Sketchup Round Corner [upd] Crack Top

In SketchUp, "cracking" on a rounded corner or top face often occurs when geometry is forced out of its 2D plane or when faces are too small for the program to render correctly Why "Cracks" Happen Non-Coplanar Faces

: If you manually move an edge or vertex even slightly (e.g.,

feet), SketchUp creates "cracks" (softened or hidden lines) to triangulate the surface because it can no longer be a single flat face. Tiny Face Issues : SketchUp has difficulty creating very small faces (under

). When rounding a corner with a small radius, the geometry may fail to close, leaving a visible gap or "crack". How to Fix or Create the Piece

To create a piece with clean, un-cracked rounded corners, follow these methods: 1. The "Dave Method" (Scaling Up)

Use this to avoid the "tiny face" problem when creating small rounded edges. Turn your object into a Make a copy of that component and scale it up by sketchup round corner crack top

Perform the rounding operation (using tools or plugins) on the giant copy.

Close the giant component and delete it; the original-sized component will now have the geometry perfectly formed without cracks. 2. Manual Method (Native Tools) For those without plugins, use the tool to ensure clean geometry. Draw the Profile : Draw a small arc on the corner of your face. Select the Path : Select the top edges of your piece that you want rounded. Apply Follow Me : Click the

tool, then click the small corner arc profile. This "sweeps" the roundness along the top, creating a clean edge. 3. Using Extensions Extensions like RoundCorner FredoCorner

by Fredo6 are designed to handle complex intersections that usually cause manual cracking.

5. Use "Sharp" Offset Mode

In the Round Corner toolbar, look for the Offset type (usually under Advanced settings). In SketchUp, "cracking" on a rounded corner or

• Switch from "Round" to "Sharp" or "Linear" .
• This changes how the fillet transitions into flat planes, often preventing the pinch that causes cracks.

Option 1: Modeling a "Cracked/Broken" Round Corner (The Design Effect)

If you want to make a rounded corner look like it has been chipped, damaged, or cracked, follow these steps:

Prerequisites:

• You need a shape with rounded corners. If you don't have one, use the RoundCorner plugin by Fredo6 (highly recommended) or the native "Arc" + "Follow Me" tools.

Steps to create the crack:

1. Create the Basic Shape: Draw your rectangle and round the corners using your preferred method.
2. Draw the Crack Profile:
   • Select the Freehand Tool (pencil icon with a curve) from the Large Tool Set.
   • Draw a jagged, irregular line across the top face, extending over the rounded edge and onto the side face. This represents the crack line.
3. Create the Void:
   • Use the Push/Pull Tool.
   • Push the face created by your jagged line inward. If you want a deep crack, push it all the way through. If you want a surface chip, push it slightly in.
4. Add Realism (The "Top" Detail):
   • To make the "top" look cracked, use the Rotate Tool to tilt the broken face slightly downward.
   • Use the Move Tool to slightly offset the broken geometry so it doesn't look perfectly aligned (simulating a break).
5. Texture:
   • Paint the inside of the crack with a darker color or a "rough" texture to distinguish it from the smooth surface.

3. Avoid "Sharp" Offset on Tops

In the Round Corner dialog, you have "Round" (smooth) and "Sharp" (flat miter). "Sharp" frequently creates the crack top. Use Round with a low segment count (3-4 segments) for tops.

Part 1: What is the "Round Corner Crack Top"?

Before fixing the problem, you must understand it. The Round Corner plugin works by offsetting, extruding, and stitching geometry. When you apply a fillet to a hard edge, SketchUp’s geometry engine (based on polygons, not true NURBS curves) must triangulate complex intersections. Switch from "Round" to "Sharp" or "Linear"

The "crack top" specifically occurs when the rounding algorithm fails to properly cap or weld the vertices on the uppermost horizontal plane. Instead of a continuous surface, you get:

• A missing triangular face (a literal "crack").
• A reversed face (blue instead of white).
• Z-fighting (two overlapping faces flickering).

This is most common when:

1. Rounding a cube where the top face has a hole or an inserted component.
2. Rounding a cylinder with a high radius that exceeds the top face's thickness.
3. Using "Sharp" offset (Flat) instead of "Round" (Bevel) on non-uniform geometry.

How to Fix / Prevent the Crack

If you are running into this issue, try these troubleshooting steps before giving up on the model:

• Reduce the Segments: High-segment arcs (making the curve very smooth) exponentially increases the calculation load. If you are rounding a complex shape, lower the number of segments. A smoother look is not worth a broken model.
• Check the Radius: Ensure your radius isn't larger than the thickness of the material. It sounds obvious, but this is the #1 cause of top-face blowouts.
• Clean Up First: Run a "Cleanup" plugin or manually delete stray lines on the face before applying the tool.
• The "Stick" Trick: If the top face keeps cracking, draw a single diagonal line across the top face before running RoundCorner. Sometimes this helps the plugin understand the surface definition better.

Part 4: Prevention – How to Avoid the Crack Altogether

The best cure is prevention. Here is your pre-flight checklist before using Round Corner on a top face.