Installation

Katydid is not in the workbench list. Check that InitGui.py sits directly in <Mod folder>/Katydid/, not one level deeper (Katydid/Katydid-main/InitGui.py is a common result of unzipping). Check the folder name too, then restart FreeCAD. View  Panels  Report view shows the error if Katydid failed to load.

"No module named PySide6", or Qt errors in the Report view. Katydid needs FreeCAD 1.0 or later with PySide6. Older FreeCAD versions (0.21 and before) use PySide2 and are not supported.

The canvas

I closed the canvas window. Use Katydid  Canvas or the toolbar button, or double-click the Katydid object in the model tree.

Nothing appears in the 3D view. Check that Preview on the canvas toolbar is on, that the components' own previews are on (a darker grey component has its preview switched off), and that the component is not orange or red. Then use FreeCAD’s Fit all (V, F) in the 3D view; the geometry may simply be off-screen.

A component is orange. Usually one of its inputs has no data. Hover over it to see which; wire something in, or use Set value… on the input’s right-click menu to give it a value.

A Solid Difference, Union or Intersection is orange: "The Boolean result is not a valid solid". OpenCascade, FreeCAD’s geometry kernel, sometimes returns a broken solid instead of an error. It happens most when a cutting solid touches the other solid’s seam edges or meets its surface exactly tangentially, for example short cylinders standing exactly on a pipe’s surface at 0°. Katydid passes the result on but marks it. Move or lengthen the cutters slightly so they cross the surface instead of touching it. A Boolean that is flagged valid can still occasionally miss a cutter, so check the volume (Area gives it for faces; FreeCAD’s measuring tools for solids) when it matters.

A component is red. It could not compute. Hover over it for the reason, for example "Radius must be positive" or "A loft needs at least two section curves" (see the tree tutorial for that one).

My wire went away when I connected a second one. Connecting to an input that already has a wire replaces it. Hold Shift while you release to add the wire instead.

Pressing Delete did not delete my FreeCAD object. That is deliberate: while the canvas has the keyboard focus, Delete removes canvas components only. Click in the model tree or the 3D view first to delete document objects.

Dragging feels slow. Heavy previews (hundreds of curved surfaces) take longest to draw. Switch off the previews you do not need (Ctrl+Q) or the whole preview (Preview). Keep the canvas floating: docked, it redraws noticeably slower.

The results differ from Grasshopper. Katydid follows Grasshopper’s data-matching rules as described in Data trees, but they have not been verified against Grasshopper itself. Please report differences on GitHub with both results.

Known limits

Version 0.1 does not yet have:

  • undo and redo on the canvas (FreeCAD’s undo does cover baking);

  • copy and paste of components, groups, clusters, or a radial menu;

  • a Param Viewer, Path Mapper or other tree-editing components;

  • a script component for writing your own components on the canvas;

  • resizing panels with the mouse (their size is saved, but set in code);

  • two-dimensional and angular tolerance stacks, datum shift and datum reference frames;

  • importing Grasshopper .gh / .ghx files.

These are on the roadmap. Suggestions and contributions are welcome: see Contributing.

Reporting a problem

Open an issue with your FreeCAD version (Help  About FreeCAD, then Copy to clipboard), what you did, what you expected and what happened. A small .FCStd file that shows the problem helps most.