Blend surface

Hi. I’m trying to blend two surfaces that I separated using offset and trim. When I’m trying to select the first surface it doesn’t select the whole loop while the other is selecting as a whole. Could anyone help me with what I might be doing wrong here? Thanks.

BlendSrf blends between two edges.

A single edge runs all the way around the opening of the outer cylinder. But the apparent “edge” of the inner cylinder is actually split into two Rhino edges. The reason it is split is because a cylinder in Rhino is a rectangular sheet rolled into a cylinder with a seam. A Rhino edge will not be continuous across a seam.

Two possible solutions:

A: Try using the ChainEdges option in BlendSrf.

B: Use SplitEdge to split the outer cylinder edge into two parts which correspond with the inner cylinder edges. The Quad OSnap may be helpful. Then use BlendSrf on the two sets of edges.

C: Untrim the inner cylinder. Use SrfSeam to move the cylinder’s seam so that it will not be on the trimmed part. Retrim the cylinder. Then use BlendEdge

Added note: It is frequently helpful if the .3dm file with the geometry in question is uploaded along with the screen captures.

jbl.3dm (175.6 KB)

I still don’t understand how to do it. I just started using the software. I have uploaded the file it might help. Thanks a ton.

Hello - see if this helps -

  • ChainEdges when selecting the edges to blend
  • Add Shapes and adjust them to true up the surface across the gap.


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Thank you so much. It was so simple. I was stuck for hours on this thing.

I like to break these blends into sections. I’ll use curves to set to perp, to set the split points of the surface edges. Position blend the surfaces. Then use match surface with preserve isocurve direction.