Blend puzzle

This is really a general Rhino problem, but I’ll post it here since I’m using the WIP.

In the attached file I’m trying to blend the seat surfaces to the flat top. As you can see I piped their intersection and trimmed back. I seem to be having the problem with the back round edge of the seat, for some reason it won’t select when I try to chain the edges for BlendSurface. Same with Sweep2. I can make 3 separate sweep surfaces (side, back, side),but they don’t have continuity.
What am I doing wrong?

blend.3dm (424.5 KB)

Hi Nick- it seems OK here -

Does that not work? The edge chaining workflow has changed some from V5.


Hmmmm. It works fine with Autochain but not with “manual” ChainEdges. Is that typical?

Ah yes, I see - yeah, if you want to chain edges, either automatically or pick by pick, you now need to set that option at the first prompt. I know this is a little jarring at first, and right now I do not recall what problem it solved - but there is/was a bunch of churn about it at one time (here) and that is what fell out as a first shot.

(I also see that hand chaining may be tricky in this case because there is a very tiny edge on the inner set that you’d probably miss if picking by hand.)


Thanks Pascal. Now I have another situation on the same model that doesn’t seem to work.
FilletEdge and blendEdge fail at .2 units on the top perimeter edge of the attached model. I thought that might be too small for some of the short top surfaces but 0.18 fails too. Do I have to trim back and manually fillet the surfaces?

filletedge.3dm (211.9 KB)

I see that - it is a good case for Chuck to have a look at , I’ll put it on his pile - as far as I can see so far, the problem occurs at the one corner that overshoots because (I think) the intersection needed to trim back the fillets crosses two separate fillet surfaces from the overall solution on the front.

Hand trimming, I guess…

(251.5 KB)


I had thought that my fillet would avoid crossing into the second surface, but looking at it now I realize the vertical angle of the side is causing the fillet to go deeper than I expected.
Thanks for your help!

This might be another thing for the pile. Later version of the same general model, trying to fillet edge the top to the sides. Chain fails between the two seats. It’s a closed polysurface and I’ve tried a variety of radii.
fillet puzzle.3dm (455.3 KB)