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My goal is to create something like a "lark's tongue chamfer" along part of each of 4 edges of a cuboid. This would involve a bevel that has a variable depth that forms a smooth curve, starting at 0 depth, reaching some peak depth at the middle, and then returning to 0 at the other side. The main thing is that I would like to know different ways to control the depth as a curve.

Here's an example, sort of following a circular curve, but other shapes ("smooth", "sphere", "root", etc) would be desirable:

Lark's tongue chamfer next to mesh with a similar varying bevel depth

I've created this mesh, but my procedure was long and convoluted, and I'm sure there's a better way someone can suggest.

Additionally, can someone clarify for me: (a) Is there a name for this sort of bevel, chamfer, or shape in general?; (b) Later I want to round off all of the sharp edges (i.e. with a tiny bevel) and I want to (say) subdivide the surface to smooth it out, and for this I understand it might be important to avoid having the triangles shown in my image above, so what should be done about this?

Anyway, below is what I did, including screenshots of key steps. Apologies if the screenshots are not very clear at their default size, but the image itself is available as a larger version. Note that units are in metres...

  1. Image A: Create a 2-metre plane, and go into Edit mode. Subdivide the face 8 times, creating a sheet as a 9x9 grid
  2. Duplicate and move up by a known fixed amount on Z axis (e.g. 0.2m)
  3. Image B: Repeat, duplicating the sheet copy that was made in step 3
  4. Image C: Select the edge loop of the top-most sheet, then hide all but this selection (SHIFT+H). Go to top view, then select the middle-most edge segment of one side
  5. Image D: Turn on Proportional Editing, set to "Sphere" mode. Move the selected edge inwards (i.e. on the X axis only) by 0.1, setting the proportional size to (say) 0.55
  6. Image E: Repeat with the other 3 sides
  7. Image F: Unhide everything with ALT+H. Select everything in the middle sheet now
  8. Image G: Hide everything else with SHIFT+H. Go to top view, then select and delete all interior edges, leaving just the square outline edges. Select the middle edge of each side of the square
  9. Image H: Go to side view and then move these edges again, this time down by -0.1 on Z axis with proportional size still the same as above
  10. Image I: Unhide everything with ALT+H. Select all edges of the top sheet
  11. Image J: Move the top sheet down to superimpose it on the middle sheet (making sure to turn off proportional editing)
  12. Image K: Select the edge loops of the top sheet, and also the edge loops of the middle sheet
  13. Image L: Click RMB and select "Bridge Edge Loops"
  14. Image M: Select the edge loops of the middle sheet, and also of the bottom sheet, and then Bridge Edge Loops there, too
  15. Image N: Select all, and then Mesh => Cleanup => Degenerate dissolve. Fix normals with SHIFT+N. Deselect all, and we're done!

Visual demonstration of the steps above

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What an amazingly detailed post!

Would something like this work for you?

  • To save too much adjustment in separate places, starting with 1/8 square tile, open on all the sides you can't see, here...
  • Assign Edge Bevel weights to the edges shown in shades of blue, all at 1 will do to start with...

enter image description here

  • Assign 2 Mirror modifiers, one about the Empty rotated in Z by 45, and another in X,Y,and Z.

enter image description here

  • Assign a Bevel modifier, by width, limited by Weight, segments about 5, with a profile of about 0.15

enter image description here

  • Assign a second Bevel modifier, to hold the sharp edges under subdivision,limited by Angle, up around 80 degrees, and a Subdivision Surface modifier.

enter image description here

Tweak the Edge Bevel weights, and other Bevel parameters, to get the scalloped shape you want. If you can't get all the way there, you may have to apply the first Bevel modifier, and tweak that in the geometry, by hand.

Edit: Just noticed your first Bevel should probably have only 1 segment..

enter image description here

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  • $\begingroup$ Oops, looking a bit harder at your question, the first bevel should have only 1 segment, for flatter scallops. $\endgroup$ – Robin Betts Nov 27 '20 at 14:30
  • $\begingroup$ Great versatile answer, Robin! For other depth profiles, it'd be great to assign or define the edge bevel weights (your 2nd step) in some assisted/procedural way, rather than typing in a "by-eye" or hand-calculated distinct value for each one. I'm thinking like a function, or a ramp value, or one of the in-built falloff methods used by proportional editing. It doesn't look like edge bevel weights support Drivers, so do you know of any alternative way to assign different values in bulk? $\endgroup$ – algofoogle Nov 28 '20 at 2:27
  • $\begingroup$ @algofoogle Interpolation of edge bevel weights is a tricky issue ... I can't think of anything off the cuff .. I would be looking at using the percentage setting for bevels, to control with topology, use of the Data Transfer modifier with some kind of template or a script / add-on. For the latter, you would have to decide how you would like to interact with it, and maybe how to give the tool the greatest possible generality, (maybe across other attributes of a mesh, as well?) $\endgroup$ – Robin Betts Nov 28 '20 at 9:36
  • $\begingroup$ Great, thanks Robin :) $\endgroup$ – algofoogle Nov 28 '20 at 12:56

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