How to draw around surfaces and how to make it perfect?


I am trying to make a shape look the same in both sides (I made it by lofting semi-circles) but the only way I know to do this only by moving this control points but it seems not able to deliver a good enough result. I want to bend this shape like the blue line.

The other question is about drawing around surfaces.

Hi Leonardo - it’s always best to send the objects you are asking about as a Rhino file when possible. I am not sure if I understand the second question, but perhaps the Project command is what you are looking for, maybe with History.


3D TULIO 11.3dm (4.8 MB)

Hey pascal, here is the file.

the second question I am trying to put some addons on those curves by the outside, somthing like arraying it.

sorry for bad english, not mother language

Leonardo, can you please post just the curves and the resulting surface that you do not like? I am not sure what I am looking for in the file you sent.

You may need OffsetCrvOnSrf for the second question, but I am still not sure if I get it
@giuseppe , can you take a look?



3d tulio only part.3dm (409.7 KB)

sorry, here it is pascal.

Are you looking for something like this ?

Better image …

Hi Leonardo - what curves generated this surface? I’d like to reproduce your process to see if I can make a suggestion for making it better - is this the set of curves you are working with?:


yes, how did you done this?

i done the curves with arc tools + polylines based on a contour I done from another polylines combination… don’t have it anymore, sorry

i am sorry to disturb you, but maybe my reply wasn’t notificated and i really need to know how to do this, so i am leaving another reply :grin:

Caio @Leonardo_G_Pate ,

first I made 2 lines across the top and bottom opening in your original shape.

use arc, start, end point on arc to make side arcs

extract isocurve from your “red” shape (you may have to change U or V direction) at point where arc touches.

add a point to top and bottom line where arcs meet.

Sweep 2 rails, choose arcs, then for cross-section curves pick, point - then middle curve, then other point.

I hope that helps,

A presto, Randy

nice! thanks a lot mate!



in the last step is only building the upperside of the shape (upper from the cross-section.

how yours was able to be a whole unit?

I just mirror the top with the bottom line I used. Then mirror again left to right.

Does that make sense? Just leaving for a few hours, I can do some screen shots later if you don’t get it.

Good luck

alright, could you send me the screen shots?? thanks man, i really cannot visualise without it

Ok, a few more minutes here, mirror

Then move new one from top point to bottom.

Does this help?

Ohh, it wasn’t this what i was meaning… it was this:

i want to know how could you get the total shape of it.

Sweep 2 rails,

point at top,

then exrtracted isocurve at the mid point,

then the point at the bottom.

Shown in a image above.