Create an invert for a mould - Printable Version

Create an invert for a mould - Printable Version

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Create an invert for a mould - GRUMP - 11-22-2021

I have this shape and am trying to set it into the cube then delete it leaving the shape inset as an invert in order to create a mould. Could anyone help me with the procedure?
I have put 5 cuts in the cube and tried using the Boolian Test function with no success.
Inset, dissolve, collapse have also not helped.
https://drive.google.com/file/d/1fdGpqLTLNMXNbS6ccL2CdODY1giiXXdh/view?usp=sharing
Thanks.

https://drive.google.com/file/d/1gqUOiHsVcJEIxWlTR86YWWRgJBbNXSmL/view?usp=sharing

RE: Create an invert for a mould - micheus - 11-23-2021

That will be difficult in the current state...

- First of all, boolean will not work with co-planar faces (those faces overlapping the cube face, for instance), but this is a minor problem since we could to use Select->Similar Normals to select the STL_Object's top faces and extrude them allowing us to use boolean and then remove these extra faces;

- That STL_Object is in fact a set of 25 objects grouped. We need them Separated to be able to provide the fixes;

- By hidden the big objects we see there are garbage;

- From those garbage, the triangle is a face badly arranged (the green polygon) as well as the "edges" (which are in fact narrow faces - red lines);

Here is some steps that can be used to fix them

This one requires more attention since there are two vertices overlapping each other and only one must be kept. Try to remove one and see what happen. Remove the one that requires less work from you to rebuild the faces or that creates less inconsistencies.
To see which of them you are about to select, check the information on top when you move the mouse closer them. You should see the vertex Id number. By moving the mouse around you may see the Id change.

These are some points to try guide you to fix the model before you be able to apply boolean operations as well other commands that may fail due too many mesh inconsistencies.

To fix an object with a bad mesh sometimes worst than model it entirely.
Is there a reason for you to be importing the STL file from another application instead of be creating the object with Wings3D and then export it as STL to be printed?

RE: Create an invert for a mould - GRUMP - 11-23-2021

Thanks for the help and detailed explanation, A bit more than simply making shapes then?

The model was created in Wings3D saved as STL and printed as a prototype in a single session. When the fit was confirmed I was asked to create a mould from it for future use as the recipient doesn't have a printer but wants to reproduce in silicon.

Original model
https://drive.google.com/file/d/1OfzFUPIEW_awpR1hx08JXf2FJ9g60eUc/view?usp=sharing

RE: Create an invert for a mould - micheus - 11-23-2021

Humm.
If it was made with Wings3D and not imported, you need to take care with the operations you are using since it's not usual it to create so inconsistent shapes like this.

Also, I suggest you to try tessellate it on export (if possible) and keep the original Wings3D project using quads. It helps to see the mesh clearly (it has too many polys that difficult to check it).

RE: Create an invert for a mould - GRUMP - 11-23-2021

Sorry, still very much a learner at this point. The original .obj file should have been saved tessellated as quads.
I wonder if it may have gotten worse by being cut in half by the Prusa slicer and saved as STL.

Never mind I have done the necessary by milling it in aluminium.

RE: Create an invert for a mould - micheus - 11-23-2021

Quote:The original .obj file should have been saved tessellated as quads.

This should be the right file to work with. Although, one of those issue I found is already on the top of the sphere. That part would need to be rebuilt, but it's a very simple fix.

Quote:I wonder if it may have gotten worse by being cut in half by the Prusa slicer and saved as STL.

That would explain the amount of malformed faces in the project file you first shared. Too much conversion in the process.

The best practice would be work in the main project always. If you need to cut it in half section that can be done just before to export and than undo.
When the model has the correct shape then you can make the cut permanent.

Probably the boolean operations would work better in this scenario, although it's not infallible. Mainly because of that high detailed sphere.

RE: Create an invert for a mould - GRUMP - 11-24-2021

You explain things very well, thank you.
I will take more care with my process in future.