plausible. I didn't calculate it, but created a drawing and added the dimension of the lengthen of the arc (centerline of the pipe).

If this is not what you are asking for, please explain which two lengths you want. If you want really the length of the inner and the outer conture as shown by @mdavis22569 , then you can find it yourselfe:
- create a new .idw
- create a view at your model
- mark the view (it must be selected)
- add a new sketch
- add the dimensions (choose the dimension type "arc length")
=> you will find the lenghts 6376.52 and 6219.77
But I can't believe that this is your intention (?) 

Perhaps you posted the wrong file?

HTH

[j.palmeL29YX]

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@Anonymous wrote:

 I guess its millimeters..

---

... and yes, it is in millimeters. Because I'm sure the source drawing also was drawn in millimetres. The Workplane was moved 1600 mm = 62,99212598 in. What is more plausible?

[Anonymous]

Half of the circumference of the circle  is not equal to the length of my pipe.

Its approximately  a third of the circumference of the circle with diameter D=6150 mm (calculated with centerline of pipe).

Have you seen my .ipt file in Inventor ?

I can easily calculate the lenght of the pipe, when drawing it on a piece of paper, by measuring angles and so on, but im not very used to Inventor, so would like to see how i can do it in Inventor, to get a more precisely result.

[Anonymous]

yes i think its as shown by @mdavis22569 .

What i have calculated is close to his results.

But its really difficult for me to see what he is doing..

If you can do it with my file i guess i can understand it.

I have to construct this pipe so i need to know the length of the pipe i have to put into the tube bender, and teh tube bender machine needs a .ipt file to do it 🙂

[j.palmeL29YX · Accepted solution]

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@Anonymous wrote:

... would like to see how i can do it in Inventor,  to get a more precisely result

---

>>Here<<  you go. 

But - it is not more precise than the other proposals made above (They all are precise and you see again the same correct result as above). Of course you can still increase the visible number of decimals ...

[Anonymous]

And why cant  you believe that this is my intention ?

In a working process to bend a tube, i guess i need the lenght of the tube ?

[Anonymous]

Yes thanks, now i understand and can see what you are doing 🙂

Dont you think its needed with this length to construct  the pipe ?

I guess that the tubebender machin needs this information, or is it a more normal process to feed the machine with for example 7000 mm of pipe, and then cut what is to much of subsequent ?

[j.palmeL29YX]

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@Anonymous wrote:

... or is it a more normal process to feed the machine with for example 7000 mm of pipe, and then cut what is to much of subsequent ?

---

I would strongly recommend to do so - use a pipe which is too long and after bending cut what you don't need.

This is, because the calculated or constructed length is a theoretical value, assuming the bending is exact along the centerline of the pipe. But in reality the bending line is a little beside the center line (depending on Material and a lot of other factors) and so you need another length of the pipe than the calculated. 

[Anonymous]

Thanks, I really appreciate your help ! .-)

[Anonymous]

Hi again,

Can you do so i can save your .ipt

file ? 🙂

Right now it is a screen cast..

Its difficult for me to follow these videos because i cant always find what i need to.