topic Re: How to Combine A LOT of Splines into One??? in Fusion Design, Validate & Document Forum

How to Combine A LOT of Lines into One???

Fab_Things — Tue, 02 Apr 2024 17:14:30 GMT

The sketch I am working on has about a bajillion individual lines (~~splines~~) that I would like to combine into more meaningful segments. It seems like a very simple operation, but I cannot figure out how to do it despite a lot of internet and CAD forum searches. Does anyone know how this can be done?

Re: How to Combine A LOT of Splines into One???

TheCADWhisperer — Tue, 02 Apr 2024 16:46:17 GMT

@Fab_Things

If this were my work I would use the sketch only as reference in recreating a new sketch.

I doubt that any Splines are needed.

I would probably not put the smaller fillets in the sketch but rather as placed features.

Fortunately it is relatively simple sketch...

I started for you (see Attached).

Re: How to Combine A LOT of Splines into One???

HughesTooling — Tue, 02 Apr 2024 16:45:03 GMT

The sketch is made from only lines, no arcs or splines at all. Where did the sketch come from, does the program have any options for exports?

Re: How to Combine A LOT of Splines into One???

Fab_Things — Tue, 02 Apr 2024 17:15:14 GMT

@HughesTooling

Thanks for pointing that out. I am new to CAD and got that reference to splines vs. lines mixed up. I edited the OP to reflect this.

This is from an inserted mesh (stl) file that I then projected the outline of and broke the link so I could modify the outline sketch. I don't know what program was used to create the stl file that I am using as a geometry reference.

The posted file is only a portion of the overall design. And there are other stl files I need to go through the same exercise with. I've been manually deleting lines and extending remaining ones and it is taking forever! Combining lines should be a fairly simple thing to do, especially for a CAD program. How can that be done in Fusion?

Re: How to Combine A LOT of Splines into One???

Fab_Things — Tue, 02 Apr 2024 17:08:05 GMT

@TheCADWhisperer

Thank you for starting the recreation. Problem is, there are other stl files I need to go through the same exercise with. I've been manually deleting lines and extending remaining ones and it is taking forever! Combining lines should be a fairly simple thing to do, especially for a CAD program. Is there any way that can be done in Fusion?

Re: How to Combine A LOT of Splines into One???

g-andresen — Tue, 02 Apr 2024 17:11:53 GMT

Hi,

1. several lines cannot be connected to form a single line.
2. try the divide and conquer method
3. the sketch is of poor quality, as evidenced by the lack of tangential transitions, for example.

(view in My Videos)

günther

Re: How to Combine A LOT of Splines into One???

TheCADWhisperer — Tue, 02 Apr 2024 17:14:17 GMT

@Fab_Things

You could use the PE Join commands in AutoCAD - but the trouble is the original geometry is rubbish.

You will want to use only as reference in creating clean logical geometry from scratch.

Re: How to Combine A LOT of Splines into One???

Fab_Things — Tue, 02 Apr 2024 17:22:49 GMT

@TheCADWhisperer

Yeah, I agree the original geometry is not crisp by any means. I was hoping to avoid manually retracing all the outlines I need to convert (i.e. there are other stl files I need to do this with). I can't believe Fusion doesn't let you combine lines!! It would be easier to correct the existing geometry if the lines could be combined into meaningful segments vs. redrawing everything. 😐

Re: How to Combine A LOT of Splines into One???

TrippyLighting — Tue, 02 Apr 2024 17:36:42 GMT

@Fab_Things wrote:

@TheCADWhisperer

... I was hoping to avoid .... I can't believe Fusion doesn't let you ...

.stl files do NOT contain native CAD geometry. .stl files contain triangulated meshes and, as such, are the least common denominator to represent 3D geometry.

As such they are about the worst geometry to work with in most CAD software and are terrible as a beginner project.

Period!

Re: How to Combine A LOT of Splines into One???

g-andresen — Tue, 02 Apr 2024 17:42:17 GMT

Hi,

@Fab_Things wrote:

It would be easier to correct the existing geometry if the lines could be combined into meaningful segments vs. redrawing everything. 😐

This does not mean that you can avoid adding constraints afterwards (e.g. tangency).
Such actions will then certainly lead to disturbances in the profiles and probably even to chaos.

günther

Re: How to Combine A LOT of Splines into One???

laughingcreek — Tue, 02 Apr 2024 17:55:14 GMT

@Fab_Things wrote:...This is from an inserted mesh (stl) file ...

I agree with the advise to manually recreate this. That ends up giving the best result for about 90% of the use cases involving mesh files.

but

have you tried "create mesh section" (in the mesh work area) followed by "fit curves to mesh section" (available when editing sketch created for the mesh section)?

Re: How to Combine A LOT of Splines into One???

Fab_Things — Tue, 02 Apr 2024 17:56:17 GMT

@TrippyLighting

I understand that about stl files. If Fusion let you combine lines though, because I can extract the needed profile sketches from stl files, working with the stl files as a reference would be much, much, much more efficient. Most 3D handheld scanners, from what I understand, create stl files so the ability to combine lines would be a very useful feature in Fusion.

Re: How to Combine A LOT of Splines into One???

TrippyLighting — Tue, 02 Apr 2024 18:10:46 GMT

@Fab_Things wrote:

@TrippyLighting

...so the ability to combine lines would be a very useful feature in Fusion.

The facets, or, in your case, the individual lines projected from these facets, approximate a curve, or multiple connected curves, not a line.

Fusion 360 does not have a toolset to re-create on or more curves from these individual line segments, and that is indeed not trivial!

Some CAD tools do have that ability, and try to create one or more "best fit" spline curves through the number of line end points. But that would likely fail on too many short line segments.

Re: How to Combine A LOT of Splines into One???

TrippyLighting — Tue, 02 Apr 2024 18:19:40 GMT

@laughingcreek wrote:

have you tried "create mesh section" (in the mesh work area) followed by "fit curves to mesh section" (available when editing sketch created for the mesh section)?

I'll take back what I said in my post about how Fusion has no tools to do this.

I keep forgetting about the mesh section tools 😕

Re: How to Combine A LOT of Splines into One???

Fab_Things — Tue, 02 Apr 2024 18:39:38 GMT

@laughingcreek

Yes, I have tried that. Still playing around with that approach while also trying the approach in the OP.

Thanks for pointing that out though as I only discovered those mesh tools a couple of days ago!

Re: How to Combine A LOT of Splines into One???

TheCADWhisperer — Wed, 03 Apr 2024 00:43:01 GMT

@Fab_Things wrote:
Combining lines should be a fairly simple thing to do, especially for a CAD program. Is there any way that can be done in Fusion?

@Fab_Things

I got sidetracked by your sketch.

There might very well be a way to fix this up in the commercial license of Fusion (not in free personal license) but need the original *.stl file, not your sketch file.

Re: How to Combine A LOT of Splines into One???

Fab_Things — Wed, 03 Apr 2024 06:17:07 GMT

@TheCADWhisperer

Thank you for exploring this further!

Original .stl file attached. Along with the fusion file I inserted it into and projected its profile that still has the projection link.

Re: How to Combine A LOT of Splines into One???

TheCADWhisperer — Wed, 03 Apr 2024 12:37:02 GMT

Senior moment here - for some reason I cannot generate Mesh Face Groups on this.

Am I missing something?

Edit: Never mind, I got it if I didn't use Quick...

Re: How to Combine A LOT of Splines into One???

HughesTooling — Wed, 03 Apr 2024 12:39:33 GMT

Seems to work for me. Don't think this will work too well though because the fillets everyware tend to make it difficult to get useful faces. I needed to reduce the angle threshold to get this but because of the fillets the triangles around the flat fate are almost tangent.

Re: How to Combine A LOT of Lines into One???

TheCADWhisperer — Wed, 03 Apr 2024 12:46:58 GMT

@Fab_Things

I didn't take time to try to Edit Face Groups to get better results - but see Attached...