Hi People hope everyone is good and having a good day, i am trying cut out a quater of a circle and i have tried using the knife tool but found this rather dificult and have tried the default editing tool and tried inverting the excess inwards but this did not work as well, as you can probably tell i ahve only just started learning how to do 3D modelling on blender. Basicly i just want to get rid of the excess quater i do not need. please see the PNG i have attached. Any help would be apreciated. Thank you :) P.S. i have done a landing foot and cut corners out thanks to bruno's instructions :) however i do it manualy for each corners and some corners as you can see from the picture are not equaly continuitive :)is there a way that i can duplicate the first cut like for like so all corners are the same :)enter image description here

SimonScreen shot of blender project i need to cut

  • $\begingroup$ maybe you wish to remove a quarter of the sphere-like big mesh as outlined in the picture? have you tried to select all the inner vertices and (eg) delete them? later you'll need to fill the hole though... $\endgroup$
    – m.ardito
    Feb 1, 2018 at 12:47
  • 1
    $\begingroup$ If you need to add more or different pictures edit your own question using the edit link, not someone elses answer. $\endgroup$ Feb 4, 2018 at 14:08

2 Answers 2


Sometimes it can save time to build the new geometry you need.

enter image description here

In this case:

  1. Add a new UV sphere aligned to the world axes, with twice as many segments as rings. (Here, 32 and 16)
  2. Delete the exterior faces over the section to be removed.
  3. Put your snap settings to vertex, active, snap to self.
  4. Extrude the vertex at the north pole downwards, constraining to Z, (E,Z) and snapping to a convenient vertex on the equator. This will create the edge from the north pole to the centre of the sphere.
  5. Set 'Automatically merge vertices' on, and extrude the new central vertex outwards twice, once to each of the bottom corners of the removed section of the sphere. This will create the other two straight edges you can see.
  6. Select all the new straight edges, and from the (ctrl-E) edges menu, select subdivide. At the bottom of the Tools panel, set the number of cuts to 3.
  7. Fer each new flat face you are going to create, select the edges surrounding it, go to the face menu (ctrl-F) and select 'Grid Fill'. At the bottom of the tools panel, set the span to 4.
  8. Bevel the edges of your new faces, if you want to.

It may all seem like a bit of a faff, but once you can find your way around, this sort of approach can take less time than tidying up after a Boolean. (I'm sure someone here will point out how I could have saved a few steps.)


how about boolean modifier?

  1. select your sphere
  2. create and place a cube to remove part of the sphere
  3. add the boolean/Difference modifier to the sphere and select the cube as the object to use for the operation
  4. apply

enter image description here

  • $\begingroup$ Hiya Bruno thank you for your reply i am sure it is something i am doing wrong but i did follow your instructions and whne i clicked apply it cam,e up with the error message 'moddifier has been disabled'. Also i am trying to do slight indentations do you have any instructions ont hat to please? $\endgroup$
    – user51790
    Feb 3, 2018 at 19:14
  • $\begingroup$ Hi Bruno sorry about that it was me i missed out the part to switch it to cube in the object part. thank you. Would you be able to let me know about the indenting bit please. $\endgroup$
    – user51790
    Feb 3, 2018 at 19:26
  • $\begingroup$ :( ok i have tried the boolean on a different part of the model that i want the same effect on except with a sphere this time, however i still gt the error message that thge modifier is disabled again even though i do exactly how i did it before. :( can you offer any advise on what i am doing wrong? adding the sphere object dont seem to work. $\endgroup$
    – user51790
    Feb 3, 2018 at 19:56
  • $\begingroup$ Ok it lstarted to let me add the object the right one as i had sphere 1 to 9 listed however i still have an issue i click apply and it dont come up with the error message there is no spherical incut performed one i have taken the sphere out :( again i am new so i am sure it is me. :( $\endgroup$
    – user51790
    Feb 3, 2018 at 21:04
  • $\begingroup$ Are you using other modifiers like "Array" etc? If so, you have to apply them before doing the boolean otherwise the boolean op may not have a real mesh to work with... $\endgroup$
    – Bruno
    Feb 4, 2018 at 9:05

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