Need help creating 3/8" thick pot with flat top

Rhino Rhino for Windows
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1

I am trying to make this object 3/8" thick with a flat top. This is for 3D Printing on a large format printer so needs a high mesh resolution. Offsetsrf makes it an open polysurface. Offsetmesh on this high resolution mesh works and creates a closed mesh, but then when i try to flatten the top, or Boolean difference the top, the mesh is open. How do i cut off the top nicely and create a closed mesh or close polysurface? Thank you in advance!!

planter 1
planter 11918×1002 129 KB

planter 2
planter 21918×1002 163 KB

PLANTER HELP.3dm (5.5 MB)

2

Hi Erica - the offsets do not intersect completely - that is, the offsets are sent downward by the angle of the surfaces and the extensions, to bring them back to the original level of the top plane, diverge-

image
image1074×604 90.4 KB

I’ll see if I can make something work.

-Pascal

3

Hi Erica,

If you can accept a thickness that varies a little over the surface rather than being 3/8" everywhere then here is one way to get a clean solid pot.

image
image1027×721 128 KB

  1. Take the nurbs polysurface and copy it to a new layer.
  2. Create a circle around the centre of the top hexagon on another layer. The circle should touch the vertices of the hexagon. Create a second circle with a radius 3/8" less.
  3. Hide the original layer for now.
  4. Sub-select the base of the new polysurface and delete it.
  5. Do a non-uniform scale on the polysurface to make it smaller. Use the circle centre as the origin and select the appropriate quads on the outer and inner circles to set the x, and then the y, scaling. Set the z scaling to 1.
  6. Trim 3/8" of the bottom of your slightly shrunken polysurface. You now have a set of inner surfaces. Close the bottom hole (simple way to do this is to cap planar holes and then sub-select and delete the top cap).
  7. Bring back the original polysurface. Creating a planar top surface using the planar curves option with all the outer and all the inner top edges. Connect the inner, outer and top surfaces with join.

That’s your solid pot.

One other thing you might want to consider. The surfaces you uploaded don’t give a particularly smooth render. To improve the appearance before you start building the solid pot you can extract the edges and change the degree of the straight top and bottom ones from 1 to 3, delete the original surfaces and build new surfaces from the updated curves.

HTH
Jeremy

4

Hi Jeremy, Thank you for all your help! I was able to follow your instructions and get a nice 3/8" thick pot with a flat top!! Although I was not able to get nicer smoother surfaces. Would you be able to list how to do that? I created that by lofting hexagons, pentagons and other shapes. Can the surfaces be made to be smoother in the lofting command?
PLANTER HELP.3dm (5.9 MB)
I have attached the shapes if you wanted to take a look.

5

Hi Erica,

Use _DupEdge to create curves from all the outside edges of your initial polysurface on a new layer and delete the polysurface:

image
image1027×738 74.8 KB

(Note: the new curves should not be joined if you do this. If they are then explode them so you can subsequently select just the top and bottom edges.)

Select all the top and bottom edges and run _Rebuild. In the dialogue box, increase the point count to 5 and the degree to 3. Make sure the Delete input option is ticked.

Select the four curves that bound a single face and create that face by using _EdgeSrf. Repeat for the remaining seven sides. Join the eight surfaces together and then add the bottom face.

That should be enough to get smooth surfaces in a render, rather than showing the artefacts in the original surfaces:

image
image1920×1378 45.6 KB

But try setting the point count to 4 or 7 and see how that affects your surfaces.

Why go back to the original curves and rebuild them when you have the option to rebuild a surface? Rebuilding these surfaces will result in surfaces that deviate from the originals appreciably. Rebuilding the curves selectively and then generating new surfaces avoids that significant deviation.

HTH
Jeremy

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6

Jeremy, I just wanted to thank you for all your help! I really appreciate it!

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