Hi
Im a blender noob. I have been reading this tutorial http://www.shapeways.com/tutorials/creating-hollow-objects
It says there when trying to make the cube hollow, you create a smaller replica of the cube and place it inside the original one.
I just want to know — when it says ‘place it inside the original’, how axaclty do that?
Regards
Just move the smaller cube so its inside the volume of the larger object. Alternatively you could also use a solidify modifier.
If I use the solidify modifier, do I need to create an opening on the object because the tutorial says "
If you want your object to be truly hollow (i.e.: containing air, not plastic), you’ll need to add a few holes in the object wall."
Your mesh object is made out of vertices, edges and faces (polygons) which all have 0 thickness. Can’t 3D print those.
What you do is model all the object surfaces with them and that way one can tell what parts are solid and what parts are not. A cube in the example is one solid object - it only has the outside surfaces. When you put a duplicate inside, you describe an inside surface, creating a hollow object.
Solidify modifier creates thickness. It makes the inside (or outside) surface for you, based on the surface you already have and the parameters you put in.
In 3D printing the reality is that you can’t print in mid air, you need support material to make the top part. And the only way that support material comes out afterwards, is that you model some holes in, or drill in it afterwards.
When you create a model that is hollow, this process creates a wall thickness. You want the result to be 1 complete surface,well defined surface(normals pointing in the correct direction)
This is a good example.Add a cube, subdivide it several times.Delete a face.Then in edit mode select all, extrude,ESC(right click) scale inward.Then select all,Ctrl N,that recalculates normals.
If your normals are all pointed outward to begin with, the solidify mod recalculates them for you. Layer 1 in the file has the scaled cube,layer 2 uses solidify mod. In both files, click display Face normals in the N panel to see what properly oriented normals should look likeholllow.blend (594 KB)
What “top part” are you reffering to? I am also confused by your explaination why you need a hole — support material comes out?
Some 3D printers use a second material that can be easily disolved in a certain liquid, it’s used to help with printing open spaces or pieces that are supposed to be completely seperated from others.
This second material is used as a little scafold or placeholder so that parts can be kept seperated at times. In the end, when your print is done. It’s washed in a solvent and the secondary material simply disolves and your seperate parts of your prints are free and disconnected from eachother. Ofcourse you’ll need a hole or 2 to make sure your solvent actually get’s to the places it needs to be.
I can’t remember which video explained this, but if you want to get an expert explanation on the matter, try youtubing for 3D printing a working wrench or something similar.
Also sorry to ask an off topic question, but about that support material:
In 3D printing the reality is that you can’t print in mid air, you need support material to make the top part. And the only way that support material comes out afterwards, is that you model some holes in, or drill in it afterwards.
Can’t you also just leave it there in some cases?
At any rate, solidify is probably your best bet, it’s easy to use and it’s also pretty decent.
All you need to do is make sure that your solidify modifier is set up properly.
You’ll want to set it up to go inward (offset -1 usually) and maybe even use “even thickness”
That makes sense. It seems like you’ll need a hole (even if you used the solidify modifier).
Just move the smaller cube so its inside the volume of the larger object
The space between the larger object and the smaller cube will be printed as a solid right?
Yes the void between the inner and outer surface when 3D printed is where the actual material will be. Big manifold Cube has a surface area whose face normals define its’ volume. Same for the smaller cube. If you join both objects into 1, the total volume will be the small cubes + the larger cubes, if all the normals are facing outward on both cubes before joining.
Now if you flip the smaller cubes face normals to where they point inward, then join both cubes, the total volume is now the smaller cubes volume subtracted from the larger cubes. The inner cubes interior is now empty space,while its surface face normals and the outer cubes surface normals are defining the Material Volume of the printed object. The materials surface normals need to point away from the material to define a volume.
The measurement panel addon handy for determining volume, even if you mesh is non manifold, or has ngons, which is bad also.