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Control size of spline

Genius
Genius

Very sorry for so many questions!

 

I'd like to control the size of a spline (sketch) with two parameters -  width and height, while retaining its basic shape, just as in the figure below.

 

Spine scaling.png


What I want is to make both the width and the height of the spline adjustable separately. But it seems that, either with Uniform Scale or Non-uniform Scale contraints on the spline, only one of the two parameters can be adjusted.

 

It seems that Scale Curve does not help. And also I don't want to constrain point by point on the spline, since some splines may have >10 defining points.

 

Do I miss something? Or is it possible?

 

Thanks! 

7 REPLIES

Re: Control size of spline

Phenom
Phenom

mf_curv_20171124.JPGWill this work for you?

 

Michael Fernando


Die Designer
NX 11.0.2.7 + PDW

Re: Control size of spline

Genius
Genius

Hi, @mike_fdo

 

In your file, when p16 (height) is increased, only pole no.3 moves up, and but poles no.2/4 stay fixed. Then the "basic" shape of the spline is modified.

 

I hope that, when p16 (height) is changed,

 

  • the Y values of poles no.2/3/4 are changed by the same scale factor, and
  • the X values are fixed.

 

Thanks!

 

Re: Control size of spline

Phenom
Phenom

You could define the behavioral rules with sketchs, contrains, Formulae etc. :

mf_curv_20171124_02.JPG

Michael Fernando


Die Designer
NX 11.0.2.7 + PDW

Re: Control size of spline

Genius
Genius

Hi, @mike_fdo

 

In your "Spline control_mf_02.prt",

  • when p16 is changed, X values of pole no.2/4 are also changed.
  • And you try to constrain pole no.2/4, which means that you need to contrain all difining points/poles along the spline. When a spline have 10 or 20 defining points/poles, the job seems to be a little difficult.

 

Thank you!

Re: Control size of spline

Genius
Genius

Hi, @mike_fdo

 

I just find that:

 

  • the "Non-uniform Scale constraint" on a spline contraints the defining points/poles and always reparameterizes the spline when the start-end distance changes. And the final effect is far away from simple scaling. This can be seen clearly with the right part of the spline in figure below.

 

Image.png

 

Thanks!

 

Re: Control size of spline

Siemens Legend Siemens Legend
Siemens Legend

I would not do this in the sketcher.

NX 11 offers a great tool to scale any curve. Use the scale curve feature. You may need to play around to get nice input features to key in actual sizes instead of factors.

See attached part.

 

Johannes

Re: Control size of spline

Genius
Genius

Hi, @Johannes_H

 

Thank you for suggestion of Scale Curve feature!

 

My original goal is to use other objects and contraints in a single sketch to control the shape of a spline. In my plan, working in a single sketch would make the whole design, especially in case of many splines involved, much much easier to handle. It's very dissappointing to find that Scale Curve for Sketch does not help.

 

Using Scale Curve feature would require building some expressions to correlate the spline, scale factor and contraining objects. It seems to be a little sophisticated. But it seems to be the only way to accomplish the job. I would try it.

 

Thanks!