algorithmic modeling for Rhino

Hi Guys

I need help with a rib builder I'm trying to build. I know there is the grillage fabricator out there but i want mine to behave a little differently. And i promise to share the definition once i've finished.

So my problem is;

I have divided the geometry in the x and y as curves. So i have these curves and i want to lay them out flat on a sheet in the x & y plane. But for some reason i can't get it to work.

So i need help with this. Any ideas.

I want to lay out these curves first and then i plan on offsetting them, closing them and then adding the notching. I think this way is better because it will enable me to chop up any free form surface and make a rib type construction with the laser cutter.

So your help would be most appreciated. Attached is a model file and also the start of the definition.


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Ok so my attempt at getting the curves along the x and y plane attached.

Any ideas how to get this to work.
If you're interested the grillage fab definition I made would, I believe, still work for you.

The was done making a closed polysurface from your master surface.

Here is a guide if you wanted to work with my definition and keep your master surface interactive.

Hey Taz

Thanks for that.

Good idea. Just one question, how did you make a closed ploysurface from the master surface.

_Offset surface from master surface
_Duplicate border of master surface and offset surface
_Loft the border curves
_Join the surfaces

You could set up a routine to do this in GH too...

I think your grillage fabricator would work better if you set such a thing up. Or at least a version of your grillage fabricator that can do this…because sometimes when i use your fabricator if it is just a free flow surface with no depth / thickness the rib components are not quite what you want.

What you think?
I agree with you, but I was attempting to make the definition as generic as possible.

This issue is this:

If you want to create a rib/waffle/grillage from a polysurface with a constant offset, Rhino/GH will only offset each individual surface and these surfaces may or may not intersect. Rhino/GH doesn't do "Shelling".

This becomes problematic (for me anyway...) when taking sections (curves for cutting) and determining notch locations (from intersecting planar surfaces created from the section curves) .

Extruding is much nicer/easier since it will automatically work with polysurfaces and produce a closed BRep.

So for the general case (if a constant offset is required) its easier if the user manually offsets all surfaces, cleans up the geometry, and then slices-and-dices a closed BRep.

I could set up an offset option for the special case of a single surface, but that could still produce problematic conditions that would have to be solved on a case by case basis.

I'm not sure if that makes sense, but the summary is this: Since Rhino/GH doesn't do shelling it would be a lot of work to put together a definition that would always work for any polysurface.

"So for the general case (if a constant offset is required) its easier if the user manually offsets all surfaces, cleans up the geometry, and then slices-and-dices a closed BRep."

Ok so this seems the way to go then.

Thanks for your help Taz

Sorry but again i'm having troubles with your rib builder using the following surface which is just a loft of 4 curves.

Any ideas?
Hey Taz

A quick question with the rib builder. Is the notch width slider in Inches or what?


The units should all be relative to your Rhino units...

I think the default notch thickness I have is either a 1/16th or 1/8th of an inch (0.0626 or 0.125) with a rib spacings of 1 or 3 inches.

If you're using metric units the default settings wouldn't make much sense.






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