Hi Jay,

> I know the "ShrinkTrimmedSrf" command and it works well but not with these surfaces wich were
> generating by a Chamfer. Is this normal?

Yeah it's normal for a case where there's a trim curve that's slicing a kind of diagonal piece of the surface off. ShrinkTrimmedSrf can only shrink things down to the UV space bounding box around the trim curves. Basically a little piece of the trimming boundaries is not aligned with the UV isoparms in your case here.

You can kind of more easily see what's going on by turning on surface control points, which look like this at the end:



Another way to describe is that ShrinkTrimmedSrf will only shrink things by Isoparm directions, an Isoparm is a curve going in the U or V directions of the surface control point grid, so in your case here the kind of isoparm cuts would be like this:




You can see there that with those kinds of cut directions, you can't shrink this down anymore without also cutting off some of the active area of the surface. This is because the end trim is going diagonally across UV space instead of being in an isoparm direction.

Why is it that you're trying to shrink these things down in the first place? Are you trying to edit a solid made up of booleaned together parts by manipulating surface control points? Because if so that's just not generally how you model things in MoI, that's more of how you do things in a polygon modeling program. MoI is focused on different techniques than that, more on making things from 2D curves and not on 3D control point manipulation.

Also see this FAQ for some more explanation on control points and trim curves:
http://moi3d.com/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

- Michael