Big gaps in draft curve! -Zoiks

I am trying to generate a draft curve for a closed solid polysurface. The result is not continuous and has a lot of gaps. How might I go about getting smaller gaps? Stretch goal… how can I get a continuous curve? -Thanks.

I guess by “draft curve” you mean a sweep (1 rail)? Can you post a file with just the rail curve and the profile(s)? Can’t do much with a screenshot.

No, I don’t believe I meant a rail sweep. I didn’t use a rail… each rib (all identical) was twisted a little bit at a time using
(among others) and a lot of Excel.
just ribs.3dm (2.1 MB)

Ah, OK, a Loft then.

The curves are microscopic - measuring approximately 0.01 inches across and your file tolerance is about the same - that simply won’t work correctly. I scaled them up by 1000 just to test, and I got this:

Which looks pretty good, except for the space between the ends, I don’t know what you want to happen there.

Using 347 sections for loft will however result in a pretty “noisy” surface, it might be better to use less to get a smoother surface, but at the expense of perhaps not going through all the sections exactly.

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I do not get a clean/complete draft angle curve even using a scaled up and simplified (pts reduced from 180 or so to 32 per curve, still way too many curves) so there is still something amiss here, it seems to me. Silhouette from Top gets the full curve.
RH-71842 Draft curve is gappy


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OK, funny, I didn’t even realize that is what was wanted (I should have), I almost never use this function…

I do get a good onscreen “visual” green line all around on both sides at the mid curve, but if I have it actually create the curves, yes, there are gaps… No idea why.

I don’t think I am doing silhouette right… I just get a pile of rib shadows on the C-plane. However, I can do a MeshOutline, Extrude straight, and Intersect, which gives me

Kinda sloppy, but at least there are enough points to build a curve through. Then I should be able to sweep the rail with a horizontal line and use it as a cutting object to make a pair of mold half’s.

Dang, I just spotted the file… Thanks for playing with it! …can’t look at it, though. I didn’t realize we’re up to version 8 already. I’m still on 4 most of the time, trying 7 as an evaluation of the DraftAnalysis stuff. Seems like the devs might have good job security for a while. (know it’s not on the short list, but I gotta put in a plug to offer Rhino for Ubuntu.)

Hi Brian -

Here is that file in Rhino 7 format.
I’ve also gone ahead and split that and added “fins” - just in case Rhino 8 also provides better results in these areas…
DraftCurveGappy-RH7.3dm (6.6 MB)