# How to achieve clean Topology at joining edge of dissimilar features?

How can this topology be improved? Multiple attempts and several hours later, I have failed to create a successful all-quad mesh again. I keep trying to visualize face loops that define the edges I need on this object (a screw), but it is very difficult to join these dissimilar sections of geometry together. I have been watching tutorials/speed modelling sessions in an attempt to gain some further insight.

I am guessing that the round part needs to be spherical-ish, because if the verts are not distributed evenly, then it will appear lumpy instead of round/smooth...though clearly, the perimeter loop where the plus shaped area meets the round part has not-evenly-distributed verts all along that edge...

I tried to join the two edges and redistribute the verts to make them spherical, but it looks terrible. Here was that attempt (notice that the ridge is wavy and uneven...), I abandoned this approach after it seemed to be a lost cause:

And here is a later attempt, the round part is a bit lumpy/not-smooth...I also realized that there was a triangle here later on too (how would someone fix that? start completely over, since adding geometry would change the number of verts at the joining edge between the two surfaces?):

• you can select in edit mode and scale x to 0 Commented Jun 9, 2015 at 2:57
• The joining edge is intended to not be flat. It should be in the shape of a plus sign/cross, but shrink wrapped in the z direction to the surface of the spherical/dome shaped part. Commented Jun 9, 2015 at 3:09
• Can you post the .blend file? Also, a paintover image indicate the surfaces/profile you DO want would be helpful as well. Commented Jun 9, 2015 at 3:28
• Of course you can choose to devote time to minimize triangles and maximize quads. May I ask why that is a concern here? Will the object be highly animated with close up views? The UV sphere and Cone have triangles. Commented Jun 9, 2015 at 6:27
• The restriction to not allow triangles might be unfounded, if the Screw isn't being deformed and has nice smoothing then it's not likely to matter -- but you might have that one edge case when it does (if so elaborate..) Commented Jun 9, 2015 at 7:08

In Blender most of us would not model a screw by joining two separate meshes, one for the curvature and the other for the groove.

Other 3d packages such as AutoCAD / SolidWorks (and free alternatives) have a different internal representation of shapes. That's why boolean 'carving' is great for those kinds of programs. In those packages geometry remains a mathematical entity until converted to mesh-geometry for export.

In Blender we use mesh geometry (verts, edges, faces) all the way, and that means a different approach is worth considering. You've noticed that trying to match up two very different sections of mesh can be quite a hassle.

### Proportional Editing to the rescue!

I'd go for geometry roughly similar to this.

And the use Proportional Edition, move, to push the upper verts into that nice curve. Getting a dome curvature is the smaller problem with this kind of geometry. The biggest issue is thinking ahead about where you want sharp corners and you can do that as a flat surface first and extrude parts down later.

Enable proportional editing and press G to start moving, and Z to exclude the XY movement. Use Shift+Mouse wheel to adjust the sphere of influence. See the manual for more information about proportional editing .

The outcome: (with some corrections to the base)

• Above and below all quads with a shrink wrap.

• Please beware of impure and unchaste images below.

• Consider a boolean modifier A difference B. Sphere minus Cross Sign. You may have already done this. The cross sign has a bevel modifier.

• Press Apply. You may use a higher resolution sphere (more vertices) for a sharper result.
• OP wants clean topology, in this case I think your answer is a bit off.
– p2or
Commented Jun 9, 2015 at 6:50
• Boolean modifiers generate extra geometry, which is hard to control and especially not clean. To undestand what I mean, see: forums.newtek.com/…. Maybe mention that this is an alternative (fast) way of creating a screw. In addition, I would suggest using the boolean model as base for retopology, which makes sense in many cases to be more flexible in the design process.
– p2or
Commented Jun 9, 2015 at 8:22