Very large OBJ - export to format for Fusion 360

[Andrew Wright]

Can anybody help with a problem please?

 

I have a computer with the following Autodesk software packages installed…

3DS Max 2024

Fusion 360 latest release

Inventor 2024

AutoCAD 2024 full 3D version

Netfabb Premium 2024

Meshmixer latest version.

 

I purchased a 3D Model file for a Caterpillar 395 Tracked Excavator which is approx 75Mb with approx 2,500,000 facets/polygon/triangles in OBJ format. The file is made up of 15 parts within the OBJ file, but the parts aren’t divided into the parts you would split them up into. My guess is the model when created and saved to OBJ assigned them not optimally. ie the cab and body of the machine also has pipes running to the boom within, when you’d expect them to be part of the boom part.

 

This file is scaled correctly and accurate to the manufactured model.

 

I would like to load this file into Fusion 360 as solid bodies, but it is too big and too many faces etc.

Therefore if I could get the model in Fusion 360 in a mesh format I could reference off in sketches and features, I can rebuild from scratch using them to work from and create new bodies for the entire model.

 

I have tried the following methods….

 

1. I have used 3DS Max to export the OBJ file into DWG & DXF which load into fusion 360 but can’t be referenced from to recreate the model from scratch.

2. I have tried to use 3DS Max to export it as a STEP file but it is too complicated and fails. I even tried to just export one part of the OBJ as STEP but can’t get Fusion to make the STEP Solid due to face errors.

3. I have used FreeCad to try to export them to STEP with no success.

4. I have used Meshmixer and Netfabb to try and make a simple Arm Piston (Which is one of the separate objects in the OBJ file) manifold so it can be brought into Fusion as a Mesh and then made solid, but even the simple part has too many faces/triangles etc so fails. I’ve tried multiple methods of using Fusion Mesh tools to Rebuild/Reduce/Face Groups/Convert/Repair mesh functions in every order and combination with no success. 

 

I am very good with Fusion and Inventor, I’m ok with AutoCad, Meshmixer and Netfabb, and to be honest out of my depth with 3DS Max and FreeCad.

 

I have had some ideas but can’t execute them as I’m not familiar with 3DS Max.

 

A. I could display the model in 3DS Max in Orthographic mode in all 6 orientation and if I could save a DXF of what is shown on the screen viewport without hidden items, I would have 6 head on views in DXF I could load into fusion 360 and reference off those to recreate the parts as if they were 2D vector representations of what you can see in each viewport.

 

B. Save each viewport as a print screen as a pdf and insert those in Fusion as canvas to draw from.

 

But I have this model that is precise and would prefer to find a way to reference directly from it somehow.

[James Vella]

Andrew, what is the end goal here? Do you need it for 3D printing? Otherwise why not just use the model as it is if its just for rendering purposes? 

I would say you are right about the obj export, do you have the native 3dsmax files? Are they different in any way?

I could go into more details but for now if you can clarify these things we can discuss some more options since it all depends on the intent.

[Andrew Wright]

James

Thank you very much for your message.

I want to use it in Fusion 360, although it accepts OBJ meshes, until they have been repaired and triangles reduced significantly, Fusion 360 would allow you to generate a solid from the mesh, which is the ultimate goal.

Fusion wont allow you to create a sketch and reference of the mesh either, until its a solid.

You can create a sketch through a mesh but the sketch needs to be traced over with arcs and lines.

So i know i can export to DXF in 3DS Max and open in Autocad and use the FLATSHOT function to create a 2D representation of the mesh in the view that it is in.

But this is a real long winded process.

In 3DS Max you can have different views i believe of the OBJ.

So i thought if i could create a 2D DXF of the OBJ in 3DS Max with hidden edges etc hidden, its almost like printing to a PDF, not sure if that is even a function but you get the idea.

If i could save a view of the OBJ as a 2D DXF, i could bring that into Fusion and directly model and reference from those to build and recreate the OBJ as a solid which is the ultimate goal.

I have asked the 3D Model seller if it could be converted to STEP which would be another solution, but he seems hesitant.

I dont use 3DX Max and to be honest looks very daunting a bit like Blender & Maya.

I normally work in Inventor or Fusion.

The OBJ i received is 135Mb and the object split within it isnt ideal or logical, which i could work around.

But with such a big file i cant get it to save as Step, as there are unmanifold items within it.

Again i have asked the model seller to make it manifold and logically split the parts, but i havent heard from him for a few days, so he maybe reluctant.

So thats why i wondered if a 2D reprentation of the view in 3DX Max could be saved ideally in DXF or SVG or something similar.

Ive tried to repair the OBJ with Meshmixer and Netfabb, but it makes a huge mess.

When i tried to export the OBJ as one mesh it produces a error of "its a rats nest".

Hence asking advice in this forum as ive exhausted what i can natively do with the packages i am familiar with.

If this isnt possible then i will have to take the plunge and try and learn 3DX Max, but currently i have promised a Fusion 360 design based on having the model already drawn and converting it, without thinking too much about it, and foolishly i now realise that without the orignal OBJ being split logically and manifold, my repair tools and workflow is running into probelms.

Sorry for the long winded reply, do you have any suggestions?

And Many thanks for taking your time to reply, greatly appreciated.

 

 

[James Vella]

My question is why do you need it as a solid mesh in Fusion? I understand that's your native software. I understand the hurdles you are facing. But what I don't understand is the end result, Are you just trying to show your client the model in different perspectives, or are you trying to show the client orthographic views (front/side/top) like a CAD drawing? Please be specific of the end goal, what your client is actually expecting, something they can 3D print and hold, 2D drawings... what is the end goal?

The DXF export in 3dsmax is not really designed for this, its basically for clean ArchiCAD (sp)lines. Its not really what you are looking for in terms of taking a 3D object and turning it into a 2D representation. While you certainly can render orthographic views in 3dsmax using different techniques (like toon shader or similar) I'm not sure if that's actually what you need. 

If you need to clean up in 3dsmax use the boolean or proboolean Modifier tool(s). This will take any intersections through the center of the mesh and remove it. Essentially once you have combined all parts using boolean you should end up with a 'solid mesh' basically. It will reduce all the geometry you don't see and keep what is external... if that's what you require. I'm just punting here since most of what have mentioned don't really pin point anything in particular. Can you just show some images of what your final intention is; for example this is something I have done before for a client, this is what they want A -> B -> C. This will make it far easier for people here to suggest something that might suit your outcome. The question you have is far too vague since 1) There is hundreds of ways to do things in 3dsmax 2) half of them might be a waste of your time if you are not very specific.

Edited November 29, 2023 by James Vella

[Andrew Wright]

James

Thank you for your reply.

Yes i havent really discussed the final outcome reason, sorry.

The idea is to build a parametric solid model from the OBJ.

The end goal is to create a 1/14 scale RC Model of the Excavator from the solid bodies.

The model will then be sliced up into 3D Printable parts.

The model will need to be adapted to introduce, bearings, motors, hydraulics, Pumps, lights, controller etc.

Starting with a solid model allows the component parts to be tested in simulations, as due to the layer lines and stress during its operation i will need to introduce steel plates, carbon rods, hinges, pins, gears etc to achieve the rigidity required at the end.

So the initial idea was to have the model in step format which would allow for the above alterations.

My previous message was just me trying to solve a problem the easiest way to rebuild it into a solid model.

As the model is so very detailed as per the available literature, the whole idea was to change the OBJ into STEP, so i dont have to redraw it from scratch, but with references from the DXF file.

I think reading between the lines i am probably going to have to learn 3DS Max to make these alterations necessary to import the separated OBJ's of the parts of the excavator, that can be converted to a solid in Fusioin.

Without being able to reference from the OBJ model will now mean i will have to obtain all the reference drawings and data from multiple sources and determine the dimensions manually for the whole model which im sure you are aware for something that complicated will take a huge amount of time.

This is a learning experience for me with OBJ Meshes not split logically and being manifold, generally i get them and that is already been done.

When researching this model i had noticed that some where avaialble in STEP on one website but not on another from the same creator.

Foolishly i assumed that it must be fairly straight forward to export to STEP.

Any suggestions you may have i would greatly appreciate.

Many thanks in advance and for your time to follow up this enquiry.

 

[James Vella]

I would say if the original model was not designed for 3D printing then yeah, its going to be an absolute mess for that kind of workflow. So you are probably right and need to rebuild it. However I would be inclined to just trace over it if you are happy with the current shape. I would just break it up into the logical parts, bring those parts into Fusion then trace the shape and discard the original after. Rince, repeat. Considering you have to build all that extra stuff for the RC Rig then its probably worth doing it that way anyway since you will need space for motors, bearings etc. 

What is the original file format? Do you have anything other than OBJ, for example did the original model come as 3dsmax? If so does it have subdivision levels? If that's the case you should be able to switch the subdivision off giving you a low poly mesh to work with so it should be more optimized to export to Fusion. 

[Andrew Wright]

James

Thank you again.

If I had the original 3DX max file would that have any form of history in it?
I presume the model would of been built with primitive shapes extruded along paths, or would it of been surface modelling.

i can see a wireframe view that seems fairly consistent with the shapes they form.

Could you give me some pointers or features/functions in 3DS max to use to achieve the following assumed workflow.

1. Change view to wireframe.

2. Select editing mode.

3. Highlight geometry to merge.

4. Merge into a separate body/object in the scene.

5. Reduce subdivisions.

6. Make manifold.

if I know which functions to look up to achieve this, it will save me learning the whole of 3DS max.

many thanks in advance

[James Vella]

There is no form of history like Fusion has. Modelling in 3dsmax is mostly freeform, so no mathematical stuff, its 'good practise' to collapse everything when selling 3D content so everything is basically a mesh at this point, you lose all extrusions, lofts, sweeps etc for most situations. 

1. Toggle F3 for wireframe/solid view. Or in the top left corner of the viewport You have something like [Orthographic][Standard][Default Shading] - select default shading and you can select different view types.

2. To select editing mode your object must be an Editable Polygon/Mesh. You will see this in the Modifier tab on the right side of the screen. Buttons 1,2,3,4,5 Are Vertex, Edge, Border, Polygon, Element mode. If you have trouble a quick way to make something Editable, you can right click on the object > Convert to > Editable Polygon. 

Edit: Element mode might be your best option since its a useful way in 3dsmax to grab large chunks of objects that are meant to be one piece, so you can select an Element like a wheel and then 'detach' it. Hold control when selecting multiple elements, so for example the wheel may not be the same element as the rubber on the tyre, but you can grab both together holding control and clicking. This way you can take that wheel and import it into Fusion and trace over it. Rinse repeat for the other elements and each object should be small enough to export/import without much issues.

3. Highlight geometry to merge > What does this mean? This is an entirely different concept in 3dsmax and I'm not familiar enough with Fusion. Edit: I think from a quick youtube this means boolean modifier in 3dsmax, try it see if thats the one you are looking for, same with your next question.

4. Merge into a separate body/object in the scene > What does this mean? Do you mean copy/paste between different scenes? You can File > Save Selected or use a copy/paste script if that is what you mean.

5. You can use Pro-Optimize in the modifier tab to reduce subdivisions. There is also Retopology modifier. There is a few others but they are probably the most fastest ways of reducing geometry count with less artifacts.

6. Good luck with manifold. If the geometry has holes and was not designed like this its going to take a long time, I would do that in Fusion by tracing over it. You can try cap holes in Edititable Polygon mode but generally its more miss than hit.

Dont worry about learning 3dsmax, ive been using it every day for the past 15 years, Ive barely scratched the surface lol. Theres many many ways to do things in 3dsmax, all have a combining effect so you will truly never learn everything, but theres plenty of ways not to do things thats for sure.

Edited November 30, 2023 by James Vella