Surface Oddity

Rhino Rhino for Mac
1

In the attached, I am fixing a shell that does not turn out solid.

I have extracted the problem area and started to manually repair (LEFT), leaving one gap at this poiint.

At the center I have tried to do EDGESRF on the opening. When I join I get a bad surface.

At the left, I have taken advantage of the symmetry and have done LOFT from the sides. That joins without an error

ViewCapture20231008_182723
ViewCapture20231008_1827232064×1616 280 KB

Problem Surface.3dm.zip (224.2 KB)

2

turn on isocurves (properties window)
the bottom surface is planar within document tolerance - build it like this - including the gab-area.
_planarSrf
_cap
can do this job.

for the curved surface inside the rectangle - build it as an trimmed extrude - avoid those pointy - collapsed edge faces.

my guess: both points above will help for better _offsetSrf and _shell

3

The bottom of the original was created using cap. This s just the offset created by Rhino (except for the three bottom surfaces). The entire bottom, including the “planar” surface, created by shell were caca. So I extracted all three and deleted and was trying to patch the hole when I encountered this oddiy.

Let me add another oddity here. The solid here take several steps.
Loft/Cap
Intersect
Fillet
Intersect
WireCut
Now shell.

The result will shell without error IF and ONLY IF I do a ShrinkTrimmedSrf at every step.

Loft/Cap
ShrinkTrimmedSrf
Intersect
ShrinkTrimmedSrf
Fillet
ShrinkTrimmedSrf
Intersect
ShrinkTrimmedSrf
WireCut
ShrinkTrimmedSrf
Shell. ! WORKS

On the other hand

Loft/Cap
Intersect
Fillet
Intersect
WireCut
ShrinkTrimmedSrf
Shell ! FAILS

4

How can we help ?
Is this a bug report ?

can you please specify the differences of the 3 surface-clusters in your file more precisely:

  • what are the difference in making them?
  • where is the input surface before offset / shell ? (did I miss it ? it s not in the file ?)
  • what is the offset / shell distance ?

maybe use _text _dot or other annotations in the rhinofile to link your question to it.

did you check document tolerance compared to size of details and offset ?
did you check edge tolerance ?
→ seams ok
Edge Tolerances: 0.0000 to 0.0008
median = 0.0001 average = 0.0002

not sure what exactly is the difference between the 2 worksflows above (ShrinkTrimSrf many times / once) - are the results in the document ?
_explode
_untrimAll
to compare them ?