Need help creating a manifold surface with 5 holes.

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Permalink Reply by Dave Anderson on October 31, 2012 at 4:07am

Rhino is terrible for these kind of things. And T-Splines changes your tubes as you mentioned.

I'm afraid what I'll attach is something you may have gone through already from what it sounds like, but have a look still.

I first flipped one of the tubes which was inside out. Then I rebuilt the tubes with a tolerance of 0.05 (didn't try to optimise though) because especially the two smaller tubes had a much too high point count for these kind of operations. This breaks your geometry down the other end but I'm positive you can get around that by just reconstructing the end part using a loft. I then extended all tubes with extendsrf to intersect and trimmed them to a closed polysurface. The two big ones are relatively happy to use filletedge. They create awful polysurfaces, but if the transition radius is large enough for you this might just be a quick way of getting it done. You can also remove the fillet surfaces, merge edges on the tubes, and use blendsrf for G2 contiunity (this itself will need a lot of tweaking and back and forth though).

The two smaller tubes are a lot of work because they are so close together that with a decently large transition radius they will first have to transition into each other and then into the big centre tube. But since you have no curvature information for the "second" transition when you blend them together, this is pretty much impossible to do well from my level of knowledge.

Brian James did a very quick tutorial on this a couple of years ago: http://tips.rhino3d.com/2009/02/modeling-y-branch-polysurface.html

It's just a trim+blendsrf, which in your case might be a starting point. You would probably need a construction plane for the two tubes to do this well.

I think before you go at this you may want to invest more time into getting more out of T-Splines, as it's usually intended for these kind of problems. I have a similar problem with it though in that it changes my "source surfaces" too much when I do T-Splines operations.

Good luck anyway.

Attachments:

• problem.3dm, 3.8 MB

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Permalink Reply by Jesse Charles on November 1, 2012 at 7:06am

Interesting techniques! Thanks for the info! I'll see what I can do with it. 

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Permalink Reply by Brian Allaop on November 5, 2012 at 4:59pm

jesse,

 

I have attached a .3dm file with the arms blended to the main shaft area. Not sure if this is what you were expecting but i did it with some simple teqniques that i have developed over the years. Let me know if this is what you wanted and i can discuss the method further after that.

 

Regards, Brian.

Attachments:

• problem-blended-BGA.3dm, 3.8 MB

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Permalink Reply by Henri on November 9, 2012 at 3:24am

Hi Jesse!

I think best way to do this is to use "Variable radius surface fillet"-command.

You have to extend all the pipes first by using Extend tool and use (Type=Line).

Then use normal cut tool to cut extended pipes. Cut also Biggest pipe so that there is holes for the smaller pipes.

Then use Variable radius surface fillet tool to give nice fillets for the edges. There you can choose what kind of fillets do you want. Between 2 small pipes you have to add new handle from the fillet settings. Add handles between pipes and give radius about 0.03, then fillets does not hit each other.

I hope this helps you to solve the problem.

Henri

Attachments:

• problemHenri.3dm, 4.9 MB

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