The Round Corner extension is still the best tool for the job. A "cracked top" is simply the extension telling you: "Your radius is too big, or your edges aren't clean."
TL;DR: Reduce your radius by 20%, turn on "Soften Edges," and you’ll have a render-ready model in seconds.
Have a different crack pattern? Drop a screenshot in the comments below.
Pros: Creates smooth, realistic geometry that is impossible to achieve manually in a reasonable timeframe. Cons: The "Crack Top" bug is real. It happens most often on complex corners or when the requested radius is too mathematically tight for the available space.
Final Score: 8/10 — Essential for visual rendering, but you need to understand its mathematical limits to avoid broken geometry.
If your RoundCorner plugin is leaving "cracks" or broken geometry on the top face of your SketchUp model, it’s usually due to tiny geometry errors or a conflict with the rounding algorithm. Quick Fixes for "Cracked" Faces
Scale Up (The "Dave Method"): SketchUp often fails to create small faces (under ~1mm). Scale your entire model up by 10x or 100x, run the plugin, and then scale it back down.
Check Hidden Geometry: Go to View > Hidden Geometry. You may find that the "crack" is actually an unsoftened edge or a missing tiny triangle. Use the Line Tool to manually stitch the gap, then use the Eraser Tool + Ctrl to soften the new edge.
Clean Your Mesh: High edge density or "stray" lines on the top face can confuse the plugin. Use an extension like CleanUp³ or Curvizard to simplify the edges of your face before rounding.
Upgrade to FredoCorner: The original RoundCorner is older; Fredo6 released FredoCorner specifically to handle more complex geometry with a better algorithm that reduces face-cracking. Alternative Manual Method
If the plugin continues to glitch, you can achieve a cleaner result manually: Draw a small arc on the corner of your face. Select the top face as your path. Choose the Follow Me tool and click the arched profile.
If you'd like, you can upload a screenshot of your model or describe the corner type (concave or convex) so I can give you more specific repair steps. Fredo6 Round Corner - Face becomes two tones - Extensions sketchup round corner crack top
Introduction
SketchUp is a popular 3D modeling software used by architects, interior designers, and product designers. One of the common issues faced by SketchUp users is the "Round Corner Crack Top" error. This report aims to provide an overview of the issue, its causes, and possible solutions.
What is Round Corner Crack Top?
The "Round Corner Crack Top" error occurs when using the "Round Corner" or "Fillet" tool in SketchUp to create rounded corners on a 3D model. The error causes the top surface of the model to become distorted or "cracked" when trying to apply a rounded corner.
Causes of Round Corner Crack Top
After analyzing various user reports and forums, the following causes have been identified:
Solutions
The following solutions can help resolve the "Round Corner Crack Top" error:
Workarounds
If the above solutions do not resolve the issue, the following workarounds can be tried:
Conclusion
The "Round Corner Crack Top" error in SketchUp can be caused by complex geometry, insufficient faces, or incorrect tool settings. By simplifying geometry, increasing faces, adjusting tool settings, or using alternative tools, users can often resolve the issue. If necessary, workarounds such as manual modeling or using third-party plugins can also be employed.
Recommendations
When the SketchUp Round Corner plugin (by Fredo6) causes "cracks" or holes on the top face of a model, it is typically due to the software's inability to form tiny faces or issues with non-planar geometry. SketchUp Community Why Cracks Happen Tiny Geometry Errors
: SketchUp cannot create edges shorter than 0.001 inches. If your rounding offset is small, the plugin may fail to create the necessary "micro-faces," leaving holes. Non-Planar Faces
: If the top face isn't perfectly flat, the plugin may struggle to resolve the intersection of rounded edges, causing fragmented geometry. Overlapping Offsets
: 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)
: Scale your entire model up by 10x or 100x before applying Round Corner. Once the operation is complete, scale it back down. This bypasses the tiny geometry limitation. Manually Healing Faces
: If holes appear, you can often "heal" them by redrawing a single missing edge with the . SketchUp will usually re-generate the missing face. Check Hidden Geometry View > Hidden Geometry
to see where edges are failing to connect. You can manually draw connecting lines (triangulation) to patch holes in curved surfaces. Change Border Settings : In the Round Corner parameters, try setting borders to
instead of "Softened/Smoothed" to prevent the softening algorithm from creating visual artifacts or "two-tone" face issues. Use FredoCorner : Consider switching to FredoCorner
, which is a more advanced version of the tool designed to handle complex corners and non-planar faces more robustly. SketchUp Community The Round Corner extension is still the best
Round corner doesnt work correctly - Extensions - SketchUp Community
This works for simple cracks where a single face is missing.
Limitation: This only works for single, small cracks. If the entire top rim is jagged, move to Method 2.
If you are trying to do this without plugins and your geometry is breaking (cracking):
If you were looking for something else (like a specific tutorial link or a texture file), please clarify the question!
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
Before running Round Corner:
If you’ve modeled a box, table, or curved object in SketchUp and noticed a thin crack or seam along a rounded corner on the top face, you’re not alone. That visual artifact often happens when edges, faces, or smoothing settings don’t align perfectly after rounding or chamfering. This post explains why it happens and gives clear, actionable steps to fix it so your model looks clean and exports correctly.
When you apply a RoundCorner (Fillet) operation to a shape—specifically a box or rectangle—the plugin successfully rounds the vertical edges. However, users frequently report that the top surface splits open or creates a jagged hole/crack right in the center of the face or at the corners.
Instead of a smooth, closed box, you are left with a model that looks like the top was ripped open.
If you are looking at a cracked top right now, do not panic. You do not need to re-model. Here are three repair methods, ranked from easiest to most advanced. Have a different crack pattern