Extract curve from surfaces or solids
The link to the model you provided does not appear to load a model.
You cannot simply 'extract" a curve. Depending on what application you are working with sometimes you can create iso curves on a surface (not in Fusion 360) but in this case you might extrude a surface from the spline you sketched (with tot many spline control points) and trim it with teh top surface and then use the trimmed edge for the pipe.
Accepted solution
what @TrippyLighting said, however
Link worked ok for me,
I replaced Fusions offset spline centreline, it did not reach the base line, and made a mess of the pipe.
Extrude a surface to object, highlighted top face, and send pipe along that edge,
Might help....
@jeff_strater Why would offsetting one chain of a 3 degree projected spline, result in 20 individually selectable splines?
Ok I say this once more 😉
In Fusion 360 you should absolutely NEVER offset a spline. EVER.
Extrude a face and offset the face.
Compare curvature combs on the offset spline vs the edge of the offset surface. You'll likely see immediately why I say this!
I might just not have been patient enough but now it downloaded. I almost with if didn't.
When talking about the internet and YouTube I told my kids that you never can un-watch something so be careful what you watch.
I can see the beautiful shapes you have in mind, but, MAN, your modeling techniques need some serious work. Those broken up splines almost caused temporary blindness 😉
Please come earlier with your models so we can guide you along the way!
@davebYYPCU - I'm not entirely sure, to be honest. A projected edge is a different kind of creature, and I wonder if its offset is just a reflection of that. It does seem odd, I agree.
Jeff Strater
Engineering Director
Tough ?
Here is the curvature on the intersection curve created in this model. I would call this unusable garbage!
I have many examples of this and some of them are much worse!
- Intersection curves from very smooth input splines
- Curves offset from perfectly smooth splines
- Curves projected from perfectly smooth edges
All have one thing in common. They create horribly broken curvature, which in turn creates bad surfaces that show artifacts when rendering and much worse sometimes result in modeling problems.
Almost all of this can be avoided if you work with surfaces instead of sketches.
Here is an edge created by simply trimming extruded surfaces to arrive at the same curved edge. Buttery smooth!
If you think I am tough then I would respond the same way Richard Feynman once did during his lectures about QED 😉
To support my other point about curves hacked together from several splines here is very similar geometry but with vastly improved curvature, all based on two input sketches, a circle and in this case a single, continuous control point spline. It takes a little bit of set-up and adjusting, but with proper care in Fusion 360 one can also create impeccable surfaces.
Continuing one can then create a very similar object without the need of any other sketch:
@Anonymous wrote:
Where do you think I'm wrong in my modeling technique?
You start by patching a relatively simple curve together from 2 different spines and then mirror that in a sketch.
I created a single continuous control point spline. This a a bit more work, but it is well spend.
If you start a model by creating good sketch geometry even when just prototyping a design , you will have. much easier time later on.
The intersection curve you created has bad curvature, something most Fusion 360 users are not aware of.
Then you projected that intersection curve, or an edge created by I back onto a flat plane breaking the curvature even more:
Then you offset that projected curve. That finally was too much for Fusion 360 and the offset curve is constructed from individual spline segments.
You built a succession of increasingly worse geometry. While this has not yet led to a problem in modeling, this model isn't far from it 😉
If you take a look at the file I had attached to my last post you'l see that all of that can be avoided.
Accepted solution
@Anonymous wrote:
Ok Peter,
I understand your words.
So, please an advice more: starting from an idea and not from a sure thing, in your opinion, it's better to draw a rough sketch of a basic curves or of a basic surfaces to see the rough result and then manual rebuild that initial curves/surface to have a good final solid: am I right?
Yes!
Design in my opinion and experience is a very iterative process. I often develop ideas while I am working on another idea. So sometimes my designs are also quite broken (pssst don't tell anyone ) . However, I know Fusion 360 so well by now that I know when it is time to re-build a model, or even to take int into another CAD system and continue there. Each tool I use has its unique strength.
As someone who just starts out in Fusion 360 you don't have that experience yet so the intention behind my post is to introduce you to different and sometimes better techniques.
So to answer your question, yes! If you just wan to quickly visualize and idea and see if it look like you hoped, then rough modeling is fine, but you still need to check the quality of the curves, edges and surfaces, so you get a feeling for when it's time to re-build the model.
As to Dave's technique, I believe I have clearly explained why offsetting and projecting splines in Fusion 360 is often not a good idea. For a final model I personally would, offset the spline but only use it as a visual guideline to manually create a "clean" curve.
@Anonymous could you mark Dave's and my posts as solutions so we can close this thread ?