FreeCAD Sketcher by Hand vs Claude AI: Sketch and Pad Your First Part | FreeCAD + Claude Course 2

FreeCAD Sketcher tutorial: sketch and pad your first part in Part Design, by hand and then by Claude AI, measured by FreeCAD itself. Watch the course in order:    • FreeCAD + Claude Course (Start Here, in or...   What we found: Claude's FreeCAD hook stands the right way up (in the SolidCraft course, almost the same message built it upside down), and every number matches the hand-made one. But its sketch has no sizes pinned: 16 degrees of freedom, and a dragged corner makes the back plate lean over. Ask Claude for the sizes, then open the sketch and check it says Fully constrained. Tested: FreeCAD 1.1.4, freecad-mcp 0.1.28, Claude Code 2.1.308 with Claude Sonnet 5.5, Linux (Docker), 29 Oct 2026. Setup (the add-on, uv, the plug line): lesson 1,    • How to Connect Claude to FreeCAD (MCP Setu...   By hand (FreeCAD 1.1.4): 1. File, New Document. Workbench list: Part Design. New Body. 2. New Sketch, pick XZ-plane in Select attachment, OK. (XY lies flat, XZ stands up facing you, YZ sideways.) 3. Polyline: click the origin, then each corner roughly in place: right, up, left, down, left, up, left, and back to the first point. 1.1.4's Polyline has no typed lengths. 4. Press D (Dimension), click a line, click beside it, type the size, Enter. Six sizes: the bottom 25, the lip's outer side 10, the lip's top 5, the lip's inner side 5, the back plate's height 60 (from its top corner to the origin), the back plate's top 5. The arm's top line gets none (25 - 5 - 5 = 15). Sketch Edit says Fully constrained. 5. Close. Click the sketch in the Model tree, Pad, Length 20, OK. Key 0 for the isometric view. 6. View, Panels, Python Console. Click the pad in the tree and type: Gui.Selection.getSelection()[0].Shape.Volume b = Gui.Selection.getSelection()[0].Shape.BoundBox; round(b.ZMin, 3), round(b.ZMax, 3) You should get 8500.0 and (0.0, 60.0), with the lip on the right. The message we sent Claude (in a new, empty document): In FreeCAD, sketch this outline on the XZ plane, starting at 0,0: right 25, up 10, left 5, down 5, left 15, up 55, left 5, then back to the start. Extrude it 20 mm. (The SolidCraft course's lesson 2 sent the same with "In SolidCraft". Our second message: "Measure it, and list the steps in its model tree." There it said "timeline".) What we measured (our lab): By hand: 8,500.0 mm³, 25 x 20 x 60, X 0 to 25, Y -20 to 0, Z 0 to 60; 23 constraints (joins, level and upright rules, one corner kept on an axis, six sizes), fully constrained. Claude, run 1: one execute_code call (Python inside FreeCAD): a Part Design body, a sketch attached to the body's XZ plane, eight lines, eight "coincident" constraints only, a pad of 20. Same volume, size, place and steps as ours. Its reply said: "The sketch is closed but has no dimensional constraints, only coincident points." It offered to add them. Claude, run 2 (a fresh session): the same. A no-AI replay of run 1's logged calls in a fresh FreeCAD: 8,500 mm³, the same eight constraints. Claude's sketch opened in FreeCAD: Under-constrained, 16 degrees of freedom; one drag and the back plate leans over (Ctrl+Z undoes it). In SolidCraft (our earlier lesson): the plug's XZ sketch had its "up" along -Z, so the same outline hung from 0 down to -60. How this was filmed: the real apps in a Linux container, recorded and zoomed onto what is clicked; the by-hand clicks were played by a script at a person's pace; a logging wrapper recorded every message to the plug unchanged; in Claude's session the by-hand document was already open (the viewer's starting state), and Claude worked in a new one; run 1's checks after Claude's turn were filmed on run 1's saved document, opened again with no AI; sped-up parts are marked. The lab (scripts, logs, tests): https://github.com/thestackunderflow/... The same hook in SolidCraft:    • SolidCraft Tutorial for Beginners: Sketch ...   CHAPTERS 0:00 By hand vs Claude: which way up? 0:45 A body and a sketch on the XZ plane 2:00 Polyline, constraints, degrees of freedom: fully constrained 3:58 Pad 20 and check it with two console lines 5:38 The same part by Claude 6:55 Side by side, and what's missing inside 8:20 Your turn Not affiliated with FreeCAD, freecad-mcp, SolidCraft or Anthropic. #FreeCAD #ClaudeAI #MCP Narration: AI-generated voice