SketchUp

RoundCorner by Fredo6 — Paid SketchUp Plugin: 3 Modes Explained

Posted on by Nguyen Huu Khanh
17
Aug

Rounded corners are one of the most common finishing touches in furniture and product modeling, yet SketchUp has no built-in fillet command. The go-to solution for most modelers is the RoundCorner extension by Fredo6 — a paid plugin (perpetual license via Sketchucation) that rounds, bevels, and chamfers edges in one tool. This guide covers the full workflow: the native Follow Me arc method for simple cases, RoundCorner for bulk filleting, and a quick comparison so you know which technique to reach for. Whether you are rounding the legs of a dining table or chamfering the frame of a cabinet door, understanding all three approaches gives you precise control over edge quality and polygon count.

RoundCorner works in SketchUp 2017 through 2026 and requires a paid perpetual license — purchase at Sketchucation. LibFredo6 (the required companion library) is free. The toolbar exposes three distinct operations — Round (circular fillet), Bevel (flat chamfer), and Sharp (no rounding, re-creates crisp edges after cleanup) — and all three are driven by the same two parameters: offset (fillet radius) and segments (polygon resolution of the curved face). Most tutorials only show the Round mode, so the Bevel mode for furniture chamfers and the Sharp mode for fixing stray geometry go largely unnoticed.

The native Follow Me technique predates every plugin and requires no installation. You draw an arc profile on a face perpendicular to the edge you want to round, then use Follow Me to sweep that profile along the edge loop. It produces clean, predictable geometry with no triangulation, but it is tedious on anything with more than a few edges. Manual arc bevel falls in between: you draw a bevel cut across the corner with the Line tool and the Arc tool, which gives you one clean quad face per corner but scales poorly beyond four or five corners.

Key Features

  • Three edge treatment modes in one toolbar. Round corner produces a cylindrical fillet (quarter-circle cross-section) along the selected edges. Bevel creates a single flat cut, equivalent to a chamfer, which is ideal for furniture that needs a machined look rather than a smooth curve. Sharp mode reconstructs the corner geometry without rounding — useful when you want to clean up near-zero edges left by other operations without changing the silhouette. Each mode uses the same offset and segment inputs, so switching between them is instant.
  • Per-edge offset control via the red/orange highlight step. Before RoundCorner commits, it highlights every selected edge in the preview. Clicking an edge while it is highlighted toggles it between active (orange) and excluded (red). This means you can round 90 percent of a model’s edges in one pass and leave specific corners sharp — a detail that matters in cabinetry where the back edges of a unit are never seen and rounding them only adds unnecessary polygons.
  • Offset is the fillet radius, capped by geometry. The offset value is the inscribed-circle radius of the two faces meeting at the edge. If you type 50 mm the curved face will have a 50 mm radius. The hard limit is half the shortest face the fillet has to cross — exceed it and RoundCorner either silently skips the edge or flags an error. On thin panels (e.g., a 10 mm door frame) keep the offset under 4–5 mm to avoid conflicts.
  • Segment count controls polygon density. The default segment count is usually 4 or 6, which produces a faceted curve that looks smooth enough in most views. Increasing it to 12 or 24 produces a smoother arc but multiplies the face count proportionally. For furniture destined for a photorealistic renderer, 8–12 segments is a practical ceiling; for construction documents displayed in a style with edges hidden, 4 segments is sufficient.
  • Concave inside corners stay round regardless of mode. When two faces meet at an inside (concave) angle, RoundCorner always applies a Round fillet even if the toolbar is set to Bevel. This is by design — a flat bevel on an inside corner would require geometry that overlaps, which SketchUp cannot represent. Knowing this in advance prevents confusion when a model has both inside and outside corners and you expect all chamfers to be flat.
  • Dependency on LibFredo6 — silent failure without it. RoundCorner will install and the toolbar will appear even if LibFredo6 is missing. The tool launches but does nothing when you click. Both extensions must be in the Plugins folder and SketchUp must be fully restarted (not just the extension manager refreshed) before they load correctly. This is the single most common setup problem reported on Sketchucation.

How to Install and Use

  1. Purchase and download from Sketchucation. RoundCorner requires a paid perpetual license — go to sketchucation.com/plugin/1173-roundcorner to purchase and download the .rbz file. Then search for “LibFredo6” (free) and download it separately. Do not rename either file.
  2. Install LibFredo6 first. In SketchUp, go to Extensions > Extension Manager > Install Extension, browse to the LibFredo6 .rbz, and click Open. Wait for the success message. Then repeat the same process for RoundCorner. Order matters because RoundCorner’s loader checks for LibFredo6 at startup; installing RoundCorner first and LibFredo6 second leaves them out of sync until the next restart.
  3. Fully quit and relaunch SketchUp. Close SketchUp completely — not just the model, but the application. When it reopens, the RoundCorner toolbar should appear automatically. If you do not see it, go to View > Toolbars > RoundCorner to enable it manually.
  4. Select the geometry you want to round. You can select individual edges, entire faces, or the whole model (Ctrl+A / Cmd+A). A selection that includes faces is fine — RoundCorner only operates on the edges in the selection. For a first test, select a single rectangular solid and press Ctrl+A to select everything.
  5. Click the Round Corner button in the toolbar. The preview highlights all selected edges in orange. At this point you can adjust the offset by typing a number in the measurement box at the bottom of the screen (e.g., type “10mm” and press Enter). The segments field accepts a count; press Tab to move between offset and segments.
  6. Exclude edges you want to leave sharp. Click any highlighted edge to turn it red (excluded). Click it again to re-include it. This is the step most first-time users skip, and it is the reason their models come out over-rounded — the back edges of a shelf unit or the inside of a rabbet do not need rounding.
  7. Click anywhere in empty SketchUp space to commit. The extension applies the fillet and exits preview mode. The result is a dense triangulated mesh. Immediately run Edit > Select All then use the Soften Edges dialog (Window > Soften Edges or right-click > Soften/Smooth Edges) and drag the angle slider to about 20–30 degrees to hide the diagonal triangulation lines. This step is not optional for a clean rendered or exported model.
  8. Follow Me native method (alternative for single edges). Draw a perpendicular face at one end of the edge — a small rectangle. On that face, draw an arc at the corner with the Arc tool (set to 4–8 sides), deleting the corner triangle it replaces. Then draw the path loop with the edge loop selected, activate Follow Me (Tools > Follow Me), and click the profile face. SketchUp sweeps the arc around the entire loop in one operation. The result has no triangulation and needs no softening, but the process is slow for complex models.

Pro Tips

  • Run RoundCorner last, on finalized geometry. The plugin is sensitive to near-zero-length edges, coplanar faces, and reversed face normals. These issues are common in work-in-progress models but easy to ignore when you are still designing. Before running RoundCorner, go to Window > Model Info > Statistics > Fix Problems and also run Edit > Delete Guides. Overlapping geometry that looked fine at normal zoom will cause RoundCorner to crash or silently skip edges. A clean model produces a clean fillet in one pass; a messy model may require five retries.
  • Use Bevel mode for furniture chamfers instead of Round. Round mode adds a curved face that can look soft and plastic on furniture pieces like table edges or cabinet doors. Bevel mode produces a single flat cut — a true chamfer — which reads as a machined or hand-routed edge in renders. The polygon cost is also lower: one flat face per edge versus N faces (where N is the segment count). Switch to Bevel for any piece where you want a mid-century or industrial look rather than softened edges.
  • Keep offset under 3 mm for fine joinery details. At 1–3 mm, a fillet is a realistic “eased edge” (the kind a router makes on wood), which is the correct level of detail for interior design presentations. Offsets above 5–10 mm start to read as a design element rather than a material quality. Using the same offset across an entire scene creates visual consistency — pick one value (e.g., 2 mm for all panel edges, 5 mm for leg tops) and apply it globally rather than eyeballing each component.
  • Soften/smooth after every RoundCorner operation, not at export time. SketchUp’s Soften Edges dialog is angle-based: edges shared by faces whose normals differ by less than the threshold angle are softened. After RoundCorner the fillet faces are nearly coplanar (small angle between them), so a threshold of 20–30 degrees hides all the triangulation without hiding intentional sharp corners elsewhere. If you leave softening to the end of the project you may find that later operations (Push/Pull, Move) re-introduce hard triangle edges you missed.
  • Work inside components or groups, not loose geometry. RoundCorner operates on selected raw geometry. If your model is a component and you double-click to enter it before selecting edges, the fillet only affects the geometry inside that component — exactly what you want. If you accidentally run it on loose geometry that is shared between multiple components, SketchUp’s geometry merging will produce unexpected results. Always open the component context (double-click) before selecting and rounding edges.

System Requirements

  • SketchUp version: SketchUp 2017 or later (tested through SketchUp 2026). SketchUp Make 2017 (free, discontinued) also works.
  • Required companion: LibFredo6 — must be installed and on the same version family as RoundCorner. Both are updated together on Sketchucation; install the latest of each.
  • Operating system: Windows 10/11 or macOS 11 (Big Sur) or later. No known Linux support (SketchUp itself is Windows/Mac only).
  • Cost: RoundCorner requires a paid perpetual license — buy at sketchucation.com. LibFredo6 is free. A free Sketchucation account is required to download.
  • Installation method: .rbz via SketchUp Extension Manager. Manual copy to Plugins folder also works but is not recommended (version tracking is harder).

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Nguyen Huu Khanh

Architect turned developer