Why does Tinkercad seem to be better with STL's than Fusion?

[Anonymous]

When editing a .stl in Fusion its a complicated affair of mesh and trying to edit is quite complicated. Even after making the body a solid its is not the same as Tinkercad its still hard to edit parts like position for cuts and filling parts of the model. The pic kinda shows what I mean.

On Tinkercad you click import and the model seems to be converted more into a 'proper solid' and ready to edit and do anything with. 

Does Tinkercad have a special way it imports stl's? Is there a way that I can set Fusion 360 up so it mimics the way Tinkercad imports and edits .stl's 

[TheCADWhisperer]

Stl is faceted planar triangles - generally of little use for engineering design other than as output for 3D printing.

The sooner you come to the decision to abandon planar faceted triangles as a way to do engineering design - the sooner your design life gets easier (unless you are an artist, in which case - carry on).

[TrippyLighting]

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@Anonymous wrote:

... and the model is a proper solid and ready to edit and do anything with...

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Define "proper solid" in technical terms, please.

[Anonymous]

Sorry don't have a technical term lol. I was just try to explain it seems to convert it somehow into a better more usable solid than fusion does.

I'm really just looking to see how Tinkercad actually imports .stl compared to Fusion as it obviously does something completely different to make it fully usable from import, vs the conversion process that you have to go through on Fusion and it still behaves differently. 

For example the issue is I need to edit .stl for people who are 3d printing, so for example say they need a hole added to their item. In Fusion I need to import as mesh got through whole process of making it into brep/solid etc then have to try and get the hole where they wanted it. In Tinkercad I import, cut the hole, export. There is around a 75% saving in time for simple tasks like that.

Is there any of the team that worked on Tinkercad available to comment on the way it imports/converts .stl vs Fusion

[TheCADWhisperer]

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@Anonymous wrote:

... comment on the way it imports/converts .stl vs Fusion

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The underlying geometry in Stl is still planar triangular facets (doesn't matter what visualization smoothing techniques the software uses - it will never be smooth in reality).

What product do you know of (other than cut diamonds) that is all planar facets (no curves)?

[TrippyLighting]

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@Anonymous wrote:

Sorry don't have a technical term lol. I was just try to explain it seems to convert it somehow into a better more usable solid than fusion does.

I'm really just looking to see how Tinkercad actually imports .stl compared to Fusion as it obviously does something completely different to make it fully usable from import, vs the conversion process that you have to go through on Fusion and it still behaves differently. 

Is there any of the team that worked on Tinkercad available to comment on the way it imports/converts .stl vs Fusion

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As @TheCADWhisperer has already mentioned, .stl files contain triangulated meshes. No import routine is going to change that!

That mesh cannot be converted into a "proper" solid. A proper solid in the real CAD world is a non-faceted object consisting of analytic geometry and NURBS, stitched together to form a BRep. 

A BRep is a mathematically precise description of geometry without a finite resolution and with topology in a mathematical sense. When that BRep is exported into a .stl, so into a triangulated mesh essential information is lost. Triangulated meshes have a finite resolution and no topology!

That can not be 100% re-created and definitely not with automated conversions.

What TinkerCAD is very likely doing is that it uses mesh operations on the .stl

Fusion 360 converts, on the other hand, convert every triangulated facet into a trimmed NURBS surface, so all subsequent modeling opreations can be performed using the algorithms provided by the geometric modeling kernel.

[Anonymous]

Thanks for the insight.

When 99.9% of the people wanting their files tweaked for 3d printing by us only have the .stl we need a method to be able to change them quickly.

I just find it weird that Tinkercad can perform these operations easily compared to a great program like Fusion. Like I said earlier we had a file that needed a hole placed in it and a part filled in. It was literally a 2 min job in Tinkercad import, cut hole, export. 

We tried to do the same thing in Fusion and it resulted in conversion, at one point having to reduce faces and many other things and the end result was the hole was not correct, even after letting one of our best engineers who has over 20years experience have a go. 

It may not be the import process then but it is obviously doing something very different because of the way it can edit and manipulate the model compared to fusion. With Fusion being the more advanced program we were wondering if there was a way to mimic Tinkercad (which is another Autodesk product and says the upgrade route after this is Fusion 360) the way it handles the files

[TheCADWhisperer]

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@Anonymous wrote:

When 99.9% of the people wanting their files tweaked for 3d printing...

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Let's say that rather than 3D printing - you were going to use conventional machining to manufacture the part in the image in your original post.

Would you create the "cylinder" and "helical thread" features by milling thousands upon tens of thousands of very tiny planar facets to sort of represent smooth curves, or rather than milling, would you mount on a lathe and turn the cylinder and chase the thread? 

Fusion is intended as an engineering tool rather than as an stl editor.

When it comes to real world production we usually use conventional machining processes rather than 3D printing (I would guess 99.9%, but that is just a wild guess that I wouldn't even bother to research).

[TrippyLighting]

It seems to me that TinkerCAD is an online-only program.

I had intended to look into this a little further but have no interest in signing up for anything else.

[TheCADWhisperer]

As I contemplated this a bit more I thought, "What program was used to create that "helical" thread? TinkerCAD?"

I would be surprised to find out that TinkerCAD could create that geometry.

My speculation is that the geometry was actually created in a true solid modeler - in which case native or neutral format like STEP should be available rather than mere stl triangular planar facets.

[Anonymous]

I never said that the original model was created in Tinkercad, merely that is what it looks like to manipulate vs Fusion. Various programmes are obviously used to create the parts. But almost all the files that are brought to us for production by customers are in .stl format either because the original files are missing and they only have the .stl print files or because they have purchased/downloaded them through various 3d printing websites.

The issue comes that those files need tweaked and we have found the quickest way to do that is by using Autodesk's own Tinkercad platform. But Tinkercad is a very crude platform to perform most tasks, but what it does better than almost anything we have found is its ease at importing and easily manipulating any .stl without any issue. Having this ability with the tools available in fusion would be ideal. We were told Fusion 360 was the upgrade route from Tinkercad, but as such its cannot handle the .stl with no effort like it does, there is around 75% extra work being able to try and manipulate them. 

Posting here was incase any of the software developers used this forum and were able to provide any insight as to how the software differs in handling the file and if there were any option to change in Fusion that could mimic this operation. But alas I don't think many of the software developers frequent this area. We obviously have the incorrect software and will have to find another software.

[TheCADWhisperer]

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@Anonymous wrote:

But almost all the files that are brought to us for production by customers are in .stl format either because the original files are missing and they only have the .stl print files or because they have purchased/downloaded them through various 3d printing websites.

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The moment a file is converted to stl - the quality of the geometry is reduced to such a low level that I would not attach my reputation to the geometry (for most uses).

I would request native non-stl geometry from the customer

or

remodel from scratch using the stl only for reference and edit as needed (and then return a stl to them if that is what they really need).

Personally, I would not attach my reputation to an edited stl (for most uses).

So to meet my quality standards - it is going to cost the customer a bit more money if all I have to start with is an stl.

Stick around - eventually an Autodesk rep will chime in here.
We are just users like you.

Edit: Let my be a little more direct with my opinion.  Stl is rubbish (for most anything other than 3D printing.)

[laughingcreek]

Just to answer the question of "why" directly-

it's already been pointed out that mesh models and brep/nurbs model are VERY different types of models mathematically.    So they use different types of tools to manipulate them.  Tinker cad was built from the beginning to work with mesh type objects, and fusion was built from the beginning to work with brep/nurbs type.

Although fusion has added some mesh capabilities, it's never been it's focus (and frankly sucks at all things mesh).  It's core target audience are primarily  engineer types, who are more interested in the brep/nurbs models.

So "better" is relative to what you need the tool for.  

[LeonardoBN]

I do not have new to add to the discussion, but walked through a STL path like that in the past.

I can't remember well, but I think I've never used Tinkercad. When I started working with 3D printing I went directly to Meshmixer. Before I learnt how to use Fusion, all my designs came from already existing STL files, so I relied to MM in that time for everything. I still think its default visualization a bit strange (like the Fusion's one), but nothing that a wireframe and a matte finish don't solve.

After I started modeling my own parts, I though I could use Fusion to edit STL files like I did with MM, but it doesn't work well and I kept MM for those tasks.

[Phil.E · Accepted solution]

Just to be clear about the core of your question:

• Tinkercad - built to be a mesh creation and modeling program from the ground up. 100% mesh.
• Fusion 360 - built to be a "fusion" of Brep solid and surface body modeling, T-Splines surface modeling, mesh editing, CAM machining, PCB designing, rendering, simulation, generative design, and drawings package. In other words, not a "mesh modeling" application like Tinkercad.

There is a workflow to tie Fusion and Tinkercad together. This class explains some of that.

https://academy.autodesk.com/course/134629/tinkercad-fusion-360

Typically the workflow for 3D printing either is 100% mesh driven, or starts in a Brep model that is exported for printing. Fusion is built to do the latter.

Also, regarding the image you show. Those models have identical geometry. What you see in the Fusion image is the result of a preference setting. Try setting your mesh display to Flat in Preferences.

Thanks,

[jeff.meddemmen]

Hi, 

@Anonymous I totally understand your question here as have thought the same myself. I.e. for my basic hobbyist application of designing and building 3D printers I often want to assemble all the component parts in CAD first before purchasing. Dealing with a mix of STLs and STEP parts is really really painful. You may be mixing different designs together and only STLs are available from the author and want to tweak them for your printer design. 

Coming from Tinkercad to Fusion I was really surprised how much more difficult this is, even just arranging, aligning etc is really laborious. Yes I could work on each model to convert them to solid objects or even redesign from scratch based on the STL but we could be talking about 40+ parts. Tinkercad you just import them all in and you can immediately manipulate, arrange and make alterations to them painlessly. To call out one specific case, holes. If you import an STL mesh with a hole in Fusion its really a labour to delete all the faces and loft etc 

Thanks to some of the other posters for going into the technicalities of it, but from a user perspective the answer is just yes, as surprising as it sounds TinkerCAD is far more powerful than Fusion for assembling 30+ STLs without any need for conversion. 

I assume Inventor would have been similarly designed to Fusion as to its handling of meshes? Also Mesh Mixer I assume would not be an appropriate tool for assembling large numbers of mesh components?

Cheers

J

[Phil.E]

Thanks for the fresh look on this old post.

I agree, Tinkercad, a mesh modeling application, is much better than Fusion at mesh modeling.

Your assumptions about Inventor are probably correct. I haven't worked with meshes in Inventor before, but it seems reasonable that another solid modeling design application would have similar limitations with mesh.

I don't know what Mesh mixer is capable of, sorry cannot comment.