Newbie question - Deleting curves after creating polysurface?


I am new to Rhino and drawing software in general. So this might be a bit of a dumb question.

I have started building simple models and use a lot of polycurves and then extrude surfaces to make the 3d part.

I tend to work like a Lego kit and then build parts of model in isolation and then bring them together.

Now when I move a polysurface it leaves behind the original polyline. Is there any advantage of grouping the surfaces and lines together and moving them as one “component” or can I just delete the original line as there is no need for it anymore?

Thanks for your help.

There is no real problem in deleting them - I have a tendency to keep my construction curves “just in case”, but everyone works differently.

It’s not necessary to group the curves with the objects created from them; I suggest if you want to keep the curves that you move them together with the surface objects so they stay geographically referenced, and perhaps create a “construction” layer to throw the curves on so that you can hide them (by turning the layer off)…


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Dear markml,

Welcome to the community. If you’re sure you won’t need the curves, then definitely delete them, but it is always a good idea to keep them, as Mitch said, on a separate layer, just in case you do.

If you do delete your curves and find out later that you need them, you can always generate new ones with tools like dupedge, dupborder, etc but good to just hold on to them.

Experience will tell: )


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Do not delete curves. Put them on a separate layer.


  • They do not take any extra space (compared to your surfaces.)
  • You may change your mind
  • Your client may change their mind
  • You may need one of pieces or parts for another project

If you do need to make a change later (how do you know you NEVER will?) then it will take many times longer to recreate and re-draw all of those curves compared to just saving them.

I would add that you should come up with an easy to use and access system of keeping your reference geometry for future use.
If you put all your curves in a “curves” layer, it will be arduous to find the good one after several iterations and a few months later.
I create a sub-layer under “reference curves” for each design session but you could go with one per day or one per hour or one per “exploration phase”

I agree with Schultze and others to not delete ‘design’ curves and yes put them in another layer.
In my training I always tell that input curves for surfaces are the DNA of your design. As control points of curves are the DNA of the curves.
This is especially important with nice and fair freeform curves that contain only a few control points. It is often impossible to reconstruct these from surfaces. Then you end up with curves that contain many control points which makes them useless to edit easily.
For example the centre line of a smooth railing pipe. Always keep these curves.

Or a sub layer (or several) per principal object - with the finished object on the parent layer… many ways to go… --Mitch

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Here’s another way to answer this question. If you were sketching, would you throw out every sketch except the very latest? All the designers I know keep them in a sketchbook or file folder. Curves should be treated the same.

i delete them when i know that i can recreate them with dup edge or dup border which fits my work 95% of the time