making negative for mold

[joegalicic]

Hey everyone i'm working on puting together a negative of a mold to cut out. the problem is the object is a mesh and when i draw my box around it and go to boolean it will not work for some reason, even when a go to mesh boolean, the object is a flower pot, hopefully you'll have some ideas im kinda at a lose

[awerby]

Did you build this mesh in Rhino, or import it from someplace else? Rhino isn't great at Booleans, and working with meshes doesn't usually go as well as working with Rhino's normal NURBS surfaces. So if you built this from scratch, back up past where you created the mesh and try splitting the surface with a plane at the parting line. This should give you a negative on one side, and positive on the other.

If this is a mesh you imported (for some reason) then try Rhino's Drape function to get a surface you can deal with. If it's a symmetrical part, you should only have to drape one side, down to the parting line.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[chmillman]

You probably want to try this in the Rhino v5 Beta. You can only use the MeshBoolean... operations on meshes. If they fail, you can also try MeshIntersect and then try to split the mesh with the intersection found (if it looks correct).

If the object is not horrendously dense, you could try MeshtoNurb and then try your Boolean afterwards - but beware, if you computer does not have enough memory, this WILL crash it. Read more about MeshToNurb here:
rhino:meshtonurb · McNeel Wiki

If it succeeds, convert the object back to a mesh afterwards with Mesh command (leaving it as surfaces will be far too memory consuming).

Otherwise, it's time to get into re-modeling the flowerpot in Rhino's native NURBS surfaces. --ch

[joegalicic]

Hey guys thanks for all the info, the drape feature would work great if it was a ble to hold more detail, it gets very distorted is there a way to fix this, also the mesh is not one that i drew and im not sure what it was drawen in.

[BurrMan]

Did you try these commands?

CutPlane
MeshSplit
DeleteMeshFaces

[flux_001]

Hello-

I would use the command MeshToNurbs and you can use the solid/polysurface boolean commands easily and trim etc and convert back to meshes if you like.