Bug: Blend SRF does not make solid where it should (3 bugs in one quick report actually)

I love having this new tools BlendEdge, and I really appreciate that in this case even if it failed it gave me all the complex output needed to then duplicate borders and retrim an unblended version of this model to make a complete blended solid.

Non let’s look at this rookie tool in action:

and let’s comment on all the things that went wrong here:

Bug 1: Blend did not give me a solid when it should have.

Bug 2: I input the number 2. as in 2mm, not the number 2.0000 as in 2.0000mm, why on earth is Rhino showing a preview with the number 2.0000 39 times? that’s 5X (6X if you count the period) the number of visual information I need to make a good decision. Let’s all make good decisions together!

Bug 3: Rhino also decided to change colors of one of my trimmed input surface to a layer default color, for no reason (see the green bottom is now gray)

Hi @chuck, file is here for forensic discovery
2mm_blend_fails_gf_201101.3dm (276.3 KB)




I’m on it. RH-61248 BlendEdge loses face

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thanks Chuck, this is for very important work as you can see here. Play this video with sound at your own risk, my significant other is learning violin :grimacing: :hear_no_evil:


Oh No! I’ll get to it right away.

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Shouldn’t the Result of BlendEdge be like this?

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Don’t know if this is of any help, but I get this all the time in version 6 too.
The surface usually is properly gone altogether, not one of theses strange cases were a corrupted border makes a surface invisible and untim-retrim can solve the problem.

As a workaround this is solvable by extract-copying the surface before blending and then using the duplicated border curves to trim the extracted surface)

I wasn’t reading propperly. I do get the same result as @gustojunk with a grey bottom part but the decimals are still set in Options, Units, Model, Distance Display…

I also get a closed Brep with 2mm FilletEdge, but not a closed Brep with BlendEdge, even though all those blends do work well (just don’t look to too closely at them with Zebra or anything too academic). A bit of manual trimming work does get you a closed Brep too. So I think Chuck is close to the trophy here

I get the display precision thing. I do want that close to my tolerances for things like CageEdit. But if I type “2” (as compared to “2.0000”) in a running command, I think I should be able to see “2” everywhere during that command.

Yeah it’s quick to solve, as you can see in my video, the part is done, printed and had a few coffees with it already, I just want to give Chuck something to do :slight_smile:


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I meant BoxEdit. I’m so sorry for using ‘CageEdit’ and ‘tolerances’ in the same sentence.


Yeah, I watched the video right after my response🤷🏼‍♂️

@gustojunk Finally got it. The problem comes from a false assumption in the setback code when any of the surfaces are not NURBS. The fix is pretty substantial so won’t be out until V7 SR2. If you change all surfaces to NURBS, it works now. You can do this with the ToNURBS command. Currently, this will give you a bad object, but the blend works and the badness goes away. I’ve also fixed ToNURBS so result won’t be bad in the future.