Rhino 9 Wip: Shell Command Improvements?

Rhino Rhino for Windows
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I’d like to know if the Shell command in the WIP version of Rhino 9 has been improved.
I’m posting an example of a Shell that fails in Rhino 8 (hollowing out by eliminating the flat base).

Another shell failed.3dm (327.4 KB)

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Hi Davide -
Shell is not one of the commands that was worked on for the WIP.
I’ve added this failure sample → RH-93612 Shell: Failure Sample
-wim

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Thanks

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Another example of a failed shell.
If the profile offset works, why shouldn’t the shell work? The principle is similar…

shell failed x.3dm (317.2 KB)

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fwiw, in lieu of a proper nurbs shell tool this alternate work flow does in fact allow you to shell anything very reliably.

and this one if you want to dig deeper

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There are other ways to do what I’m looking for (a shell), but it’s clear that the precision of NURBS modeling is lost, or am I wrong?

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Depends on what resolution you need for the b side. for the work I do regularly (toys and consumer product design) , we want less detail on the b side, so it works great for my needs.

Your mileage may vary-

if you crank up the resolution for the shrinkwarp offset you can get something pretty accurate, but there is certainly some loss in the shrinkwrap/quadremesh/subd/nurbs operation.

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Using Shrinkwrap as a substutute for precise NURBS surface shelling assumes that one is not going to work on the inside anymore to add details, modify things later, etc. - which is often the case. Essentially what one has after shelling using Shrinkwrap is a half-dead part.

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In fact, a shell that works better would be needed, not only in simple cases. To have taken this instrument out of the magic hat and left it as it is, without improving it, does not make much sense. I hope the developers will pay attention to this command, as well as to the surface blend and match surface.

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These are the most important NURBS modeling tools, yet they received nearly zero love since Rhino 6. Rhino 7, Rhino 8, and now Rhino 9 WIP didn’t offer any meaningful improvement.

Rhino 4 added adjustable handles for “Blend surface”. That was a nuch needed upgrade.
Rhino 5 or 6 added support for History to “Blend surface”.
If memory serves me right, Rhino 6 added “Interior shapes” option that does not work most of the time due to a bug related to point weight and surface degree (even the simplest possible input flat surface disables that option and causes adding of unnecessary amount of control points).

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These examples will fail in an application with more robust shelling. Have you tested these cases outside of Rhino? Often it is necessary to modify the geometry to achieve the desired shelling thickness regardless of the application.

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SolidThinking had a robust shelling some 15 years ago. It was class-leading at the time, along with the best history-based editing and best region deformation editing tool in the industry (a technology similar to Rhino’s UDT).

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The acute angles on these objects are one problem. I applied a small fillet and was able to get a successful shell on one object. However, the radius of curvature on some fillets built into the other object is smaller than the desired thickness. This is a common fail in shelling and can be overcome in some cases by not generating the fillet initially, then apply a fillet to the exterior and interior corner after the shelling. The fillets probably will not be concentric in that case. This may not be a good solution based on the manufacturing method. So the manufacturing method may be the real limiting factor, aside from the failure of the shell. DFM must be considered in the design process.

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not necessarily true. (tell me you didn’t watch the shelling video without telling me you didn’t watch the shelling video :wink: )

you can shrinkwrap offset to create the shell core, then quadremesh then tosubd then tonurbs and actually get a nurbs result. you then do a nurbs boolean and end up with a 100% nurbs result.

it is a long way round? yep…

does it work a treat and give you a really nice core?

also yep.

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I explored this couple weeks ago, so many possibilities!

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