Comb Plot¶
In one sentence: Displays a curvature comb on selected edges — spines perpendicular to the curve with length proportional to curvature — for diagnosing B-spline quality.
Third-party addon — installation required
The Curves workbench is not included in FreeCAD. Install it via Tools → Addon Manager → search "Curves" → Install and restart FreeCAD.
Overview¶
Workbench: Curves
Menu: Curves → Comb Plot
Command: ParametricComb
A curvature comb shows the curvature magnitude at every point along a curve as perpendicular spines. Ideal combs are smooth and uniformly spaced; sharp spikes indicate curvature peaks; oscillations indicate an over-controlled B-spline.
Use Comb Plot before using a curve as a surface boundary — oscillating curvature will produce oscillating surface quality.
Reading the comb¶
| Comb appearance | Interpretation |
|---|---|
| Smooth, uniform spines | Well-distributed curvature |
| Large spike | Local curvature peak — check for over-constrained knot |
| Alternating tall/short spines | Oscillating B-spline (too many control points) |
| Flat section (no spines) | Straight segment or inflection point |
See also¶
- Blend Curve — create the smooth blends that produce clean combs
- Zebra Tool — visual continuity check for surfaces
- Curves Workbench — workbench overview