"Loose" Loft

[Anonymous]

Hello everybody,

I'm new to Inventor (used to Rhino 3D) and was wondering whether there is some kind of function like the loose loft in Rhino?

When lofting over several section curves in Rhino, the loft command allows the user to handle how every section is treated. If a "loose" loft is created, the section curves are not met 100% by the created loft. They have some kind of influence however (like they are "pulling" with a certain weight at the surface). Is there some kind of function in Inventor as well?

Cheers

[CCarreiras]

Hi!!

Yes.

You can add new sketch rails to influence the loft between profiles.

you can add tangency with "variable force" at the start and end of the loft in loft conditions tab

You can tweak how the profiles connect beteewn in the loft transitions tab

[PaulMunford]

There is no option to control the inner curvature of a loft in inventor (i.e. at the lofted profiles).

You might be better off reducing the number of profiles and controlling the curvature with a center line loft?

[Anonymous]

@PaulMunford Controlling the shape by a centerline unfortunately is not really an option for my project. It really seems that Rhino has done something here that no other software is capable of doing...

[PaulMunford]

Well - if you want approximations, maybe!

Inventor is designed to give highly precise outputs - which demand highly precise inputs.

Post your part file with details of the problem you are trying to solve and we'll see if we can help you further.

Paul

[Anonymous]

@PaulMunford Paul, thanks for your help. Much appreciated!

I can't post the part-file right now, since I'm using a different computer.

I am aware of the fact that most CAD programs try to be as precise as possible (which obviously is their main purpose).

What I need to do is, to be "unprecise on purpose" in shape creation. Meaning: I want to create a surface that goes roughly through section curves (splines). After creating that surface, I need to be able to edit the weight of each section (=how it influences or "pulls" the surface).

Up to this point I would be better off with some sort of design software. However, now I want to use this surface in a parametric CAD model to create complex projects including this shape. Therefore, I need the shape to be parametric (=not a "dead" surface) so if I change it later on, everything I've created after that point changes as well.

Any ideas?

[TheCADWhisperer]

If you are using a later version of Inventor - you might want to investigate the Form tools.

[PaulMunford]

That's not to difficult.

I think that it just takes an adjustment in thinking. In Inventor we would make the geometry precise, and then add randomness by adjusting the parameter values.

I've put together an example screenshare showing how this might work.

It is a rig of splines controlling a lofted surface. Each spline node has the option to adjust it's height, angle and weighting.

I've used an iLogic form to control the parametric values - you don't have to do this but it does allow you a nice workflow to make adjustments visually.

[Anonymous]

@PaulMunford thanks again for your help.

I've had a good look at the video and your answer and I think that you already pointed out the mayor issue: Making the geometry precise and then adding randomness.

For what I'm intending to do, this approach is backwards and defeats the purpose (e.g. faired, smooth surfaces would be much harder to achieve, since they would require much more work)

[PaulMunford]

Well, If you can post a example of what you need to achieve (In Rhino format if necessary) we will see if we can help you further.