Surface split

[kbro151]

I'm trying to cut a hole in a large tube section. The hole is u-shaped and located on the edge of the sectino, extending about 1/10 radian along the circumference, and it has radiused corners. I've been able to generate the geometry of the edge of the hole fairly easily, including the corners, and am very pleased with the result.

My problem is that I used the surface that I want to split to make the edge of the hole, and when I try to split the surface I get an error that says 'Extrapolate a wire body: Extrapolated wire body is invalid due to self intersectinos. Modify the wire body or the input used to generate it.'

To create the wire body I intersected planes with the tube, extracted the geometry I needed, then formed my corners on the surface, trimmed the excess, and joined the resulting segments. How should I proceed so that I can get my hole?

 

[slcad]

How do the boundaries of the splitting surface look like?

 

[kbro151]

Hmmm....I don't have a surface. I have a wire on one surface, so it is just a line. Is that my problem?

When I intersected the planes and the extrusion I wound up with three surfaces, but I couldn't figure out how to join them into a single surface with a radius at the corners.

 

[Albigger]

Can you post a picture of what you're trying to do?

I usually get they error you are receiving when I'm trying to split something, and my splitting element does not cut across the whole element I'm trying to split.

--Jay

 

[kbro151]

Jay-

I'm lousy at posting pics. I might figure it out eventually, but currently that's beyond my capability. Anything I can't cut or paste into my browser doesn't make it onto the web.

The splitting element does not cut through the element I am trying to split. It lies upon one surface.

 

[Albigger]

I think I may be interpreting your post wrong, but this is what I'm envisioning (see image):

http://img239.imageshack.us/img239/3766/tubeuk8.jpg

Anyway, I still think you have a boundary issue somewhere. It's just hard to tell where or why without seeing it.

--Jay

 

[kbro151]

jay,

That's quite close to it. Now, add a right hand coordinate axis on the near end of the tube with y pointing radially up, x pointing radially out, and z along the axis. Make the tube a quarter section in the first quadrant. That's my extrusion.

Now instead of intersecting the u-shaped surface perpendicular to the x-axis, put in three planes that form a U. Intersect them with the tube to get three lines. Now put the corner radii in on the surface, so that if you were to unroll the tube you would have constant radius arcs instead of ellipses.

 

[rgmidway]

What happens when you Extrude your wire into a surface and try the Split (making sure the new surface boundaries are all clear of the tube...might require an Extrapolate or two)?

I also get that error usually when I need to extend my surface edges beyond the body I am splitting...like Jay said.

 

[jackk]

kbro151 (Aerospace) 21 Dec 06 15:12

I'm lousy at posting pics. I might figure it out eventually, but currently that's beyond my capability. Anything I can't cut or paste into my browser doesn't make it onto the web.


Kbro,

Kapitan posted the following instructions on how to attach images. (I printed his post and have referred to it many times) A picture would help everyone understand exactly what you're trying to do, and might get you some more advice.

http://www.eng-tips.com/viewthread.cfm?qid=127497