modeling a dome shape

[Jasper]

What are some methods to model a a surface that is convex in two directions, such as a dome or upside-down bowl? I am struggling to find the right Alibre features to use to achieve such a shape.

Thanks,
PJ

 

[NateLiquidGravity]

Draw 1/4 of a circle and thin wall revolve?

 

[DavidJ]

Draw semi-circle, revolve, shell, might also work.

 

[bigseb]

Draw a full sphere and cut half away. Shell.

 

[Jasper]

Thank you. I had forgotten about revolve. I tried revolve but I realize my problem is more complex than that. I am trying to model the rooftop of a trolley (i.e., train car). the roof is curved (convex) in one plane for most of its length, but at the ends the roof is curved in two planes (the ends are slightly domed). However, the radius on the end of the roof is much greater than the roof's cross-section, upon which the revolve would be based.
I've uploaded a sample. I can create a curved surface with a radiused end, but I cannot figure out how to dome that end. Simply filleting the edge doesn't give the correct shape.

 

[Wade Waterman]

Hi, Not sure if this helps at all? I was playing!

Wade

 

[idslk]

Hello Jasper,

do you pictures of the trolly or 2D drawings?

Regards
Stefan

 

[Jasper]

No drawings, just going off of photos of the original model. Here is a photo of the trolley in question, although this is a side view only and doesn't show the "dome shape" very well.

 

[Jasper]

Wade I can't open the file; I have 2018 but not updated to the latest version.

 

[idslk]

Hello Jasper,

I'm on the latest Version, so here for example:
- make a sketch on XY with a 2 straight lines, give them dimensions, than add a spline to close the sketch figure
- make a sketch on YZ , 2 straight lines, dimensions, spline to close.
- make a sketch on ZX , 2 straight reference lines, dimensions, spline from endpoint to end point
- Loft XY, YZ with Guide curve ZX
- Mirror the Loft
- New sketch on face , project the outer lines of result face and extrude.
- Now you can add a shell

Regards and good luck
Stefan

 

[Jasper]

Thanks Stefan I will give that a try tonight.

PJ

 

[Jasper]

Unfortunately this method creates a bullnose shape, like a fillet. I believe this is because the guide curve must begin and end on the two loft sketches.

 

[idslk]

Hello Jasper,

do you have better pictures?

Regards
Stefan

 

[idslk]

Hello Jasper,

should it look more like this?:


Regards
Stefan

 

[bigseb]

These sort of shapes... not really Alibre's forte. Design of this sort is best handled by Moi or Rhino in my opinion. No dimensions to work with so something along these lines?

 

[idslk]

Sunday afternoon here in Germany ...
Only Alibre Design!



Regards
Stefan

 

[bigseb]

Gut gemacht. How long did it take?

 

[idslk]

Hello Bigseb,

thanks for the flowers ;-)
I've seen your Roof, downloaded it, thought about it, had long lunch, done internetsearch for better pictures of the neighborhood trolly, thought more about it, designed and posted it ... 3 hours gone. At last it took net less than 40min.
It took the most of that 40 minutes for making the 3 splines looking smooth ...

Regards
Stefan

 

[bigseb]

Sounds about right. Moi took a little over 5 minutes. Because shapes like this are just so much easier in Moi.

 

[Jasper]

BigSeb: I came to the same conclusion. I have Moi but haven't learned how to use it. Your model is spot on.

Stefan: Your model is also spot on...How did you make it? Same as before with two lofts and guide curve? It would be faster for me to spend 40min in AD than learn Moi I'm sure.