topic Re: Hollow varied taper tube on a spline in Fusion Design, Validate & Document Forum

Hollow varied taper tube on a spline

TheManWithBlorns — Wed, 07 Apr 2021 10:22:54 GMT

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

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 10:38:31 GMT

Hi,

Please share the file.

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

günther

Re: Hollow varied taper tube on a spline

TheManWithBlorns — Wed, 07 Apr 2021 10:57:26 GMT

Hello,

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

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 11:13:43 GMT

Hi,

play around a bit with this principle

günther

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 11:45:18 GMT

Hi,

here ´s a screencast

günther

Re: Hollow varied taper tube on a spline

TheManWithBlorns — Wed, 07 Apr 2021 12:25:54 GMT

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?

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 12:47:50 GMT

Hi,

this way

or calculate via angle functions

günther

Re: Hollow varied taper tube on a spline

TheManWithBlorns — Wed, 07 Apr 2021 12:56:56 GMT

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.

Re: Hollow varied taper tube on a spline

davebYYPCU — Wed, 07 Apr 2021 13:14:19 GMT

2 Revolves, then centre line Loft to join them.

Might help...

Re: Hollow varied taper tube on a spline

TheManWithBlorns — Wed, 07 Apr 2021 13:18:18 GMT

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?

Re: Hollow varied taper tube on a spline

davebYYPCU — Wed, 07 Apr 2021 13:26:25 GMT

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.

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 13:30:45 GMT

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

Re: Hollow varied taper tube on a spline

TrippyLighting — Wed, 07 Apr 2021 13:32:43 GMT

@TheManWithBlorns wrote:

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

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.

@TheManWithBlorns wrote:.

But there must be a more efficient way?

See above.

Re: Hollow varied taper tube on a spline

TheManWithBlorns — Wed, 07 Apr 2021 13:33:52 GMT

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.

Re: Hollow varied taper tube on a spline

davebYYPCU — Wed, 07 Apr 2021 13:38:53 GMT

Will shell, as required.

Re: Hollow varied taper tube on a spline

TheManWithBlorns — Wed, 07 Apr 2021 13:40:33 GMT

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.

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 14:14:23 GMT

Hi,

What is stopping you from drawing or calculating the angle?

günther

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 14:31:46 GMT

Hi,

sorry, edit doesn´t work for me

günther

Re: Hollow varied taper tube on a spline

TrippyLighting — Wed, 07 Apr 2021 16:50:52 GMT

@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.

Re: Hollow varied taper tube on a spline

g-andresen — Wed, 07 Apr 2021 17:08:36 GMT

Hi Peter,

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

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