How to Loft Between Hollow Solids

[bahret]

Hi Everyone,

I'm pretty new to CAD, really only working in TinkerCAD for my 3D prints until lately when I decided to work in Fusion 360 a bit for some more advanced stuff.  I'm sure this is incredibly simple, but I just cannot figure it out, and I've spent a long time on it.

In short, I have two hollow solids, and I'm trying to loft between them,  I've read that I need to create an outer loft and an inner loft as a cut, and that makes sense, but I cannot figure out how to do that.  I can only select the faces themselves as the profile.  Selecting the edge just selects it as a "rail" and does not appear to do anything.

I'm able to select and loft between the edges in the surface tab, but then I need to figure out how to fill that, and I'm having trouble with both Boundary Fill and patch, likely because I am just out of my depth here and understand very little about surface modeling.

I was able to get a workaround to this by lofting the entire thing as a solid and then using Shell to get what I want, but that won't work in instances when I need the loft to bridge different thicknesses, plus it makes it harder for me to calculate sketch geometry as I prefer to make positive or negative offsets depending on if the design is going in or out of something else.

Anyway, I'm sure I am overcomplicating it.  If someone can tell me a way to do this, I would be grateful.  I'm happy to upload the source files if necessary, but it's literally just two hollow cylinders of different sizes separated by 25mm or so.

Solid Loft Error

[TheCADWhisperer]

Shell for uniform thickness.

For all others - 

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

This would literally take you less time than it would for someone here to recreate for you.

[bahret]

No problem.  Attaching it here.  Thanks!

[TheCADWhisperer]

I would do this geometry as a Revolve, not a Loft.

[bahret]

Thanks, this is helpful.  Going through these now.

[bahret]

Wow.  You are insanely efficient at Fusion 360.  I cannot believe you put all three of these together that quickly.  😮

All three seem to do what I need, so thank you.  The revolve option looks interesting.  I've shied away from that in the past because I am still getting better with constraints and such, but it looks so elegant and easy to change the sketch geometry.  I might have to go that route in the future.

I noticed that with the loft, you are deleting the two faces that the loft attaches to.  Is that just to convert the two solid bodies to surface models so that you can stitch everything together as one body cleanly?

[jeff_strater]

yes, this is just a fundamental limitation in Loft - it will not do hollow sections.  This is something that we are planning to try to address, at least in simple cases like this, this coming year. 

"I was able to get a workaround to this by lofting the entire thing as a solid and then using Shell to get what I want, but that won't work in instances when I need the loft to bridge different thicknesses, plus it makes it harder for me to calculate sketch geometry as I prefer to make positive or negative offsets depending on if the design is going in or out of something else."

The usual workaround for this is to do two lofts:  One as a solid, and a second as a Cut, just for future reference

[bahret]

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@jeff_strater wrote:

yes, this is just a fundamental limitation in Loft - it will not do hollow sections.  This is something that we are planning to try to address, at least in simple cases like this, this coming year. 

The usual workaround for this is to do two lofts:  One as a solid, and a second as a Cut, just for future reference

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Thanks, Jeff!  That's great to hear that you can help out newbies like me!  😁  If it isn't too much trouble, can you explain how I would do the two lofts in my case?  I cannot seem to select the edges to make the new lofts, only the entire face.  I can only do select edges in the Surface tab with methods like @TheCADWhisperer did above.  Should I be able to accomplish this in the Solid tab as well?

[jeff_strater · Accepted solution]

you have to add sketches to be able to select the inner profile.

[bahret]

Very helpful, thank you! The missing part for me was the extra sketch profiles. I appreciate you showing the direction vs connection method as well. Seems like it makes a more elegant loft that way. Thanks again!

[Rhynri]

Signed into the forums just to thank you for the video.  I have trouble understanding a lot of the guidance in these threads without a visual to associate it with.