How do I create a round hole in subD?

I become familiar with subD in Rhino in recent days and began finding out its commands and doing exercises for creating an object. I finally created this vacuum cleaner. I tried to make a hole in front of it. I used projection ( of course I used circle earlier) but when I want to delete the faces inside the polygon the complete faces are selected that are out of the polygon and creating a hole is not possible.

My question is this, why the project doesn’t separate the faces here? How I can create a hole in subD?

Thank you

I’d start by rotating your projected circle 90 degrees. remove the three faces in the front that the circle overlaps. Then select edges on both the circle and the vacuum cleaner body and bridge the gap.



subd_test.3dm (206.0 KB)
Please consider also the way where you prepare the second mesh (the hole cutter) and you will freeze subd and have ordinary high poly mesh to cut a hole with booleans there.

The next way is to convert subd to NURBS and cut a hole also with booleans or other Rhino NURBS tools (f.e. MakeHole).

If you want pure subd hole then you should change topology to not have pinch there and have mostly quads (sometimes triangles, without n-gons).

Every hard corner should have at least two close edges

Maybe the bottom of the hole is not elegant but on a flat surface, you won`t notice.

a more important question, do you NEED the hole to be subd or can that be added later after converting to Nurbs?

I encourage you to use the best tool for the job… subd makes sub optimal circles, where Nurbs makes great circles. Make sure you are not punding in screws with a hammer when a screwdriver would work wayyy better…


Thank you Marcin, inju and Nathan for your mercy but no one of the methods creates a perfect circle. I had to delete the vacuum and try to examine some method by myself on a simpler shape and eventually I could create a perfect circular hole. I wonder why projection doesn’t work perfectly in subD ( the projected polygon doesn’t situate on the faces properly)?! There is a probability that I couldn’t use project in subD correctly and had to use an innovating method by myself. I give thanks you again and hope you help me in other cases :slight_smile:
I used an octagonal and thus created a perfect circular hole


Hi Kyle

What do the professional users do after creating an object in subD? Do they convert the subD shape into NURBS? Is it necessary to do this conversion? When I convert a subD object (with beautiful and regular wires) into NURBS it takes a shape with messy and different wires that are seen below

Can I convert the NURBS into subD again after I did some operations on the object?

It’s not the right answer for a 3D artist. Pls be aware of the workflow pipeline later on.
What happens if you need to unwrap UV, texturing by another software? Do you mean Subd to Nurbs and then convert to Mesh?

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Of course Rhino’s not largely used in that world, it’s not remotely oriented towards it. It’s still theoretically impossible to cut a precise actual circle in a SUBD or a mesh, no matter what software you’re using, so…what do you expect? Aye cannot violate the laws of mathematics captain! Your options are to make an approximation in SUBD or convert to NURBS. The basic fact you can cut precise curves in NURBS is why they still rule the CAD world.

I agreed with your thought :)).
I just want them to keep improving the SubD workflow in the next version.

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I generally add a SubDCylinder at the location I need to create a circular hole. I remove the cap from one end and circle looks rather good, then use the bridging method. That said, I have used this mostly on planar areas, not on non-planar areas as yours. I’d probably make the hole in a planar version of your surface, then afterwards edit it so it follows the original surface, then replace the original with the new one with hole in.

For visualization and form-finding purposes it should be more than enough.

Most likely people know or will find much better ways.

the nature of SubD does not imply a perfect circle

For form finding I would recommend setting something up with grasshopper for an “auto-boolean”. Leave your subd alone and enjoy the good topology and do the hole subtraction in Nurbs. Best of both worlds and working “non-destructively”.

How do you imprinted the hexagonal on the shape, using project? Why when I use project in subD it doesn’t situate on the faces and some of its edges go behind and don’t appear on the front view?

I see an option in project named " Cplane Z" I tried to change it into " Cplane X or Y" but didn’t find its approach. How can I do that?

I applied a circle using the Align command, then the EditPtOn command, and pulled the corner points of the cutout on the circle using the Align command.
Аnd the hexagon was only because of your topologies.

I don’t know these types of conversations. I am working with Rhino for about one year and have always worked with NURBS. I neither worked with mesh nor subD. Now I need to work in these two workshops but don’t know accurately which one is the final destination of the professional 3D designers after completing a design, NURBS, mesh, or subD?

Do they go back to NURBS always for getting the final output file?

it’s envy for what purpose you need the output file.


When I use selvloumpipe and select rectangle; the circle is selected and none of the edges turns into yellow. In this condition when I use Align an irregular shape is created



I followed all your guidance step by step but I don’t know why whatever I try the part turns into this shape. I don’t know what is wrong.