New user to Rhino here and first time poster.
I am trying to model an iPhone in Rhino just as a good learning process for modeling and handling CAD measurements and tight tolerances etc. The iPhone has a lot of radius corners and radied (?) cut outs in the metal body. These are the details I am trying to re-create in my model with high fidelity. As we all know nothing really has 90 degree sharp corners, and as such I am adding small fillets to every edge of the model.
The problem is, that when I make a cut out into a solid flat surface, with a rounded edge line, or object, and then fillet the resulting top-edge line of this cut out, the fillet sort of reduces the overall quality of the model and is not meeting my expectations for what the result should look like.
Overview of final example model;
Below are two screenshots showing the “problem”;
Corresponding to the results of point 8 in steps below.
Corresponding to the results of point 11 in steps below.
Example from my test model of the iPhone;
My Rhino version is : (5.9.40617.14345, 2014-06-17)
Steps To Reproduce;
Start a new project with template Small Objects - Millimeters
Create a solid box from 0, with 15x15x15 dimensions
Create a rounded rectangle from 0, with 8x3 dimensions and a corner arc of 5
Position the rounded rectangle roughly in the center of the box and slightly above the top surface of the box
Create a cut out in the solid box with the rounded rectangle shape. You can use either MakeHole, WireCut or Extrude and Cap the rounded rectangle and do a Boolean Differense in the box to create a cut out. The depth should be about 3mm down into the box.
Fillet the top edge line of the rounded rectangle with a radius of 0.25mm using the FilletEdge command.
Zoom in to the rounded rectangle cut-out fillet and Observe the corner smoothness of the fillet edge. The quality of the fillet resolution is sub-par. (Use Shaded view or Rendered view, Perspective). The isocurve outlines intersect with the shaded box model mesh, meaning that the fillet edge detail is lower than that of the rounded rectangle curvature.
Re-create this experiment but alter the rounded rectangle with the Rebuild command and set the values to;
Point count: 256
Degree: 11 (not sure if this affects the outcome or not, but just because we can, lets max it out)
Perform steps 6 -> 8 again.
Note that the fillet edge does not have a 1:1 cross-section curvature to the rebuilt rounded rectangle. There are more lines but the visual appearance of the fillet radius quality remains the same.
I tried using various methods and points and degrees and it never really comes out looking like I would expect, i.e. a near perfect, high resolution filleted edge.
The quality does increase a bit with higher Rebuild values, but it’s not “perfect” and I can’t really find a good intermediate value where I get acceptable results vs. creating a too “dense” model.
I realize most people model quality after the intented purpose for the model, but I thought with a CAD program like Rhino you wouldn’t have to compromise…
I also had a file from a training video which has this exact type of modeling done to it, and in this excercise file model, the same imperfections can be observed.
- Am I doing something obviously wrong here which is affecting my quality of the radious fillet edge? Can I create the fillet a different way (automatically), or is there a setting which can be used to increase the quality of the fillet edge?
- Is it expected and acceptable that the filleted radious curvature of this nature has these types of imperfections?
I would prefer not having to rebuild these fillet edges manually for all corners I am doing this for.
But if this is as good as it can get with automated fillet, I am truly suprised and the low-resolution of the resulting mesh.
Obviously it is only really visible if zoomed in to a certain extent, but even with the full object in view I can still see hints of this imperfection.
I have searched for information about this on Google and on this as well as the old Rhino forum and found nothing that relates to my questions above.