When a plugin attempts to round a corner where multiple complex angles meet, it encounters several limitations:

: Use RoundCorner on the large copy. Because the geometry is now huge, SketchUp has no trouble creating all the faces.

Ensure your offset value is physically possible. If your top surface is only 10mm wide, a rounding radius of 6mm from both sides will overlap and destroy the top face. Lower the radius.

SketchUp cracks or missing faces during rounding occur when geometry falls below the application’s 0.025 mm tolerance limit, commonly resolved by scaling up the model by 100x or 1000x before applying the RoundCorner tool. Alternative solutions include reducing the segment count or switching to the more robust FredoCorner plugin for complex intersections. To learn more about fixing these issues, see the discussion at SketchUcation . Round Corner Issues | sketchucation

Look for unexpected dashed lines cutting across your top face.

Round corner doesnt work correctly - Extensions - SketchUp Community

If the top face cracks into triangles, it means the surface is no longer perfectly flat. Activate the tool.

When a rounded corner "cracks" or breaks at the top, it typically boils down to one of four issues: 1. Geometry Scale Limitations

If you need a perfectly smooth, crack-free top (like a car fender), stop using Round Corner for the top vertex. Use or SubD (Subdivision) .

: If the rounding radius is too large for the surface area, the geometry "self-intersects," which often breaks the top surface. SketchUp Community How to Fix Cracks The "Dave Method" (Scaling Up)

Those unsightly seams, overlapping triangles, and "pinched" vertices on the flat top surface can ruin a otherwise perfect rendering. But don't worry—this isn't a bug in Round Corner; it’s usually a geometry logic issue.

This issue is most common in these scenarios:

To solve the , you need to think like the plugin. Fredo6’s Round Corner works by creating three sets of geometry:

Close the group. Activate the Scale Tool again, drag a corner grip, type 0.01 (if you used 100x) or 0.001 (if you used 1000x), and press Enter . Your model is now perfectly rounded at its original scale. Method 2: Repairing Missing Top Faces Manually

Hover over the edges of your tabletop to highlight them, click to apply, and press the Enter key to finalize. Alternative Native Solutions: Follow-Me Tool