Trimming question


I have old borders after DupBorder and surface left after UntrimBorder. I`ve changed trimming curves a bit and now I would like to trim it again (I know replaceEdge command). I would like to trim like on GIF but with one click. Trim a surface to a closed curve as one goes without clicking surface after surface. Is that possible? This question is a bit deeper cause in real life after Untrim I have small pieces of surfaces which I have to find and click after triggering Trim command. Sometimes they are very tiny and hard to find.

Choosing a closed border and selecting a surface which should be trimmed to the closed border would be easier and faster for me. Is there any command for that?

Thanks in advance :slight_smile: and sorry for a noob question again :wink:

Edit: for now when I have a tiny surface over the border to trim I ExtendSrf to have a better click but it’s not a good solution because I`m changing the curvature of the surface.

You just need to increase the size of the surface so that it is larger than the curve. For example, using the _ExtendSrf command. Then you can trim the surface in one click and more cleanly.


An alternative to Trim is to Split and then Delete the unwanted parts.
Invert will invert the selection - select the unselected parts and de-select the selected parts.
So you could Split, select the part(s) to be kept, Invert and Delete.

SelSmall will select objects smaller than a specified size.
Split, SelSmall to select the unwanted small parts, Delete.

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@saw-3000 : Does ExtendSrf change a surface shape a little during use?

This is exactly how I`m doing it right now but…

I`m not sure but in some cases, after extending and trimming again some other edges were bad than before.

I like this. Thanks.

I guess not. Below is an example with isocurves.

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OK. In your case, isocurves are standing at the position. I`m on windows Rhino v7 and I had a few cases that isocurves moved during extending. I will try to record it later. That’s why I’ve thought it is changing during extending.

Edit: Now I’m trying and they are standing as in your case. I’m not sure maybe I was wrong and they are standing all the time. I will watch this during work. Maybe you are right and I`m wrong.

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you can also explode the curves and used EdgeSrf and avoid the trimming altogether.

…and trim surface to surface? Sorry, I don’t follow.

just use the new surface. it should be congruent with the old i believe, since the curvature, tangencies will be determined by the input curves as long as its not a doubly curved surface.

question also is, why did you untrim just to use the initial surface again, why not not deleting them? or is that just a one time It happened thing?

I could do a Patch on borders and choose that new surface (EdgeSrf) as starting surface. It should have the same borders and a similar shape then.

The answer is: I don’t know. I`ve thought it would be better not to change surfaces after offsetting it to be sure that I have the exact thickness there.

The results using EdgeCrv may not match the original surface, depending on the shape of the original surface and the shape of the edges. Use PointDeviation to see if it is close enough.

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yes but in this case it might, on a doubly curved surface definitely not

That`s why I’ve thought to use Patch with starting surface to pull that new surface to the old one with having the same borders.

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Please try
rhinopython/ at master · CADacombs/rhinopython · GitHub
The 6 .py files include support modules.

For trimming:

  1. Run
  2. Hit Enter so that curves and/or naked edges are automatically discovered.
  3. Click the surface in an area to keep.

For splitting, do the same with


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Super but it doesn`t work for me (yet). I have an error after triggering the command (nothing selected).
Maybe I should have some additional library?

Edit: It’s working!!! I’ve downloaded from your site (link). I`ve copied that file to the rest of the files. All is working properly now.

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It`s brilliant!!!

It`s now two clicks instead of a few minutes of clicking when you have small tiny surfaces. Extending surfaces also takes some time.

Now it`s needed only to isolate problematic surface. DupBorder to have curves. Untrim Border and after it use your amazing script.

It`s a very big PROS that script allows change tolerance during triggering so there is no need to change that in preferences. Using better tolerance during trimming should make joining easier. Nice :slight_smile:

Amazing, Steve!! It`s so good that should be sold.

McNeel should make this script by default IMO.

Click. Click. Done.

Edit: I`ve created button for that in MMB popup :slight_smile: LMB to trim RMB to split :slight_smile:
In 30 seconds I created even icon for that

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For anyone else who will download it, I just added the missing file to the .zip.

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