Combine / join 2 spline curves to a single one

[Anonymous]

There is "Break" operation in Sketch menu. So, I draw multisegment spline, then a line, and then split my spline by this line in intersection point. After that I have 2 connected splines.

So, the question is:

Is there the reverse operation except "Undo" to have these 2 splines to be single again?

Of course I can constrain the joint point to have these 2 splines Tangent, Smooth, whatever. But will not return the single spline. I.e. I cant apply "Close spline" to close the gap between 2 splines.

In addition, I faced with another problem when I have 2 connected splines:

It's tricky a bit to get "Tangent handle" for one of splines in joint point. For one of curves it appears just after clicking on the curve or endpoint. But for the second curve it does not appear after clicking on corresponding spline. Even if I click on the endpoint, the handle is shown for another spline. So, I have either to move the joint point, or click on other point on selected curve to see "Tangent handle" which I need. See screencast.

[Ben-Weiss]

For generative outcomes, we talked about merging splines in a recent Autodesk University talk (25:06 in the video; there are also step-by-step instructions in the handout). I tried to build a Fusion add-in to automate this procedure, but right now the API support for boundary splines doesn't do what I need.

[therealsamchaney]

I agree it would be very useful to be able to join 2 splines. The main reason for this is that when using a spline as a rail for a loft, there has to be one spline that touches all of the profiles and there is no way to select multiple curves as one rail. Many times I want a loft based on mirrored profiles so I could make a spline that goes through half of the profiles, mirror it, and then join the mirrored splines into one. That way I would only have to apply constrains and dimensions to one half. However, since I can't join two mirrored splines, I have to make one long spline across all of the symmetrical profiles, which means I have to double any constraint or dimension I apply to one side of the spline and its control points and handles. This makes adjusting the rails very tedious as every time I change something on one side, I have to go change the same thing on the other side.

[Claus_J]

This request is top of my list too. If arcs and lines could be converted too and everything could be joined and edited we would have an Adobe Illustrator kind of experience.

[hal54]

Yep, I too wish you could "join" separate [though closed and coincidental] splines. When you extrude a shape from a number of splines, you get vertical lines in the extrusion that coincide with the places where separately joined splines are made coincident. These vertical lines affect the filleting function; a fillet can act totally differently in an extrusion where these vertical lines exist. I hack this by converting the shape formed by the multiple splines into a construction drawing. I then draw a single spline, with only one beginning and end, trying to make it as coincident as I can to the construction lines. That way my extrusion only has one vertical line, where I close the spline shape, and I can control where this is so as to not have it affect the filleting. I notice some quite snide commentary above about the original request. [Don't be snide, we are just seeking help and guidance.] So, if I am not understanding something, and I can get the same fillets happining between two [nearly] identical complex shapes, one from a single continuous drawing and one made up of a number of separate splines, please tell me. The Vetric software has a "join vectors" function which would give me exactly what I want. I cannot seem to do this in Fusion. Thanks and stay save, this post being in the "Year of the Covid."

[TheCADWhisperer]

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@hal54 wrote:

;....a fillet can act totally differently in an extrusion where these vertical lines exist.

... we are just seeking help

So, if I am not understanding something, ...

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Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

[jelen.spam]

Seriously? Who said both curves are his... It is not a bug in a workflow it's terrible UX design of the whole Fusion 360. More I am learning how Fusion 360 works, more frustrated I get. It's missing complete basics or they are there but extremely complicated for no reason other than bad UX design.

[TheCADWhisperer]

@jelen.spam 

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

[kandennti]

It is possible to merge two splines and create a new spline using the API.

https://forums.autodesk.com/t5/fusion-360-api-and-scripts/convert-multiple-lines-into-a-single-splin... 

It would also be possible to create such an add-in.

[TomFreyTulsa]

I need to join two splines for the purpose of using them as a continuous rail for the loft command.

[TheCADWhisperer]

@TomFreyTulsa 

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

[laughingcreek]

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@TomFreyTulsa wrote:

I need to join two splines for the purpose of using them as a continuous rail for the loft command.

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No, you don't.  you can make a rail for lofting out of multiple splines without "joining" or "combining" them. they do have to be at least tangent though.

export your model as .f3d and attach to get help.

[morgan_darryl]

This is an old thread I know but michallach81, not everyone is designing their sketches from scratch.  For instance I reverse engineer my sketches from carbon fibre frames that I photograph on a white background to make a silhouette, clean them up in Photoshop, then use Inkscape to scale to frame size and use the trace bitmap command to be able to create an SVG of the frame.  I then import this into Fusion as a sketch profile.  However these SVG files are made up of many individual curves which are a right PITA to select at times.

While I realise that actually joining curves, especially splines could affect there original shape, a workaround to this would be the ability to group lines, arcs, curves etc so they can be treated as one element.  I'm aware you can create selection sets but this is not what people are looking for I guess. 

[MichaelT_123]

Hi Mr Morgan_Darryl,

.... consider checking the new sketch constraints member <curvature>.
Perhaps it will give you the functionality you want.

Regards

MichaelT

[morgan_darryl]

I loaded the SVG and selected one of the curves and tried to use the curvature constraint on an adjacent curve and the following error was generated:

Failed to solve.  Please try revising dimensions or constraints.

I've just tried experimenting with some of the Fusion 360 primitives.  If you have two seperate "Fit Point Spline", and apply this constraint it will adjust the curvature where the two splines meet as expected.  However they are still two seperately selected splines.  The main issue I have is my imported SVG profile is made up of many lines/curves and as I said it would be nice if they were as one.  I even tried using the union and combine paths in InkScape but this didn't solve the issue.  The best workaround I have so far is to create selection set for the individual lines/curves but they're still seperate entities rather than one continuous path.

[g-andresen]

Hi,

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@morgan_darryl  schrieb: The main issue I have is my imported SVG profile is made up of many lines/curves and as I said it would be nice if they were as one.  

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1. Without being a phrophet, I dare say this will not be the case in the future either.
2. If you import your template as a canvas into Fusion instead of Inkscape, calibrate it and create your outline over that template, you have the ability to add constraints.

günther

[morgan_darryl]

lol sounds like the standard response everyone gives on here.   Just use the original outline as a template to create a new sketch ✍️.   Seems a lot of work for nothing to be honest.   I’ll just create a selection set from now on, so that I can select all lines/curves from the SVG as one.   

These SVG I’ve made of carbon fibre frames, I’m extruding and then build new models around these frames (tpu components).   I don’t have the time :mantelpiece_clock:️ to be recreating the outline from scratch.   I originally used to trace a bitmap within Fusion but now use the SVG method to speed up my workflow, not slow it down. 
Rhino :rhinoceros: had the ability to do this back in like 2000 🙄🤣

[g-andresen]

Hi,

Just this much:
I did not write that you should do something twice, but that you should not trace the silhouette in Inksape, but in Fusion.
The reason for this:
Every imported sketch, whether in DXF or SVG, appears in Fusion without dimensioning and information such as perpendicularity, tangency ....

günther

[morgan_darryl]

I don’t manually trace the bitmap in Inkscape there is a function in there that will trace a bitmap and create paths that can be saved as an SVG.   There is no manual work involved.

I used to import the bitmap into fusion, calibrate and trace it manually but this is a tedious process and was never that accurate I found compared to the newer method I’ve adopted.   Bearing in mind each frame I have is made up of about 5-6 unique carbon fibre components.   To manually sketch those 5-6 components in accurate takes a lot of time and I have currently 10 unique frames.   So that would be 60

components to manually trace.   That’s before I get started creating the models to go on these frames, which is usually around 5 models per frame that I create from scratch.   Do you really think manually tracing the frame is a good idea when the likes of SolidWorks, Rhino etc all have auto trace features 🤯

I've included a few photos, this show the arm component that I've imported into Fusion as an SVG from a photo that I traced in Inkscape.  From that arm component I'm able to create TPU arm components that protect both the CF frame and the BLDC motors.  These components are printed using a Bambulabs P1S.  I'd like to at some stage go into designing more components but hand sketching the frames is a time consuming task, on top of the time it takes to model all of the TPU components.  Bearing in mind this is just something I do in my spare time and have a day job 😉

[TrippyLighting]

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@morgan_darryl wrote:

I don’t manually trace the bitmap in Inkscape there is a function in there that will trace a bitmap and create paths that can be saved as an SVG.   There is no manual work involved.

That is a workflow that has been suggested in a number of threads over the years.

I believe the oldest thread with that workflow is 7 or 8 years old.

It certainly helps with some workflows!

We mostly suggest manual tracing because there are hundreds of threads where imported .svg and .dxf files create problems. Profiles aren't closed, near tangency and near coincidence problems. Etc.

In many cases, manually tracing is the best option. 

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@morgan_darryl wrote:

Do you really think manually tracing the frame is a good idea when the likes of SolidWorks, Rhino etc all have auto trace features 🤯

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Yes, if you only have Fusion available to you, then clearly it is 😉