If you are trying to visualize the fix:
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.
Use this if the model looks fine in SketchUp but breaks when you export/slice it.
Title: Round Corner looks fine in SU, but the STL export has a cracked top
Body: I used Round Corner to fillet the top rim of a solid group. In SketchUp, the smoothing looks perfect. However, when I export to STL (or render in V-Ray/Enscape), there is a visible crack or missing polygon on the top edge.
Screenshots: [Attach image of the crack]
What I’ve tried:
The Fix: The issue was that Round Corner created internal hidden geometry that wasn't welded. I had to:
Alternatively, reducing the Offset value in Round Corner to 0.001" instead of 0 fixed the crack.
Post: Struggling with the SketchUp Round Corner extension? 🧩
If you get a "cracked top" (faceted artifacts on a flat surface after filleting), here is the fix: sketchup round corner crack top
👉 Turn OFF "Triangulate" in the advanced settings. 👉 Or, apply the fillet before punching a hole in the top face.
The extension is powerful, but it hates Ngons that aren't perfectly planar. If the crack persists, use Curvizard to weld the perimeter after rounding.
#SketchUp #3DModeling #Tips #RoundCorner
Which image should I attach to this post?
To write a helpful essay or article for you, I need to know which topic you are referring to, as your request is slightly ambiguous. Could you please clarify if you mean: Digital 3D modeling:
Solving geometry tearing, missing faces, or visual "cracks" when using tools or plugins like RoundCorner Physical repairs:
Fixing a physical fracture or crack on the rounded corner of a countertop, table, or surface?
Please tell me which one you are looking for so I can provide the correct content! How To Round Edges In Sketchup
The "cracked top" issue in SketchUp usually happens when rounding edges—whether manually or with a plugin like RoundCorner
—because the geometry is too small, overlapping, or contains microscopic gaps. Common Causes of Geometry "Cracking" Scale Issues If you are trying to visualize the fix:
: SketchUp struggles to create faces smaller than ~1mm. If your radius is small, the geometry "fails" and leaves holes or cracks in the top surface. Overlapping Edges
: If a rounded corner intersects with nearby geometry (like a hole or another edge), the plugin may fail to close the face properly. Non-Coplanar Faces
: If the top surface isn't perfectly flat, rounding the edges will force the geometry to twist, creating "cracks" or triangulated shards. SketchUp Extension Warehouse Step-by-Step Fixes The "Scale Up" Trick Select your object and make it a Copy the component and scale the copy up by 100x or 1000x Perform the "Round Corner" operation on the giant copy.
Delete the giant copy; the original-sized component will now have the perfectly healed, rounded geometry. Increase Segment Count
If the "crack" looks like a jagged edge, select the arc or curve and go to the Entity Info Increase the (e.g., from 12 to 24 or 48) to smooth out the transition. Check for "Z-Fighting"
If the top looks like it's flickering or "cracking" visually, you might have two faces occupying the same space. Delete one of the overlapping faces or move one slightly. Manual Healing
to draw a line across the "crack." This often forces SketchUp to re-calculate and close the missing face. After the face closes, delete the extra line. Alternative: Non-Destructive Rounding If you only need the corners to rounded in a final image, use a rendering engine like Asset Editor and select as the texture. Adjust the
to simulate rounded edges without actually changing your 3D geometry. Further Exploration official SketchUp Guide
for softening and smoothing geometry to hide existing cracks. Extension Warehouse to download the latest Fredo6 RoundCorner plugin which includes automated repair tools. this quick tutorial
on how to fix jagged edges by adjusting segment counts in the Entity Info tray. If you’ve modeled a box, table, or curved
tool method for rounding corners without using any external plugins? AI responses may include mistakes. Learn more
Based on your search, it sounds like you are looking for a review of the FredoScale RoundCorner plugin for SketchUp, specifically investigating a known issue where the geometry creates a "crack" or hole on the top surface after applying the rounding effect.
Here is a solid review of the plugin with a specific focus on that cracking issue, why it happens, and how to fix it.
Do not apply a 2-inch radius in one click.
If Fredo6 Round Corner consistently cracks your top geometry, switch to these alternatives:
Developer: Fredo6 Purpose: Adds fillets (rounded edges) and chamfers (beveled edges) to 3D geometry.
For years, this has been the "gold standard" plugin for SketchUp users wanting to make their models look less boxy. However, it is not without its quirks, the most frustrating of which is the Top Face Crack.
The SketchUp round corner crack top issue is a rite of passage. It signifies that you are pushing organic geometry inside a polygon-based engine. By understanding the "Ngon limitation" and adopting the Sandwich Workaround or adjusting your plugin segments, you can produce watertight, 3D-printable, and render-ready models.
Remember: When in doubt, scale up (to give math room) and increase segments (to smooth the math). Do not fight the crack; engineer your workflow to avoid it.
Do you have a specific model that keeps cracking? Drop your file parameters (units, radius size, segment count) in the comments below for a custom diagnosis.
I have written two versions depending on the exact nature of your problem.