Joining two tubular surfaces such that slopes are equal

Rhino Rhino for Windows
1

I’ve tried variable radius fillet, variable radius surface blend, matchsrf, blend, … all to NO avail. any suggestions on how to remove the slope discontinuity?

Art
intake port 03-01-2025.3dm (797.8 KB)

2

I’d use Pipe and create one surface rather than two surfaces. Make sure the centerline curve has the desired continuity. That result will be better than modifying what you currently have.

Your surfaces have seams in different locations which MatchSrf does not like. You can use SrfSeam to move one seam to match the other. (Added: See post below for an alternative solution.)

The surfaces are also “rational” in the circumferential direction which can cause difficulties with MatchSrf. RebuildUV the V (circumferential) direction of each surface to make non-rational, with the same number of control points in the V direction for both surfaces. (MatchSrf works better when the control points on the two surfaces align.) The result will be degree 3 non-rational surfaces. The rebuilt surface will deviate a very small amount from the original surfaces. I used 12 control points and the max deviation was 0.00014. (PointDeviation used to measure deviation.)

After revising the surfaces use MatchSrf and the result should have tangential continuity. (EdgeContinuity reports 0.00 degree continuity.)

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3

David-

Thanks for your note!! never would have stumbled to “seam location” as the source of my trouble

Art

4

Since my previous reply I realized a simpler way to remove the problem of MatchSrf with non-aligned seams and control points is to use the “Match edges by closest points” option.

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