How to model a freeform spherical structure? 1

[bdurack]

I want to create a sphere with a very freeform structure, with the same sort of pattern as in this 3D printed cast:

http://cdni.wired.co.uk/1240x826/a_c/cast1.jpg

I am using siemens nx 9 and have tried creating a sphere and a sketch with the pattern I want mapped over the sphere so I can subtract it from the sphere. I have tried using wrap/unwrap tool which works very nicely for simple curves like cylinders but not complicated curves like a sphere.

What is the easiest way to achieve what I am looking for? Any feedback would be great!

 

[JohnRBaker]

Attached is an example of how you might get started on something like this but without an idea of what the actual 'pattern' looks like that is about as far as I can go.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[bdurack]

Hi,

Firstly, thanks for the reply! This example is impressive and I can see how you've achieved this. It seems a lot of the advice I'm finding online is to do with wrapping a curve (sketch) to a cylinder first.

What I am trying to achieve is not uniform though and so couldn't be patterned like that I don't think. I am actually unsure as to how I would create my pattern as initially I was thinking of simply creating a sketch which I could then wrap around the sphere and subtract it from the sphere.

The sphere I am looking to model is shelled though as you have yours (1.5mm) and I was looking to create a lattice type structure as seen in the image I attached initially which would have walls of 1.5mm-3mm in thickness. I found this skull online (which is far more intricate than what I am trying to create) but is vaguely what I am trying to achieve, just as a sphere and with a pattern more similar to the cast in the first image I posted.

http://cdn2.ahalife.com/assets/uncategorized/119000079500-original.jpg

Does this make what I am trying to achieve any easier to understand?

Thanks again for the help

 

[JohnRBaker]

You do know that you can draw spline curves directly on the face of a model, including a sphere, using 'Curve on Surface' as well as 'Offset Curve in Face'. And for the future, we're working on adding support for 'sketching' 'Geodesic' curves on surfaces which will provide some additional capabilities, but that code won't be operational for awhile yet (but NOT as part of the initial version of the NEXT version of NX).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[bdurack]

Hi thanks for the reply!

I used splines in my undergraduate to create complex curves. I think this was probably in a limited way though. I have just used the curve on surface tool to create a rough shape on the surface of a shelled sphere. When I tried to extrude the spline I created it didn't work though. Is there any tutorials I can follow that do what I am looking to do? Sorry to be so vague again, I really do appreciate your help!

 

[KhimaniMohiki]

create a sphere, extract the surface of the sphere
Draw a lattice of curves on the extracted sphere sheet body
offset each curve in face symmetrically (so you get an offset curve either side of the original)
trim the sheet body sphere to the offset curves, selecting the regions to be kept/discarded
thicken resulting trimmed body
fillet corners of apertures
fillet edges of apertures

Khimani Mohiki
Design Engineer - PENSO Consulting Ltd

 

[bdurack]

Hi khimani

Thanks for the reply! These steps sound so simple and straight forward and yet I can't seem to get my head around it. I'm quickly realising how limited my NX knowledge is. Are there any tutorials that would show me the basic steps to do these things so I can apply them to do what I am looking to create? Or would you mind uploading a part file of what you are explaining so that I can go through the part navigator and seen what you have done.

Sorry, I probably come across so thick

 

[KhimaniMohiki]

Sorry Im not on NX at my current assignment but im sure someone else will be able to help, there are more than a few ways to get whats your looking for.

Khimani Mohiki
Design Engineer - PENSO Consulting Ltd

 

[Arkance/PhoeNX]

Here's a video of what Khimani suggested.
Apologies for the picking errors, my son rang me just after I started recording the video.

Anthony Galante
Senior Support Engineer

NX5.0.6, NX6.0.5, NX7.5.5, NX8.0.0 -> NX8.0.3
NX8.5.0 -> NX8.5.3, NX9.0.0 -> NX9.0.3, NX10 Beta

 

[bdurack]

This worked a treat!! Have exactly what I was looking for now, thank you so much! Have definitely learnt something new that will prove useful time and time again. My only issue is that now I have the shape I want but it has no thickness. How do I add a thickness to the created model of say 1.5mm?

Thanks again for all the help, always nice to pick up new tricks and techniques

 

[bdurack]

scrap that, I got carried away, it's all there in the video. This video is really great by the way, you should upload it somewhere so that when more people like me struggle with something similar they can find it

 

[bdurack]

I have managed to create two concepts now thanks to your help. Here they are:

 

[bdurack]

and the other:

 

[bdurack]

hi again

I have run into trouble when trying to thicken my spherical sheet I modelled. It says cannot apply thicken, and I don't understand why. I want to thicken the sheet by 0.8mm to create a web within a web effect. Is it failing to thicken because of the complexity?

Any help would be great! I have attached my part file too.

 

[JohnRBaker]

Yes, I would say that your example exceeds the limit of what would be considered as too complex. Of particular concern would be those areas where the sheet body comes down to very long, narrow 'spikes'. Anytime that you have details with that sort of slenderness ratio you're probably going to have problems.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.