topic Re: Tube through surfcace body in Fusion Design, Validate & Document Forum

Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 09:09:39 GMT

I am trying to add a tube for a carbon spar to a wing section. I can convert the stl into a b-rep and I end up with a surface body. Essentially i want to cut a hole through the body and add a tube but can't seem to find a way to successfully do this. I have sketched a circle where I want to delete material and then add a tube.

Any help much appreciated.

Re: Tube through surfcace body

davebYYPCU — Tue, 21 Apr 2020 09:22:27 GMT

Should work, what steps are not working for you.

Solid > Extrude > Cut the circle through the wing.

Solid > Extrude > New Body for the spar,

Solid > Modify > Shell - solid bar for a tube by selecting both end plates, setting wall thickness.

Might help....

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 09:47:32 GMT

Step 1 fails:

Error: There was a problem combining geometry together.
If attempting a Join/Cut/Intersect, try to ensure that the bodies have a clear overlap (problems can occur where faces and edges are nearly coincident).

Re: Tube through surfcace body

davebYYPCU — Tue, 21 Apr 2020 10:04:39 GMT

Then the conversion is not so successful, 8000 faces,

using STL in Fusion is limited...

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 10:05:47 GMT

What's a better tool to achieve the result?

Re: Tube through surfcace body

TheCADWhisperer — Tue, 21 Apr 2020 10:43:01 GMT

Model natively and forget the faceted stl rubbish.

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 10:59:59 GMT

wish i knew what that meant or how it helped edit this stl

Re: Tube through surfcace body

TheCADWhisperer — Tue, 21 Apr 2020 11:08:05 GMT

Have you gone to the Tutorials?

Can you Attach a couple of your prior projects leading up to this project?

Can you Attach this project?

Are you familiar with the differences between editing surface bodies and editing solid bodies.

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 11:15:02 GMT

I'm just trying to edit an stl that I have not designed. I would have thought simply putting a tube through it would have been relatively straight forward.

Re: Tube through surfcace body

TrippyLighting — Tue, 21 Apr 2020 11:53:53 GMT

@Anonymous wrote:

... I would have thought simply putting a tube through it would have been relatively straight forward.

A lot of people think that this should be straight forward, but that isn't the case.

If the basic foundation is missing then there is really no foundation for that thought!

The problem is that .stl files were never designed to function as an input to a design process that requires accuracy. .stl files contain triangulated mesh files and initially were devised as output to the first stereolithography 3D printers.

Triangulated mesh files, in particular, have a finite resolution and lack topology in a mathematical sense. CAD geometry, on the other hand, is represented in the form of BRep containing analytical geometry and NURBS surfaces.

Those are mathematically precise, resolution free descriptions of 3D geometry and include topology.

When a triangular mesh is created from that form of geometry information is lost and cannot be fully re-created.

Reverse engineering precise geometry from a triangulated mesh is not trivial and requires often expensive software and the skill to do so.

When such a mesh is reduced in polygon count to be converted to a BRep in Fusion 360 each triangular facet is converted into such a mathematically precise surface description. That is by nature much more computationally involved than a mesh. Thus the limit to 20k polygons. Problems such as near-tangency and near-coincidence then prevent boolean operations to succeed.

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 12:03:39 GMT

I have an RC plane wing design which I am trying to modify to add a stronger and longer carbon spar. Hence designing from scratch not really an option.

Project attached.

Steps so far.

1. Imported STL

2 Turned off capture design history.

3 Convert to Brep

4 Turn on design history

5 Create sketch with circle for intended tube

Steps to complete ( may not be the correct steps or terminology)

1 Create 173mm surface extrusion from sketch

2 Delete any object within the extrusion

3 Join extrusion to wing part to create tube

4 repeat on further wing sections

Any help would be most appreciated.

Re: Tube through surfcace body

TheCADWhisperer — Tue, 21 Apr 2020 13:52:59 GMT

@Anonymous wrote:
I have an RC plane wing design which I am trying to modify to add a stronger and longer carbon spar. Hence designing from scratch not really an option.

How do you arrive at that logic?

Of course it can be designed from scratch.

It would be far easier to design from scratch than to work with flawed geometry.

Turn on Shaded with Edges visual style.

What do you observe?

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 14:22:46 GMT

It's not really an option for me. I've got 8 wing sections to re-design, that may be a walk in the park for an experienced cad designer but i'm not that! I'm used to designing small parts from sketches as solids, wing design is out of my league at this point! Of course anything can be designed from scratch, if you have the required skillset, which clearly I don't, or I wouldn't be asking questions on this forum.

Re: Tube through surfcace body

TheCADWhisperer — Tue, 21 Apr 2020 14:35:11 GMT

@Anonymous wrote:
... if you have the required skillset, which clearly I don't, or I wouldn't be asking questions on this forum.

For whatever it is worth - I have been doing this for 30 yrs or so.

I would not use the stl for anything other than as reference in starting over.

Maybe I'm just don't have the required skill set for this stuff...

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 14:39:49 GMT

So you are saying it's not possible to edit this stl to add a tube?

Re: Tube through surfcace body

laughingcreek — Tue, 21 Apr 2020 14:50:08 GMT

what everybody is telling you is that fusion isn't good at manipulating triangulated mesh files. any workflow in fusion that involves converting the triangulated meh to a brep is a flawed workflow, and only works in for a very narrow set of circumstances (such as the ones AD shows in their videos showing off the mesh workspace in fusion). there are other workflows that don't involve the mesh conversion. it's helpful to have a foundation in both solid modeling in fusion, and mesh modeling in a separate program before attempting to combine work flows.

Even though it would be better to learn how to model from scratch, that's not what you want to do. So let figure out how to do what you want to do. ~~start by posting your fusion file with the .stl file in it~~. edit: oops, I see it now in your previous post

Re: Tube through surfcace body

laughingcreek — Tue, 21 Apr 2020 15:01:31 GMT

I just looked at your file. it's just a bunch of surfaces, no solids anywhere. how where you planning on making this? Your defiantly not 3d printing it with out a ton of work to fix it.

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 15:03:57 GMT

Thanks for your input. The stl prints perfectly. I have already printed it. However it doesnt have the required strength for the forces I'm going to put through it so I want to strengthen it with a longer carbon fibre tube the length of the wing.

Re: Tube through surfcace body

davebYYPCU — Tue, 21 Apr 2020 15:06:15 GMT

If you were of a mind to design the replacement, use round lightning holes, for increased strength. We all know about square corners....

The commercial kits use single perimeter printing, not sure if this is one of them.

Re: Tube through surfcace body

Anonymous — Tue, 21 Apr 2020 15:07:48 GMT

Pic of completed wing