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Published Date:

by S68
who, in the real word answers to the name of Stefano Selleri
www.selleri.org
selleri@det.unifi.it
28-01-2003

Introduction
Some weeks ago I published a Knife script (available at my site) able to cut into two pieces a mesh along a plane, preserving quadrilateral faces whenever possible. This tutorial explain an ‘advanced’ utilization of the tool for architectonic bevelling.
The Beveling
Say that you wont to do some sort of obelisk or other shape of complex profile. If you plainly extrude the profile or spin it you might get what you want, but edges will be sharp. The workaround is to model the section, not
the profile, and extrude rather than spin, but this is unsatisfactory inasmuch:

1. Modelling the profile allows you greater control on the profile itself. You can easily make the profile follow circles like in many column capitols etc.


2. The bevels you get by extruding the section have a radius of curvature
which varies when you scale up and down the section itself. This is unappropriate since bevel radius tipically stays constant.

The solution here proposed allows for adding bevels working with profiles.
Let’s assume you are doing a triangular obelisk. You have made your profile and you have spun it on 360° with 3 repetition. The first thing to do is to take one third of it S68 – Beveling With the Knife Tool 2/3 (applying the knife tool twice) so that we can bevel just one edge, and then SpinDup the result.
If possible it is even smarter to take half of that, since the bevel will be in most cases symmetric. Let’s assume that we drop the upper half. Then we drow a plane passing through the center and through the edge, and dup it three times.

Dups are to be shifted of an equal incremental quantity in a given direction. In this example each duplicate is shifted along y of –0.01 blender units.
We will use these duplicated planes (not the original one, that’s superfluous, to add nodes in the right position to bevel.

The mesh is cutted with the knife tool by all three duplicate planes, so to have, in the end a big portion of mesh remaining and 3 slim slices.
The four meshes are then Joined (J Key) and duplicate nodes ar removed. The missing half is easily reconstructed via mirroring and rotation.
DO NOT use the ‘Smooth’ button, you’ll spoil everything! Rather, rotate the mesh so that the edge still to be bevelled is aligned with one coordinate
axis and select all the inner new vertices. I mean, all the new vertices except the leftmost and rightmost row of new ones and except those vertices lying on the boundary of the region, the ones (on the top in the
figure) which should not be moved since they should match with other vertices afterwards, when you will spin the thing.

Now move these selected slightly upwards. Deselect the rightmost and leftmost column of vertices and move the remaining selected vertices another bit upwards. Repeat until you are left with just the central column of selected verices

You should remain with something resembling to the figure here on the right. Now the most is done. You have to SpinDup or whatever your mesh. In this case SpinDup over 240° 2 duplicates, remove doubles and admire your perfectly bevelled obelisk.

Conclusions
Here is an advanced bevelling technique for profile-based modelling.
Happy blending!

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