Hi everyone,
I’m beginer to Rhino and currently practicing the Trim command in both Rhino 5 and Rhino 7.
I have a curve that I want to use to cut and remove the upper part of a surface, but it doesn’t work.
I still don’t understand the reason why it’s not trimming.
I’ve uploaded a screenshot and the .3dm file — I would really appreciate it if someone could take a look and help me out.
Thank you very much!
QA1.3dm (239.6 KB)
What you have there is a polysurface - two surfaces joined together - and it appears it is the result of the surface being split at the curve already. If you explode the polysurface you will see that the upper and lower parts separate at the trimming curve. You can delete the upper part.
Perhaps you can explain how you made the object in the first place?
I created the surface using the Sweep 1 command, and it’s a single unjoined surface.
However, I still can’t figure out why I’m unable to trim it.
Any help would be greatly appreciated!
But i create to curve and don’t Explode. Could you please help me figure out how to fix this?
I honestly don’t understand why it’s happening. 
Why it is happening is that the trimming curve falls right on the intersection between the two surfaces. Rhino doesn’t like it when that happens.
Thanks to Helvetosaur, I somehow managed to trim it by luck :D. I still don’t understand why it worked.
Just like @Helvetosaur says. If you explode your surface, it’s already two surfaces. No trimming needed. See below.
Thanks @Helvetosaur and @Lagom. ^^
Sorry if these questions are silly but I am new so there are many errors I can’t understand.
I understand it now.
great.
can you please mark one of the answers above as solution.
so others don t need to read through the topic to see it is solved ?
there is a solution checkmark (for you as topic creator) under each post.
and to add what was said above:
an alternative to _explode would be to _extractSrf with copy=No
happy modelling and learning - kind regards -tom
Thanks Tom_P ^^
