How to use the Clip Curve Brush for radial symmetry

Hi there,

trying to get rid of an untrimmed part of a backcontour boolean.
I would usually work on the boolean subtool to make it superclean.

But to get a bit more flexible and because I run always again and again in this sort of problem,
it would be one for all time, good to know, how to solve the problem with a simple brush solution. Even if that will not be as clean as, working with the zmodeler tool, or similar topology tools.

That is the modeling situation:
(for better understanding - the front face)

5 identical pieces to get rid of.
So I will need to use radial symmetry 5 times.

I select the relevant part to separate it from the rest.

Idea is, to use the clip curve, or knife curve to cut away this overhanging noses.

But I suppose the clip curve brush issn´t the right tool.
It results in some fancy forms.
The planar tool would work, if the base surface wouldn´t be a ring.
So can´t fix it with that either.

What would be the tool (brush) to go to do it manually?
Thanks a lot for your help!

Hello @DarkStar ,

This is a tough one. I’m going to assume that you don’t have viable low poly topology with clean polygroups to edit the topology directly? If you require this kind of control over complicated forms like this you may want to consider working at low poly. It would be a much easier task to do this if you had deliberate topology to edit with ZModeler.

Clip Curve won’t work in this case because the effects of the stroke are aimed inward and will affect geometry on the other side of the model. I doubt you could achieve very clean results doing this in any case.

LIve Boolean would be your safest bet. That will let you draw out cutting meshes and adjust them all simultaneously with radial sym.

As far as a brush based approach there aren’t many freehand approaches that will work here. The contour of the geometry in that location is too complicated and it would be difficult to eliminate that extrusion without destroying the surrounding surface.

However I do have one unorthodox idea. It requires that your mesh be perfectly radial symmetrical and centered, with the pivot at the exact center. However, in theory:

I notice that the negative spaces in between the spokes contain exactly the clean contour you’re after minus that raised section you want to eliminate. You could theoretically duplicate your model as a separate subtool, then rotate the duplicate so that those “clean” sections of the rim are now located underneath the sections of geometry you want to eliminate.

You could then carefully mask all but the area you want to affect on the original subtool so you don’t accidentally affect the “spokes”, then use the ZProject brush over the raised sections. It will pick up the surface from the underlying subtool and flatten that section down to the surface of the duplicate subtool. You could also theoretically use the Project All function in the subtool palette to do the same thing. Protecting areas you don’t want to be affected with masking is crucial though.

Tip: one way to get polygroups with nice clean edges on a high res model with suboptimal topology is to carefully paint a mask on that section, then use the Polygroups> Group Masked with a high smoothing value. It will smooth and tighten the edge of the polygroup to be cleaner than it otherwise would.

Hopefully that gives you some ideas on how to proceed.



I was curious about this problem so I played around with a mock case. At first I thought of masking everything except the regions to be clipped and then using Clip Circle brush holding ALT (no need for radial symmetry). Works fine if the underlying surface is cylindrical. However looking closer, the underlying surface of your model is closer to a section of a cone.

So a working alternative that will preserve the underlying conical face and circular symmetry is to duplicate the model, rotate the duplicate so the clear areas on other side of the spokes are in line with the spokes, set a History mark, and then return to the original model and brush away the offending area with the History Recall brush. Can’t use symmetry with this brush so you’d have to brush each area individually. However it’s pretty quick and clean so it’s won’t take much time.


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Hey @Spyndel,

thanks for your detailed solution recommandation.
I worked it out step by step.
Have a look:


That worked pretty good and I learned another tool (Zproject).
Only downdraw is that the radial symmetry seems not to effect the process.

Anyhow, that is a good way to solve this kind of issues,
I run into.

Thanks a lot for your expertice!!!

Hey @tobor8man,

thank you for your ideas as well.
That is very inspiring to hear from you.

You are right, unfortunatelly the rim is in this spot not just round (orthographicly), more a conical formed ring. But thanks for the idea with the centered Clip Circle brush - I bet I will use it for something else in future.

Also the history recall brush I did not know before.
I checked it and I test it like before @Spyndel suggestions.
It worked pretty much the same somehow.
I was wondering because I had some issue this time, because of sculpting the outside (backface masking.)
But then I recognized that I forget to mask it this time, when working out your solution.
So it´s also a quite good solution for me.

With the help of both of you my toolcase get´s more and more extended.

Thanks so much!!!