Help me Sweep! - modeling workflow puzzle

I am creating a Model of a Stone Lintel, that curves in two directions with a specific profile.

I am having quite a bit of difficulty getting Sweeps to line up so that
A. The Stone stays in the plane of the Brick
B. The Stone Creates a watertight Model.
C. The workflow makes sense.

Here is What I want:

To create the above, I swept two rails. This created a geometry that looked Nice, but the Sweep went outside the “brick Plane” and in order to get this image, I did a “cage edit” and pulled it back to my control line. However The “Cage Edit” also broke the clean bottom edge of the Geometry gets uneven.

If I just sweep 2 Lines, I do not seem to know how to tell rhino exactly what I want: a cleanly mitered edge/ or blend between these two surfaces.

How would you solve this geometry?
Sweep help.3dm (3.6 MB)

Hi Ben,

Sweep2 accepts more than one profile curves.
I’d position a second (copy?) of the profile at the ends of the 2 rails.

Does that make sense?


not sure if this is what you are looking for. I tried getting uniform space around the sweep. If it is I will try to get back to ya about exactly how I did it.Sweep help-drb.3dm (4.6 MB)

1 Like

Thanks All, willem was right, When I use sweep2, I the two profiles "loft"together, and you get clean lines. Thanks!

Perfect. Thanks! Which commands did you use to reach this result?

Willem was right and I copied the white line using transform 2 point scale 1D and created the second rail curve
trying to keep the same standoff and swept to sections.

1 Like

I deleted the small vertical section and lofted it to the edges and joined mirrored and had a solid

cheersSweep help-solid-drb.3dm (3.8 MB)

1 Like

Sorry for a lot of images.

First of all you have to decide what exactly you want to do. It looks like the top arc curves are elliptical, and not circular (an arc per se). Is it intentional?

For the arc I would offset the upper profile from the top view, so you know exactly that the top surface stays horizontal, and get rid of skewing.

Then project these two curves to c-plane, and orient the bottom profile to the ends:

Sweep the arc (it is a temporary sweep to get the profile).

You may need to adjust (rotate a little, and use a piece of projected curve to replace one segment) the profile to look more like this:

Sweep the bottom profile up, and get an intersection curve of the two shapes.

The intersection curve will help you build a surface on which to project the bottom profile (you draw a curve, snapping to the corners, extrude along the edge of one the the temporary shapes, and extend surface as needed).

Sweep help-0t.3dm (2.3 MB)

1 Like