Sectioning swept analytic arc not outputting analytic arc

[PrintScaffold]

Greetings all!

I'm experimenting with sweeping arc-shaped sections along the free-from guide. I found the following - even though the swept section is an analytic arc, I cannot get analytic arc if I slice the resluting body parallel to the initial section. Is this as designed? Is it possible to somehow build a body which will yiled analytic arc if sectioned as described?

The example model is attached to the message.

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[JohnRBaker]

YES, it's working as designed.

You can only get an analytic section if the FACE of the swept body is also 'analytic'.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
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[Xwheelguy]

John,

Would there be a way a user could anticipate an analytic result using Sweep by using certain curve types as sections or guides or specific choices in the Sweep dialog that would give the user what he desires? Is there just too much approximating (model tolerance) involved?

Thanks!

Tim Flater
NX Designer
NX 8.0.3.4
Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB

 

[Toost]

Tim, I think we can guess these results ourselves,
If we sweep an arc such that it scales, deforms etc it will not be analytic.
Analytic shapes ( from arcs) are limited to cylinders, cones , torus and maybe some shape which i have forgotten.
the S-shape in the original post is quite non-analytic , where NX instead uses B-surface math.

Regards,
Tomas

 

[Xwheelguy]

Tomas,

I understand your train of thought in regards to scale and deformation, but say I have a section made up of lines and arcs and try to Sweep along an S-shape guide that is also arcs and I'm expecting to get a nice, clean solid with analytic faces (for my drawing)....well, sounds like I cannot "force" it to come out as such. So I'm left guessing as to which command is going to give me the results I need.

Sweeps are quite powerful and result in some very intersting freeform shapes, however, I rarely use them for just this reason - I have no clue how to anticipate what a given section might end up being when I need to show it on my drawing. I need that Sweep, but I'm more than likely going to end up using a few Extrudes, a couple of Trim Bodies and some Edge Blends to get what I'm really after. It just may be the nature of the command...or maybe it's a simple mathematical rule (i.e. if you sweep an arc along an arc, you're going to get a B-Surface). Something along those lines, I feel, is what will help the OP more than anything.

Tim Flater
NX Designer
NX 8.0.3.4
Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB

 

[cowski]

There are a few exceptions, but generally the swept command will output a B-surface. If you need analytic surfaces, do NOT use the freeform surfacing commands.

Side note: in the example file given, even if the surface had been analytic, the section curves cut would still be splines (or at best ellipses) because the section wasn't cut perpendicular to the path.

www.nxjournaling.com

 

[PrintScaffold]

because the section wasn't cut perpendicular to the path.

There's more than meets the eye. The sweep was set up so that section would remain always perpendicular to the vertical spline, thus theoretically there was hope it would be analytic.

Industry creates wealth!

 

[JohnRBaker]

I think you'll find that by definition, any combination of profile curve and path curve types used when creating a 'Variational Sweep', will result in non-analytic face(s).

BTW, if all you're looking for are arcs, you could use the Simplify Curve function which will fit Arcs to a Spline. Note however that this function does not yet produce associative output.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PrintScaffold]

Well, the issue described in the original post is not critical. I just wanted to make sure I'm not missing something.

Industry creates wealth!

 

[Xwheelguy]

PrintScaffold,

As a workaround, I would suggest Extruding the section without any arcs in a straight path(square the shape and make it tall enough to pass completely through the guide paths). Then Extrude 2 profiles (which would be the guides in a Sweep) that can be used as Trim Body surfaces and cut the upper and lower portions of the solid away. Finish it with either 3 Faced Blend or 2 Edge blends...see if that gives you what you were after. If you're using splines as the S-shape, then you'll probably still end up with B-Surfaces.

Tim Flater
NX Designer
NX 8.0.3.4
Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB