Mesh vs surface - control points & edges

i’m creating faceted surface but also need to chamfer edges, if i use mesh i cant chamfer and if i use surfaces the edges don’t remain straight… tbh i’m still not sure on the best use of mesh vs surface

Below is an example of typical comparison, moving point highlighted in green
mesh keeps EDGE A straight
surface starts to bend EDGE A (and all the edges associated )

Can edge on a surface be fixed to change as a facet?

It is difficult to answer your question without having a file with the geometry. You can upload a .3dm file by dragging the file to the window where you type a post, or click on the vertical arrrow icon above where you type a post.

How did you create the surfaces?

okay, i just added a small file with this shape on, i think i must have made the surface from the mesh (meshtoNURB) but there’s edit i want to do like chamfer that i cant do with the mesh so it feels like the workflow gets repeated everytime i change the original shape

Shape_Test.3dm (2.2 MB)

Try laying our your object with curves 1st insuring they are all straight, then use planar surfaces to create the shape. It looks like you are lofting, or using edgesrf… planar will get you a better result IMO.

The triangular surfaces are trimmed degree 1 quad surfaces. Both MeshToNURBS and PlanarSrf will produce these surfaces. This is the cause of the curvature when moving a control point.

When a control point of a planar degree 1 quad surface is moved out of plane the surface becomes warped and is no longer planar even though the edges remain straight lines. Then a warped quad surface is trimmed to be a triangular surface one edge of the trimmed surface will be curved. That is inherent in the geometry of warped surfaces.

Use MeshToNURB with TrimTriangularFaces=No The result will be untrimmed triangular surfaces with one zero-length edge. When a control point is moved the surface will remain planar. The disadvantage of using untrimmed triangular surfaces is difficulties can occur in extending the surface and similar.

thanks informative and helpful
i’m not sure if it better to be working in mesh or surfaces, does it really matter

just one more question, if i wanted the surfaces to curve how do i get the edges all to follow so the geometry stays closed? when the surface is joined no control points are active

Try this.

MeshToNURB with TrianglularFaces=No
Explode the resulting polysurface
SelSrf all the exploded surfaces
Rebuild as single splan surfaces with Points = 3 and Degree = 2 or Points = 4 and Degree =3
When editing edges select all control points at the same location to move together or nudge together
If you don’t move all the control points at the same locaiton together then drag control points until they are at the same location with Point Osnap on, or use MatchSrf with Closest points and Refine match off, and Isocurve direction automatic. If 3 points per surface then use only position matching. If 4 points per surface use position or tangency matching.

You will need to refine the render mesh settings to prevent apparent gaps from appearing.

That’s great thanks, seems to move about without any issues

assume i have to keep the shape exploded in order to manipulate the control points