Hollow varied taper tube on a spline

[TheManWithBlorns]

Hello,

I need a little advice on a few design problems I have, please.

I need to create a tapering hollow tube that follows a spline. The taper is not constant but varies along the full length. (Picture below is similar to what I am replicating) 

Q1: Is it possible to first draw the taper end-to-end along a single plane, allowing for accurate design of the taper, then attach it to a spline drawing?

Q2: When creating a varying/curved taper tube, what is the correct method for this? The "wall thickness" will be the same the entire length and I'm sure there's a simple way to do this.

Any help is welcomed

[g-andresen]

Hi,

Please share the file. 

File > export > save as f3d on local device  > attach it to the next post.

günther

[TheManWithBlorns]

Hello,

Here is a test file including the model and the curved spline.

[g-andresen]

Hi,

play around a bit with this principle

günther

[g-andresen]

Hi,

here ´s a screencast

günther

[TheManWithBlorns]

Hi,

Thank you. But how do I best translate accurate taper dimensions using this method?   If, for example, I was trying to translate the exact dimensions of the example Model to the spline?

[g-andresen]

Hi,

this way

or calculate via angle functions

günther

[TheManWithBlorns]

Hi,

But if the taper is an inconsistent curve that varies across the full length I can't see an appropriate way. I could create hundreds of Diameter circles, say every 0.5mm spacing, along the spline and loft between them but that seems like a long overly complex way of doing it.

[davebYYPCU]

2 Revolves, then centre line Loft to join them.

Might help...

[TheManWithBlorns]

That's my issue; I can do that but that doesn't work well for a taper that is not constant along the length. The taper is mostly curved and more "steep" of an angle in some lengths than others.

I would have to create many circles along the length according to the diameter as it changes and loft them all.

But there must be a more efficient way?

[davebYYPCU]

The loft is done with Planes on the path, circles on each plane, with spacing as suits - kept to a minimum of 3 or 4 - taper looks fairly consistent from here.  Photo is not the sames as your model.

[g-andresen]

Hi,

You must measure the stretched lengths for the individual sections and the corresponding diameters.

According to the example above, you then determine (calculate) the associated angles.

günther

[TrippyLighting]

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@TheManWithBlorns wrote:

I would have to create many circles along the length according to the diameter as it changes and loft them all.

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That is not the case, you might want to take measurements and compare those with the loft you create, but using "many" circles to loft is not going to result in a more accurate loft. That isn't how NURBS surfaces work! Less is more when working with splines and lofts.

A start and end circle and maybe one, or two in between should be all that's needed.

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@TheManWithBlorns wrote:.

But there must be a more efficient way?

---

See above.

[TheManWithBlorns]

The photo in the OP was just a reference as I didn't have a Fusion model at that point. I do now have a test model thanks to Guenther Andresen. 

The taper is not consistent along the full length for the end model I need to create as stated in the original post and subsequent posts.

[davebYYPCU]

Will shell, as required.

[TheManWithBlorns]

Let's say I had access to an original physical part and was able to map the diameter every 5mm around the full length.

If I were only to use 3-4 circles to loft from I would only be able to approximate the taper and diameters in between, no?

I'm just trying to pinpoint the most accurate way.

[g-andresen]

Hi,

What is stopping you from drawing or calculating the angle?

günther

[g-andresen]

Hi,

sorry, edit doesn´t work for me

günther

[TrippyLighting]

@g-andresen if the taper is not constant, then the angle isn't either?

@TheManWithBlorns WHile this would be a good bit of work, you can still measure horn diameters and place those into a sketch, but that sketch would only be used as a visual aid to approximate the shape.

If you measured the diameter of the horn every 5mm and loft through circles that way, that will NOT make this more accurate as the loft surface will suffer from curvature problems.

Ideally, provided the horn was designed and made this way the horn might follow a mathematical formula and associated parameterization of that formula. However, we don't know what that formula is and NURBS surfaces follow a different formula.

[g-andresen]

Hi Peter,

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@TrippyLighting wrote:

@g-andresen if the taper is not constant, then the angle isn't either?

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Where did I say that the angles are constant?

I wrote in one of my posts that you have to determine the associated angles for each sequence.

I used one of them (sequences) as an example in #18 for the explanation.

günther