Each time I think I've got a perfect shape to throw at the Network tool, I'm quickly humbled. I don't think I've ever truly gotten the hang of this tool. I'm attaching a group of curves that I'd like to network, but I'm having no luck. Is there any way to network this frame? My questions about this command always seem to be along the lines of:

How many curves do I need? Do I have too many, too few?
Should my perimeter curves be closed or segmented?
Should be internal curves be lying on top of each other or segmented where they meet?

I've tried multiple approaches on this shape, but I get a calculation failure each and every time.

Hi Brandroid, if you look very closely at your middle curve, it's subtle but it's a little darker than the others:




Then if you select it and look at the object type indicator, it says it's a "Closed crv":




So that means that curve is doubling back over top of itself, that's why the Network won't work with it, all the curves for one direction in a network should be either all open or all closed.

That middle curve will need to be fixed up to not be self overlapping for Network to have a chance. I'm not sure that you're going to get a good result any though because you've got a very tight bend just in one spot there, I guess it looks like you're hoping these spots will match up with each other:




But what's probably more likely to happen is spots like these will be actually matching with each other, since those tightly bent areas are at fairly different distances along each curve:




It generally isn't good to have such tight bends in a single network, it would probably be more controllable to build that in separate pieces, with one piece matching to each broad slightly curved sheet and having tight bends formed by fillets or blends between those pieces.

Hope that helps.

- Michael

Hello,

Once you get that center curve straightened out so it isn't closing in on itself you don't need to change anything else to get this networked result, although you will be left with an uncontrollable surface as Michael was indicating.

Hi Brandroid, I've atttached a version with the middle curve cleaned up so you should get a Network result with it.

But it's not going to be a great result because there's too much variation between the curves, things like very tight bends are not good to do in a single network.

I probably wouldn't try to use Network at all to do something like this, I'll see if I can put together some other steps.

- Michael

Hi Brandroid, so instead of trying to do a Network all at once, I'd probably start with sharp corners instead of putting the tight bend in right away, and starting by doing a loft like this:





Then select these edges and curves and run Construct > Planar:



Now you've got 3 surfaces built, select them and use Edit > Join to glue them together, and then select the whole object and run Construct > Fillet to round off the sharp edges.


Also another different way which actually gives the cleanest surfaces is to extrude from your centerline like this (using "Both sides" option in Extrude):





And then in this version, the "side curves" are 2D planar curves that I flattened. Instead of trying to surface those, with this method you'll instead use them as cutting curves in the Edit > Trim command, you can actually select all 4 curves, those 2 planar Top-View ones, and the rounded end caps as the cutting objects for Trim, then they will cut the simple extrusion and you can select these areas to discard:




Usually if something has a well defined 2D silhouette it's good to build an initially extended simple base piece and then cut it with the 2D silhoeutte and let the final 3D curve be formed by that intersection calculation rather than trying to draw the 3D curve in to start with like you were doing.


- Michael

<< Usually if something has a well defined 2D silhouette it's good to build an initially extended simple base piece and then cut it with the 2D silhoeutte and let the final 3D curve be formed by that intersection calculation rather than trying to draw the 3D curve in to start with!

Tao of the Nurbs! ;)

Michael, thanks so much for that explanation! Not only do I have a better understanding of the network tool (and my foolish mistake), but I learned a better way to achieve my end result. I'm always impressed with the level of help I find in these forums!

After rebuilding my surface using your suggestions, I was able to blend it with my main surface creating the filleted edge i was looking for. The sync points feature is awesome! Thanks again so much!

Cheers,
Branden