3c. Ribs – Rib Grasshopper

Ribs Definition

Model: Rhino Ver. 4 SR8

Input: .3dm, .ghx

Note: .3dm file and .ghx need not be always together. You can use a .ghx file on any .3dm file in Rhino.

1. Set a BRep in Rhino and create a new BRep Icon in GH. Set One BRep and choose the BRep in the Rhino.

2. Attach a BBox to the BRep. This creates a box surrounding the BRep.

3. Using the Explode Icon, you can separate the elements of the BBox into edges, faces and points.

4. Attaching the slider to the Explode Icon will allow you to choose the element that you want to refer to.

5. Attaching a PFrames Icon, will create planes that are perpendicular to the edge that you chose. As usual, attaching the slider to the PFrames icon will allow you to choose the number of planes that you want.

6.  Attach the intersect plane/BRep icon to the PRframse and BRep to create curves along the BRep. This will be the position of the ribs.

7. Using the move icon, you are able to move the existing curve along the BRep to the direction and magnitude that you want. In this case, it is in the -Z direction. 10mm.

8. After offsetting, extract the end points of bot top and bottom curves. Using the End icon.

9. Attaching the Line Icon will create a line from the end points you have extracted.

10. Duplicate the definition. This is supposed to be the other  direction ribs.

11. Change the identified slider which is attached to the List icon in the duplicate set to find the edge perpendicular to the first edge.

12. Using the Intersect plane with curve icon, you can create points on the curve. Using the plane from the other set of icons and the curve from the first set, this will be the position of the notches.

13. Using the Rectangle icon, create rectangle that is in the correct plane and you can set the thickness of the ribs and the depth of the notches.

14. You can combine the rectangle and the ribs using the Region Difference icon. However, before the geometries reach the Region Difference icon, it has to go through a Path Mapper so that GH knows which curves to do a Boolean. In this case, the option in the Path Mapper is {A;B;C;D;E;F} and selecting {E}.

15. Do the same for the other set of icons. This time changing the side of the notches and the plane of the notches. Highlighted in the image below.

16. Final result of GH Ribs Definition.

17. Result of offsetting instead of moving the curve to form the ribs. Because by using the move command, you can only create ribs of BReps that have not too steep gradient, as too steep a gradient will cause the depth of the rib to be very shallow thus losing its strength. This would create ribs that have a uniform depth regardless of the gradient. However, the notches will have problems thus I do not recommend this yet.

18. Finally, using Rhino or panelling tools, you can move and flatten the ribs onto a plane and use the laser printer to cut out.


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