Element/Surface shape in Freeform work space

[muhammad.abdulhadi20]

Hi,

I was wondering if it is possible have some polygon shape except rectangles as controlling surfaces/elements in freeform modelling. I wanted to model gemstones and the way I want to do it is by making a sphere with the element shapes as triangles, hexagons and pentagons and then applying Crease feature on the edges.

Another way of course, is by using the solid modelling but it is time consuming. Also, the reason I'm using this approach is because I'm new to freeform modelling. I have only done parametric modelling so far.

Now I have following two ideas in mind:

1- Projecting a sketch onto the surface of a sphere and if there is any feature(if I'm lucky) that allows making that sketch the controlling elements of freeform, I might be able to apply Crease feature and things will be very easy.

2- If it is possible to create surfaces using edges and vertices in the space, like selecting the target edges/vertices and program generates a surface using that input, I might be able to generate the gemstone profile by placing sketches on different planes and generating surfaces as said.

I have attached the photos of freeform spheres. It allows me to make control surfaces using latitude-longitude system and the other way shown is span faces. As I said before I want them to be triangular or other required polygons.

Kindly share your opinions and ideas on how I should create these gemstone profiles.

Cheers,

[laughingcreek]

The short answer is, t-splines don't work that way.  When modeling with them, it is best to stick to quads (4 sides).  triangle are to be avoided.

for some back ground, you might read up on sub-D modeling.  There are some notable differences between t-splines and sub-D models, but the general approach is remarkably similar.

I can't comment to much on modeling gem stones.  I use them a lot, but i either use one of the generic models that can be found online (try grabcad), or I am supplied the model as part of the description given to me by the dealer.

do you have a picture or sketch of what you need to model?  You'll probably get help with an approach if you post it. 

[muhammad.abdulhadi20]

Thank you @laughingcreek ,

I am an amateur in CAD and just started experimenting in freeform models. I just came up with the idea to make gemstones and thought why not use freeform as experiment and found crease feature, which prompted the ideas mentioned above. I wanted to make a common topaz or sapphire stone.

Now is it possible to achieve the result using any other of the above mentioned approaches? Like is it possible to generate surface by picking an edge and a vertex? Or using projected sketch to Crease the edges/Projected T-splines.

Also, I just looked up sub-d modelling and it seems to be the way I want to approach it. Can we do that in Fusion 360?

[laughingcreek · Accepted solution]

random thoughts in no particular order-

-If you are interested in a straight Sub-D type of approach, then Fusion/T-splines is not for you.  A free and very powerful alternative would be Blender.  There are also many other great options  for this type of modeling if you have $$.

-T-splines are not a great option for modeling flat surfaces with hard edges. (ie gem stones)  

-If you are looking to learn how to use and model in Fusion 360, DON"T START WITH T-SPLINES.  They look oh so simple, but require a lot of knowledge and experience to get them to look and function right.

-a gem stone can be modeled in the regular modeling space of fusion, and might make a good learning project.  the approach would depend on the specific geometry.  if you post some info maybe someone will help you figure it out.

[muhammad.abdulhadi20]

Thanks a lot @laughingcreek ,

I had no idea if it was possible to generate sub-d's and that was quite helpful of you.

Turned out the Fusion sketches are very flexible. I was able to create a sketch on a plane and then move the vertices perpendicular to that plane, which created a 3d sketch and then I simply used patch environment to create the gem, which is as follows( in wire-frame).

Just another thought: is it possible to model it using loft?

Thanks Again.

[laughingcreek · Accepted solution]

You can use solid loft, but you have to set up a bunch of rails to get it to flow properly.  It's probably easier to use the surface loft instead.  your on the right track.  multiple planes, cross section sketches on each plane.  here's a screen cast of one possible approach