Fusion 360 Tangency w/ Splines

[Anonymous]

I'm unable to make tangency with lines and splines.

One can make with arcs/ cricles and splines but only to handles.

Any workaround / idea on how to solve this?

Regards

Gonçalo

[HughesTooling]

As you've found you can only add the tangent at a fit point and the only workaround is to add a fit point where you want to create the tan point. Because Fusion's sketches are parametric if you add a tangent between a line and a spline the line almost becomes a handle so moving it adjusts the spline and editing the spline with affect the line.

Tangents between splines and Arcs\Line has been requested, don't know when they'll be added.

Mark

[Anonymous]

Hello Mark,



Thank you for your quick answer!

I'm a product designer and I work mainly with splines in sketch mode.

Splines has to be parametric, no question about! Anyway, it can still be
tangent to a reference orthogonal construction line that defines a limit,
for instance.

This is a big issue to solve in terms of workflow. Otherwise we have to
workaround with additional geometry, seeking how to find the tangent.



Another thing I’ve noticed is that we cannot define different lengths to
curvature handles in the same point. Why they have to be symmetrical in
length?

I should be able to control the curvature tension of a spline segment,
depending on the handle's length, without affecting the opposite handle of
the same point.

Splines also should be able to work free in 3Dsketch. I didn´t yet
understand how to work with. However, constrain a handle to be parallel or
“follow along” a origin axis should be possible.



This issues makes the spline tool in Fusion very limited compared to other
parametric CAD software.

Maybe I'm too used into other CAD software that have all of this in a simple
way, in my point of view.



Hope to find this type of functionalities in spline tool in Fusion 360
updates.



Best regards

Gonçalo Justino

[HughesTooling · Accepted solution]

Hi Gonçalo

Just a bit of background. Fusion uses a sketch solver written by the fusion team, a lot ot the other parametric modelers use the D-Cubed licensed library from siemens so the Fusion sketcher has some catching up to do. There are improvements to splines promised, don't know when we'll see them though.

Not sure if the problem with non symmetrical handles is down to the type of splines or other software hiding how they do it. Imported splines from illustrator for example are split at points where the curvature is not symmetrical. You can do the same in Fusion using 2 splines, add a tangent between them and you'll get the ability to adjust the handle at the end of each spline independently.

3d sketching in Fusion is pretty limited, to edit a spline you need to use the Move tool. Pick a spline fit point or activate a handle and select one of it's endpoints, right click and select move and then drag. If you have fixed points use several sketches on different planes then create a sketch that will contain your spline, use Project Include 3d Geometry to include the references from the other sketches then add constraint to your spline. See attached file.

Mark

[Anonymous]

Hi Mark,

I've noticed that Fusion Team made very important improvements on spline tool.
The new "Control Point Spline" is a very good step to workaround unsyimmetric handles on control spline points - for me, this is a much free and easy way to obtain the required curvature.
Still, I think it lacks the ability to constrain tangancy with splines and another sketch geometry (lines, arcs, other splines, etc.) - please see the image attached.

As you can see, the curvature is similar in both examples, but not exaclty de same!
With the new spline tool, the curvature is more relaxed and easy to get. However I dont see any possibility to constrain it withal my construction limit.
Probably, the ideal thing would be mix the two types of splines in one tool! I leave the idea...

[mroek]

While I am very happy that CV splies are finally implemented, I am disappointed that they are more limited than what I had imagined. Your example shows that quite well, where you want to drive the control points from a tangency to other geometry. I suppose that's a difficult thing to do, but shouldn't it be possible?

But what's more disappointing is that you cannot add tangency with other geometry at all (except at the control points), which I thought was going to be possible. This makes the CV splines less useful, I think. For the older splines this could be worked around by adding a fit point where you needed the tangency, but I don't see any way of doing that with the CV splines (but I may be mistaken).

@jeff_strater: Could you perhaps comment on this, and whether improvements to CV splines are in the pipeline?

[jeff_strater]

@mroek, thanks for the feedback.  Yes, there are certainly limitations in CV splines.  We had to make a choice whether to release the basic functionality, which has been requested for a very long time, vs. delaying even longer trying to support everything.  We chose the former.  This is a common theme for us, and always a hard choice to make.

Your analysis is correct - supporting a general tangency constraint between a spline at any point, and other geometry is challenging, otherwise we would have done it much sooner.  We will evaluate this requirement against other priorities, but recognize that it is an important one.

[mroek]

@jeff_strater: Ok, thanks for letting us know. I hope improvements to CV splines can be prioritized, because they will really be way more useful if more constraints can be used.