Making holes in lofted surface

I made an elliptically shaped tower from using the shape/ellipse and then Loft commands. I offset the surface to get 0.25" for the wall and then tried to cut holes in the surface using Trim,Cut, and a bunch of other commands and nothing works. I tried make it into a mesh, joined it and other tricks but nothing works. Might be that I made the tower incorrectly from the beginning…Its not a real surface

Hi bip - I’m not sure what you mean, exactly - can you post the object and some curves to trim with?



I made it into a mesh thinking that would help…the ide of the tube was that I could use it to trim and then delete it

tube#2.3dm (3.01 MB)

Can you post the original surfaces?

How much experience do you have with Rhino?

not sure how to answer that but by my standards I am pretty bad. Nevertheless, I got what I needed but still dont understand how it works. I lofted the curves and the holes got cut with an extruded oval as a trimming object.


There are several different ways in Rhino you can make cylindrical hole in a tubular object. The different methods all do essentially the same thing.

Here is a file showing the basic steps. Hole through a tube.3dm (271.8 KB)

Depending in which method you use in Rhino for making the hole you will get to see what is going on or you won’t get to see what is going in but in any case the underlying process in this example will be the same.

The first step is Rhino finds the intersection curves. There are only 3 surfaces involved in the intersection. In my file they are colored red, white and blue. There are four intersection curves shown in black.

In the second step the intersection curves ate used to divide the surfaces into parts. Some of the parts are used for the final result and some are discarded. In my file the black surfaces are the ones discarded. There are only four parts of the original 3 surfaces that are
useful - the rest are all discarded.

The last step is joining the parts that are left to make a closed polysurface.

If you use the Trim command to make a cylindrical hole in a tube, you can select the tube polysurface and the cylinder surface and then you will need to pick on all the parts that get discarded and then join what is left. Its probably easiest to work in wireframe or ghosted viewport so that you can see parts that are behind others.