How can I create a smooth ergonomic surface?

JeH

Hi! I’d like to create a nice ergonomic surface to this case, which has two batteries sticking out on it’s back, that I added.
I tried boundary surface, surface blend and fill but was not able to get anywhere near a satisfactory result. The only thing I can get to show up at all is a detached face blend, that is far from useful. 

The pink surfaces should be added rather than produce new ‘objects’ and of course both batteries should be fully enclosed. A smooth transition into the case edges would be nice. 

Can you explain how this would be realised?

Here is my model: https://cad.onshape.com/documents/a924765c7bd63f6713c7a208/w/5d66717cdfa3dce030d5f493/e/a75b413d6c58529556799f4b

martin_kopplow

To achieve this, you'll need to learn surface modeling. That's an art form some people make a living on and is not explained in a few words. There are quite good surface modeling tutorials in the leaning section of Onshape, though, which I recommend working through.

To build the surface you want, you'll have to create sets of strategically placed curves, to define the shape, such as a representation of the base part silhouette, the contact faces, and some profile and guide curves, then put a number of faces on them.

S1mon

It also looks like you're starting with an imported STL or other mesh. While it's possible to work with these in a mixed modeling approach, it will only make surface modeling - which is already not a beginner thing - much, much harder. I would recommend learning to remodel the basic imported shape natively first, and then work towards how to add whatever shape you want for the battery bulges.

John_P_Desilets

@JeH  100% agree that surfacing is the way to go here. One technique you can try out is offsetting some of these surfaces to use as construction geometry and add the features to those surfaces. Once complete, you can enclose the surface and add to the import. Not very "clean" so to speak, but opens the door to alternative workflows. 





Here is a quick example of using this workflow with an STL. 


 




Both examples are in this document. 

https://cad.onshape.com/documents/f9677ffc3b05bc175eefda07/w/d7527c0554d0ad3dc610062a/e/fd85329677806a482d6613b8

martin_kopplow

To achieve this, you'll need to learn surface modeling. That's an art form some people make a living on and is not explained in a few words. There are quite good surface modeling tutorials in the leaning section of Onshape, though, which I recommend working through.

To build the surface you want, you'll have to create sets of strategically placed curves, to define the shape, such as a representation of the base part silhouette, the contact faces, and some profile and guide curves, then put a number of faces on them.

S1mon

It also looks like you're starting with an imported STL or other mesh. While it's possible to work with these in a mixed modeling approach, it will only make surface modeling - which is already not a beginner thing - much, much harder. I would recommend learning to remodel the basic imported shape natively first, and then work towards how to add whatever shape you want for the battery bulges.

JeH

Ok, thanks for your responses. What both of you say matches my experience. I guess I hoped for some kind of magic wand feature I somehow missed 😂
I’m doing basics modelling for the home-3D printer for some years now but surface modelling is at totally more complex thing. I accept that

The original file was imported as step converted from stl, thats right. Basic changes to the body work absolutely fine this way. But I realise that complex features require calculations that are near to impossible with the amount of datapoints in a body converted from mesh. 

I will try and learn to get the battery bulges the way I imagine in a fresh and simplified model. If that works, a manual remodelling of the imported shape seems to be unavoidable

John_P_Desilets

@JeH  100% agree that surfacing is the way to go here. One technique you can try out is offsetting some of these surfaces to use as construction geometry and add the features to those surfaces. Once complete, you can enclose the surface and add to the import. Not very "clean" so to speak, but opens the door to alternative workflows. 





Here is a quick example of using this workflow with an STL. 


 




Both examples are in this document. 

https://cad.onshape.com/documents/f9677ffc3b05bc175eefda07/w/d7527c0554d0ad3dc610062a/e/fd85329677806a482d6613b8

JeH

Thanks, that’s a good point! I already realised that a lot of tools, that do not work with imported bodies to begin with, do suddenly work as soon as a part of the body gets extruded on to or removed.
Offsetting the face and work with the result sounds interesting, I will try that. 

Meanwhile I somewhat understand the boundary surface tool and composit curves a bit better and came up with this almost acceptable result. Even though I still miss some good ideas to fill the underneath of the new surface and combine all into one part