10 Replies Latest reply on Jul 20, 2011 10:10 AM by Charles Culp

# Perpendicular surface along midpoint of existing surface

Hi all,

Is there a way to create a surface that would be at the middle of a surface (referencing two edges of the surface) and also perpendicular to it?  For example, if I had a flat surface that was 6mm wide, I could create a perpendicular, ruled surface along one edge and then offset it by 3mm, but what if the surface varied in width.  Trying to do this without sketching.

Thanks!

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Are the two edges straight (but not parallel), or are they curved/wavy?

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In this case they are curved.

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Would be nice to be able to use the face curves that can be found in the Freeform command.

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Alin, Brilliant!

I've been pondering this question for a long time. Alin's insight has helped me to find an answer, see attached. This will be directly useful to a side project I will be working on later this week, so I'm pretty happy.

Create a 3D sketch, and use the "face curves" tool to automatically generate that centerline. The trick is I first created a Surface Fill for the face, to force the NURBS patch to conform to the existing edges, any other tool seems to create a square patch and then trim to fit. This would not be true for a non-planar face.

So you had a requirement of "no sketches", but does that really just mean that you want it to be parametric and automatically generated? I think my model does that.

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Face curves, of course! Good one Charles. Too bad that when you apply them directly to a face of a solid, you get them in an orthogonal format.

They work fine with surfaces, as you discovered.

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Alin, Charles is correct in that your face curve prompt was a good one.  Charles, you beat me to what I was going to do with Alin's comment.  That is a wonderful way to go about what is normally a bit of a pain.  I think you know what I am referring to with "no sketches" (the ones that define the center position, usually a perpendicular set of curves) and of course this takes care of that.

Thanks both.....but I'm afraid the correct answer will have to go to Alin on this one as I think you might agree Charles.

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Here is what I did just using surfaces.  Any objections?

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Interesting approach, Mike. To increase the precision even further, you might want to avoid creating a second lofted surface. Use the original surface instead as a reference for the ruled mid-surface.

For that:

1. Make a copy of the original surface body

2. Trim the new surface with the 3DSketch containing the mid-surface curve

3. Add the ruled surface on the newly created mid-edge

4. Feel free to delete the copied surface body

This way all references are taken only from the original surface and not from a lof approximation.

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Alin, thanks for the prompt.  I initially tried trimming the original surface with the 3d sketch, but I was in a hurry and as it was defaulting with a mutual trim, I didn't think it would allow me to trim with that 3d sketch.  But obviously it will once you get the correct trim type......

Thanks again!

• ###### Re: Perpendicular surface along midpoint of existing surface

Mike,

That is the method I tried first. With my model, because the face generated was flat, it still created a trimmed surface. In your model, because it is non-planar, it actually creates the surface. Thus that is the method I would want to use. Looks good to me.