Lofting between two parallel sketches (newbie question)

[vectorzero]

I'm trying to create a duct shape using lofting between two sketches in parallel planes.

I've created guide rails in the two orthogonal planes but can't get the shape I'm looking for. I'm very new to Fusion, so perhaps lofting is not the right tools for this.

If I selected the the top rail it gives me a centreline with the correct shape, but theottom edges then follow an arc, whereas I want the object to have a flat bottom.

Any ideas. Attached is a photo of the component I'm trying to recreate.Also attached is the 3d printed component folowing the arc.

My project is here. http://a360.co/1KeA6lu

[TrippyLighting · Accepted solution]

That shape can be created, but you need 4 instead of 2 rails. There are two main steps to this that help with creating the rails:

1. Projecting the corner points of the profile sketches into the rail sketch
2. Constraining the rail end points to these projected corner points.

I've created a little screencast that hopefully explains it better.

[vectorzero]

Thank you so much.

I now understand so much more about how to use the feature. Very much appreciate your time and the video.

[vectorzero]

I thought I had learned my lesson, but I've hit another bump. The top rail actually needs to follow an outward curve similar to the bottom curved rail. I've succesfully projected the bottom rail sketch to create a new 3D curve, but I can't constrain one end of this new curve to the original face. I'm missing a key piece of understanding here it would seem.

http://a360.co/1Dz57Zr

[Anonymous]

Hi there, before trying to do a complex loft like that, have you considered just creating a solid box, and two sketches, using each sketch as a Split Body tool upon the box, might give what you need?

I've attached the native .f3d file that you can download, then upload into Fusion.

Hopefully it helps!

Jesse

[Anonymous]

Regarding your new 3d curve in that picture, the way your workflow has progressed, you would need to define a new sketch onto the old profile sketch and create a new profile in that (using Project or Intersect for the 3d curve), because the 3d curve was made in time/timeline after the old profile sketch, so upon editing the old profile sketch, the 3d curve will not be visible. 

You'll get used to it 😉

Jesse

[vectorzero]

Thanks for the replies.

The issue with the subtractive approach is that the cuts result in 2d curved faces, whereas I want to achieve a 3d curved face on the outside edge.

I've now figured out how to do this by creating a rail using the intersection function. Will post a video to hopefully make this clearer to anyone reading the thread.

[vectorzero]

As promised here is the screencast showing how I did this. Here is the model used in the video for further clarity.

[Anonymous]

That's a nicely made video.  It's interesting that by projecting that corner point of the profile to make your "reference curve," that the resulting 3D intersect curve was perfectly intersecting that corner of the profile, so that you didn't have any trouble using the 3D curve as a rail (often with lofts will get a warning that a rail does not intersect the profile, so have to be very particular normally about using Intersect or Project and coincident constraints to that).  

Thanks!

Jesse

[Anonymous]

I forgot to mention just in case you didn't know, that the view can be rotated by holding down the shift button and middle mouse button (something similar on Mac OS).

Jesse

[vectorzero]

Thanks Jesse

I struggled for a while with the 3d curve NOT intersecting the vertices at each end. As a beginner the use of projections was hard to grasp, until the penny dropped.

Although the video quickly gets to the end result I think I should go back and reshoot it, focusing on the steps leading up to the creation of the curve, since the devil lurks in those details. Stay tuned.

[Anonymous]

That's awesome you want to make detailed easy to follow videos,  In fact right now finishing a new kind of interactive platform to help people learn this stuff easily - your project and video would be great to integrate into it. 

It's great to help people and be learning at the same time!

BTW, I also forgot to mention a curious feature of that view rotation by Shift + Middle mouse button, is that if you hold this combination for a second or so over an object, then release, a little red dot will appear indicating where new view pivot point has been created.  Then can repeat the combination to rotate about that point.

Jesse

[TrippyLighting]

Interesting. I thought that my screencast explained the point projection well enough 8-)

[Anonymous]

He he, you can't get much better than Trippy's videos.  I'm pretty impressed though how Vector made a 3D curve for one of the rails via an intersection of two 2D curves...I've never actually seen that used for anything before until now.  

Exciting times.  Exciting times 😉

[TrippyLighting]

Thanks!

I hope my German accent is not too thick. I have better and worse days. Sometimes I repeat a video 3-4 times and more often because I cannot stand hearing myself talk 😉

Vector sounds soo much nicer with his British accent. I am looking forward to his video as he has taken what I showed with the point projection a step further. It really shows very nicely what can be done when one nicely combines some of Fusions features.

[Anonymous]

No your accent is not bad at all, in fact to me German accents are cool because I've come across quite a few really smart Germans for some reason.  But that's interesting how some days you say the accent is more pronounced, I guess it probably takes quite a bit of brain power to suppress an accent, so probably depends on what you're eating, sleep, exercising etc.  And sounds like you're a recovering perfectionist too? (I've found it's not always bad to demand perfection though 😉 )

British accents are indeed cool as well.  I'd say for me it's a tossup between German, British, and...Russian, as to which is the coolest 😉

Indeed, the more familiar one becomes with all the tools at disposal, the more enjoyable it is to model things, gaining eventually a kind of second nature I guess to build just about anything under the sun 🙂