Hey guys, I was wondering if someone could help me out. I am wanting to smooth the connection points of a NURB that I modelled. I have been trying many different things, including Sub-d’s, but not with much success… especially keeping the geometry of the 3 connecting pipes the same. Honestly, I thought it would have been a pretty straightforward task as it is in Blender. Appreciate your help!! 
In NURBS surface modelling, you can use fillet surfaces or blend surfaces for various kinds of surface transitions. Below, for example, is a G1 chordal fillet.
Thanks for the quick response! Unfortunatly I think this is the easy way out. In my case I have the two thinner pipes quite close to each other and therefore the fillet could only be tiny. Ideally they somehow merge into one fillet. I am uploading the model for you to have a look if you have a second. Thanks once again
Filleting Model.3dm (203.9 KB)
You can fillet like so. Without a sketch or mock-up photo, it’s hard to know what you really want, as there are many possibilities how to go about it, which all look different, and would be modelled differently.
blender is definitely mesh based, that is a different paradigm altogether compared to nurbs. so the comparison is pretty irrelevant. with mesh you can do all sorts of complex “surface” manipulation much easier, if the diameter will stay accurate is a different question. besides not having what nurbs inherently are actually for. maybe you dont need nurbs then?
for this part its quite a fiddle since your parts are very split, so i rebuilt the bigger pipe by duplicating the lower edge joining simplifying then extruding and trimming all the stuff off again.
then i used blend edge for both sides after which i exploded and trimmed the centre offset from the centre with 2 lines then blended the 2 blends together. you are of course limited to the dimension the distance to the centre hole allows. you might get around by using a variable fillet. but i leave that to you.
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Considering how it’s literally mathematically impossible for the SubD to actually be round, errr not really.
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