In SketchUp, "cracks" in rounded corners typically refer to geometry failures where the mesh pulls apart or fails to form a solid face after applying a rounding extension. This is most often caused by modeling at a scale too small for SketchUp’s internal tolerance. The Core Issue: Geometry "Cracking"
SketchUp has difficulty creating very tiny faces (under roughly 1/16th of an inch). When you use an extension like Fredo6’s RoundCorner on a small object, the resulting arcs generate tiny segments that the software cannot bridge, leading to visible gaps or "cracks" in the mesh. Common Causes
Scale Limits: Modeling at real-world scale for small items (like jewelry or small hardware) often causes the engine to ignore tiny edges, leaving holes.
Coplanar Failures: If the edges being rounded are not perfectly aligned or if the faces are slightly "off-plane" (even by a thousandth of a foot), the tool may create fragmented, "cracked" surfaces instead of smooth ones.
Softening Errors: Sometimes the geometry is actually there, but the edges aren't "softened" or "smoothed," making the curve look like a series of broken, faceted cracks rather than a continuous surface. Solutions and Best Practices
The "Dave Method" (Scaling Up): The most reliable fix is to turn your object into a component, make a copy, and scale that copy up by 100x or 1000x. Apply the RoundCorner tool to the large copy—where SketchUp can easily handle the math—then delete it. The original, small-scale component will reflect the now-perfect geometry without the cracks.
Clean the Mesh: Before rounding, use native tools or plugins like CleanUp3 to ensure there are no stray edges or tiny "stubs" that could interfere with the corner calculation. sketchup round corner crack
Adjust Segments: Reducing the number of segments in your rounding settings can sometimes prevent the creation of segments so small that they "crack" the model.
Plugin Reinstallation: If the "crack" refers to a software error rather than geometry, ensuring you have the latest version of LibFredo6 and the specific extension is critical for modern SketchUp compatibility. Circles made of n sided ploygons cause endless issues
In SketchUp, "cracks" or missing faces during rounding typically occur when working with small-scale geometry or complex intersections. This happens because SketchUp's internal engine struggles to create faces smaller than approximately 1/64 of an inch (approx. 0.4mm). Common Causes of Geometry "Cracks"
Small Scale Geometry: When the rounding radius or the segments of the curve are too small, SketchUp fails to generate the tiny faces needed to complete the surface, leaving visible holes or "cracks".
Complex Intersections: Areas where multiple rounded edges meet can create irregular geometry that the standard algorithm cannot resolve cleanly.
Non-Coplanar Edges: If the edges selected for rounding are not perfectly aligned on a plane, the plugin may produce distorted or incomplete faces. How to Fix Cracks and Incomplete Geometry In SketchUp, "cracks" in rounded corners typically refer
Softening, Smoothing, and Hiding Geometry - SketchUp Help center
When searching for a "proper" feature to round corners in SketchUp, users are usually looking for a tool that is robust, doesn't break the geometry (creating cracks or black faces), and is easy to use.
While the term "crack" might refer to a specific plugin name you heard, it is more likely you are looking for the industry-standard solution to avoid "cracks" (geometry failures) when rounding corners.
Here is the breakdown of the proper features and plugins to achieve this:
If you have tried all the above and the extension still fails, you are likely dealing with a degenerate face. Here is the nuclear option:
Eraser + Shift to hide the problematic edges.Fredo6 – CurviShear or Artisan tools to manually rebuild the corner.Bevel (another Fredo6 tool) which handles complex intersections better than Round Corner.To fix the crack, you must understand the math. RoundCorner works by generating a massive amount of new geometry. A simple cube with a 1-inch fillet requires the software to delete the existing edge and replace it with dozens (sometimes hundreds) of tiny faces. Explode the group/component
Here are the top 3 reasons for the crash:
To understand the crack, you have to understand how SketchUp thinks. SketchUp is a surface modeler, not a solid modeler (like SolidWorks or Fusion 360). It uses "manifold edges"—meaning every edge should touch exactly two faces.
When you use Round Corner, the plugin performs a miracle: it trims away the sharp corner and stitches in a series of bezier curves and subdivided quads. However, due to floating-point tolerance (SketchUp struggles with math beyond 3 decimal places), the new rounded faces sometimes don't perfectly align with the old flat faces. The result is a microscopic gap—the crack.
Common Culprits:
High-resolution textures confuse the rounding algorithm. When you round an edge, the plugin tries to triangulate the texture coordinates. If a 4K wood texture is applied, the crash is almost guaranteed.