Need help with ellipses

[whippersnapper02]

I've been using Fusion 360 for about a week in designing waveguides for the tweeter of a loudspeaker. Here is an example:

http://s139.photobucket.com/user/augerpro/media/JBL.jpg.html

The waveguide always starts as a circle at the tweeter dome. It then can stay a circle, or become an ellipse like the above pic. I'm having no problem designing the circle version but designing an ellipse has me stumped. Here is a finished example of a circular waveguide I just finished:

http://s139.photobucket.com/user/augerpro/media/wg5.png.html

Easy to do by just making a cross-section of the wall and revolving it. For the ellipse I first tried lofting between the circle and ellipse and it worked ok except the top was closed and I'm not sure why (it wasn't checked in the window). So I then tried to make two cross-sections of the wall like I did with a circular waveguide and trying loft to "wraparound". I could not get this two work with any combination of settings, for example I thought using centerlines and picking the ellipse or circle would work but no go. 

Any advice on how to accomplish this? 

[davebYYPCU]

I have attached a file with a surface and a solid model of a revolved ellipse,

the solid one may be what you got, I then made a shell of it to simulate.

Size to suit your need in the sketch.

Browny

[whippersnapper02]

Thanks, but that won't really work for what I need. Did you see the pics I linked? Think of a funnel where you transform from a circle opening on one end to an ellipse on the other. Also the walls are curved so it flares out. I've attached one of my failed attempts. I tried shell to get it to open with some success, though not perfect. After that I failed at building the flange with screw holes as seen in one of my links above.

[davebYYPCU]

Ok I missed that it was convex,

You have a solid in that result, shell the top and or the bottom faces away, and you are left with a thin wall funnel

Or use the Patch method for loft and it wont be a solid, would need to be thickened,

so 6 of one, half dozen the other

To flang it, create a profile and a path sketch to sweep,

then holes, or pattern a holes you desire in the flange.

Browny

[whippersnapper02]

Thanks for the feedback!

Do you know why I have a solid on top? I don't understand why it forms, I don't have "close" selected when I loft. I did try shell on the top surface and it mostly worked, missed a bit towards the edges where the flared wall is tangent to ellipse sketch. In the real world it would probably print ok, still I'm not sure why even have to deal with it being solid.

I'll look at the patch method. I need to thicken the walls to .25" anyway.

I did try making the flange how you mentioned but i think the part I'm missing is making/selecting the path to sweep. I'll look into it.

Thanks!

[davebYYPCU · Accepted solution]

You got a solid result because you are working in "Model" top left of the screen,

Go to Patch in that drop down,

select the profile and rails the same way and you get a surface version.

Check your dimensions, I have fiddled my end and the shell was presentable with 0.1" - 0.25 looks wrong,

For 3D printing you can go to 0.0625.  Depends on settings in the slicer for hollow stuff.

Sweep path is a new sketch as an ellipse that will just cover that tangency problem.  Make sure you attach the flange profile to this path.

Browny

[whippersnapper02]

Loft in patch and thickened work great! (Had to trim some ends because of the way it thickens but that was easy) 

I'm trying to add that flange but I must be missing something in your explanation. I sketched a new ellipse, then made a profile that was touching the ellipse - is this what you mean by attach? Anyway when I revolve it is circular. See my link.

http://s139.photobucket.com/user/augerpro/media/ellipse.png.html?sort=3&o=0

[whippersnapper02]

Gah I figured it, silly me! Thanks so much for the help!

[davebYYPCU]

Sounds like you almost got it,

Not revolve, "Sweep"" command, select the flange profile, then the ellipse as the path,

This my fiddle file,

Browny