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I need to round the edges of this object.

The bottom edges are going to be rounded in conjunction with another object, so, I guess, this should be left out right now.

I tried using the bevel tool (and a bevel modifier) on an edge (series of Blender edges), but I got the problems you see on the images. When selecting all edges, the bevel doesn't know any limit and isn't applied symmetrically.

When selecting only the edges shown (or only the other ones), I can't proceed with the rest of the bevel, and strange little artifacts appear.

FYI: The top surface is derived from an icosphere.

Bevel tool

Without the subdivision shown above, a stair comes into existence (bad):

Stair

Whole object:

Whole object

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  • $\begingroup$ reading your two question, I think this is hard to help you concretely if we don't know exactly the final shape in its totality. $\endgroup$ – lemon Aug 4 '16 at 12:48
  • $\begingroup$ I'm modeling a MIDI keyboard key. I already created many objects with the correct measurements and aligned them properly. A non-angular top surface and rounded edges were my remaining main problems to my understanding. Any better idea for an agenda? $\endgroup$ – t_w Aug 5 '16 at 1:45
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Unfortunately I believe you have started on the wrong foot.

You object has a very bad topology, it's not quad based, it is full of triangles. very unevenly subdivided with extremely high density on top contrasting with huge ngons on the sides, and unnecessarily subdivided in width direction.

All these things make harder to work with, Blender operators will misbehave, that is why you encounter these problems and are likely to expect further down the road.

Modelling applications generally like four sided faces, my advice is to start over with a better mesh base and work from there.

Bevel

Watch some beginner tutorials on hard-edge modeling and follow these guides for topology

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  • $\begingroup$ I used a modifier to get the object in its current form with its sphere-based top (see my previous question). Since modifiers are non-destructive, may this be a part of the problem? I know, the vertices of the sides don't build an even surface right now. Will I be able to clean up and rescue the object by adding a rough rounding as already seen on two edges? $\endgroup$ – t_w Aug 4 '16 at 6:16
  • $\begingroup$ Yes I saw your previous question, modifiers are generally good practice, but they tend to work on the whole model at once, so it may not work for your specific situation. In your case try eliminating the triangles on top, and removing doubles. Also make sure you applied the scale on your object, and see if it helps. $\endgroup$ – Duarte Farrajota Ramos Aug 4 '16 at 12:25
  • $\begingroup$ How can I eliminate the triangles on the top when I want to have a smooth surface derived from a sphere that still 3D-prints well with a detail level of 0.1 mm? What do you mean by applying the scale on my object? $\endgroup$ – t_w Aug 5 '16 at 1:53
  • $\begingroup$ Try under edit mode selecting all faces and using the operator Tris to Quads, by default Alt+ J $\endgroup$ – Duarte Farrajota Ramos Aug 5 '16 at 2:05
  • $\begingroup$ Under the Properties Shelf Nkey over the 3D view check the Scale parameter of your object and make sure it is 1,1,1 in all axis. If it is not, under object mode select your object and press Ctrl+A Apply > Scale $\endgroup$ – Duarte Farrajota Ramos Aug 5 '16 at 2:26
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I think you'd better use hard surface modeling technics here, keeping the amount of vertices you model the lower as possible and use a 'lot' of subdivision using the subdivision surface modifier.

I don't know if you have precise measurements or only the pictures shown in the comment of your question and global dimensions. Specially, what is the diameter of the large sphere you used before for the top face... so nothing will be accurate in what I can propose here.

I started from an open cube giving it a mirror and a subdivision modifier so that it has the overall shape you need (on the left here). Then added some cuts in the geometry to obtain the one on the right :

enter image description here

The principle is to cut where need move the cut to the angle so that it progressively gives the good shape and harden the edges (but keeping them beveled) :

enter image description here

Adding some more cuts allows you to obtain this kind of shape, with few vertices that you can use to influence the overall geometry.

Here mainly 6 vertices are needed to adjust the curve on the top. That can be easily tuned if you can make a precise blueprint of your shape, put it as background image and follow it as guidelines while adjusting the vertices positions :

enter image description here

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  • $\begingroup$ Thank you very much for your proposal! I have exact measurement I made with a digital caliper. Since this is my first productive 3D model, I think, I got quite far, and the bevel symmetry problem is resolved, I'm trying to stick with the bevel method. $\endgroup$ – t_w Aug 5 '16 at 22:38

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