Subtracting one part from another of an imported file

[Anonymous]

Hi,

I am very new to 3D and just now learning Fusion360. Prior I used Microsoft's native 3D Builder.

I liked it as it has a simple learning and functions more like MS Paint.

My problem is I created an object in Fusion but was not able to figure out how to do a few tasks and I fell back on my old habit

by exporting to an .obj file for use in 3D Builder.

Now I'm hitting a wall from 3D Builder, it won't let me subtract a part from another so I can create a void the way I want.

When I convert the .obj to .iges using Freecad, Fusion360 imports the file but instead of looking like it originally did in Fusion360

ie; solid objects without mesh lines which is how it also opened in 3D Builder, it loads into Fusion360 as a countless lines and triangles.

This makes my goal of subtracting the one part beyond me.

3D Builder won't do it, it tries for a few minutes but ultimately just deletes both objects.

Would anyone have some suggestions?

[jeff_strater]

Can you post your designs here?  It's a bit hard to tell without more information.  However, the fact that you mention .obj files is a red flag.  There are multiple basic types of bodies in the 3D modeling world, primarily BRep (for Boundary Representation), which is a mathematically precise representation of the model (i.e. planes are planes, cylinders are cylinders).  The second main type  is a mesh representation, where the body is represented with a set of triangles or quad faces.  This is a much less exact representation, and some kinds of operations are not valid on mesh bodies.

I am not familiar with 3D Builder, but my guess is that it produces mesh bodies, which are not going to work well with the native BRep bodies in Fusion.  If you want to stick with mesh modeling, I would recommend Meshmixer (http://www.meshmixer.com/) which is really tailored to mesh modeling.

Anyway, post your model here if you want more information than that.

[Anonymous]

Jeff,

Thank you for replying.

I am ok posting the file.

Because I took the bulk of the file from Fusion to 3D Builder, the file formats I have are >stl, .obj, .3mf and .ply

So I am attaching the obj file.

The part protruding past one end is what I'm trying to subtract, so it results in a thin sleeve/cavity for paper with

messages that can easily be changed.

[jeff_strater]

@Anonymous,

Yes, this is a mesh body.  There is just one body here, it's not completely clear to me what part you want to subtract from what other part.  Because this is a mesh, it's not going to work very well with Fusion.  Smaller mesh bodies can be converted into a BRep, so some limited workflows can be used, but this mesh has too many faces to convert.  You might be better off re-creating this model in Fusion as a solid body, or using a mesh editor like Meshmixer instead.

Sorry not to have a better answer.

[Anonymous]

I am attaching an image. It should be two separate pieces.

One is the main body and another is a thin curved piece inserted into the main body.

IF I can "subtract" the thin curved piece, I'd have the sleeve I am after.

Creating that sleeve is what was proving to be the hard part for me in Fusion, that and the 8 slits that are also the result of a subtraction leaving a

desired void which is now a window, once printed.

I'm trying in Meshmixer now. The blue is to be removed from the red.

[laughingcreek]

I think it would be worth your time to learn how to model this shape entirely in fusion.  trying to hop between brep models and mesh models will likely cause you a lot of frustration, and be a harder process over all.  I think you would get plenty of help here make this from scratch in fusion, and the end result will be much more manageable.

[jeff_strater]

This is a very strange mesh body.  It looks like it should be two bodies, but yet there is only one body.  This is true in both Fusion and Meshmixer.  You can see that when I select a few faces from the part of the mesh that you had highlighted as blue in your image:

I did not try any other mesh editors.  I don't know if this is a peculiarity of exporting an obj file from 3D Builder.  In that application, are these two bodies, or 1?

[laughingcreek]

There are just multiple shells grouped together.  fusion saves out multiple bodies to a single mesh body like this also.  The weird thing is in fusion fails to separate the shells, but mesh mixer separated them just fine.

[Anonymous]

I'm trying something simpler, completely in Fusion360.

I created two squares.  One is 45mm squared. the other is 48mm squared. When placed next to one another, the larger square doesn't align naturally.

How can I pinch the larger square's 4 corners that need to match the smaller square so they match without altering the other 4 corners of the larger square.

I envision a simple left click of the mouse, hold the button, drag the point to its new location and let go of the mouse button but I'm 100% certain is is not that easy.

(I tried).

I also tried the press/pull and scale options, neither worked as they act upon the square as a whole.

Ideally I can do each corner individually if not, then one edge with two corners.

Is this even possible?

[Anonymous]

It should be two, at least in 3D Builder it is. I was able at one point to have Meshmixer see it as two but haven't been able to duplicate that.

[jeff_strater]

@laughingcreek:  how did you separate the shells in Meshmixer?  I'm not a Meshmixer expert by any means.  But, when I bring that obj file in, this is what I get:

I only see one body.  How do you separate them?  Thanks!

[Anonymous]

It only worked once for me and it did execute the request using the shift key and left clicking the main body first, then the sleeve.

Then boolean difference to subtract the second from the first.

It worked only to see Meshmixer crash.

I've given up on doing this and will try creating it from scratch using Fusion360.

Do you have any insight to my squares I asked about?

[jeff_strater]

Thanks, @laughingcreek, learned something new in Meshmixer today!

[jeff_strater]

@Anonymous, regarding your "squares" example.  Yes, it is possible to create the shape you are looking for, but it is a very different mindset than what you describe here.  In Fusion, you would not start with two differently-sized blocks, and expect to perform the edit you describe to get them to line up.  You can do some of that type of editing with the Draft Faces command, but to be honest, I would create the blocks to be the correct size from the start.  For instance, here is one way to achieve that goal:

[Anonymous]

I was hoping for a solution that didn't render the object I have now useless. I simplified the description becuae it is essentially two boxes but there are some areas removed that I'd have to repeat.

Oh well.

More time to learn.