SolidCraft Parameters by Hand vs Claude: Named Sizes for Beginners | SolidCraft + Claude Course 3

SolidCraft parameters for beginners: give a 3D part's sizes names, change one number and the whole part updates, by hand and with Claude, measured. The same change on plain numbers is refused, and one Claude run made a mistake that the change grew. Watch the course in order:    • SolidCraft + Claude Course (Start Here, in...   Lesson 1 (connect Claude to SolidCraft):    • How to Connect Claude to SolidCraft: MCP S...   Lesson 2 (the wall hook, by hand vs Claude):    • SolidCraft Tutorial for Beginners: Sketch ...   Tested: SolidCraft 0.26.1, Claude Code 2.1.311 with Claude Sonnet 5.5, Linux (Docker), 29 Oct 2026. Lesson 2 used SolidCraft 0.25.0; this lesson uses 0.26.1, so update first (designs saved in 0.26 don't open in 0.25.1 or older). By hand (written out, so you can follow along): 1. New design (millimetres). Model tab, Parameters. Add parameter: type the name, press Tab twice, type the value, press Enter. Five names (the underscore is Shift and minus, no space): hook_depth 25, thickness 5, lip_height 10, plate_height 60, width 20. OK. 2. New Sketch, XZ in the Browser, Line, click the origin. Point the way each line goes and type a name or a formula instead of a number (the star is times, Shift and 8): right: hook_depth up: lip_height left: thickness down: lip_height - thickness left: hook_depth - 2 * thickness up: plate_height - thickness left: thickness then click the first point, Esc. The dimensions show fx: they come from the names. 3. Finish Sketch, Extrude, Distance: width, OK. 4. Check: right-click Body1, Properties: 8500.00 mm³, 25 x 20 x 60 mm. 5. Work out the change first: hook_depth 40 gives 5 x 60 + 35 x 5 + 5 x 5 = 500 mm², x 20 = 10,000 mm³, 40 x 20 x 60. 6. Parameters, hook_depth: 40, Enter. The hook rebuilds. Properties: 10000.00 mm³, 40 x 20 x 60 mm. The sentence we put in front of the request to Claude: Use named sizes (parameters) plate_height 60, width 20, thickness 5, hook_depth 25, lip_height 10, and write every length and the extrude distance from them. What we measured (our lab): By hand with names: 8,500.0 mm³, then 10,000.0 mm³ and 40 x 20 x 60 after one change. Lesson 2's plain-number hook, d1 (the 25) set to 40: refused, "its constraints would conflict ... the values were not changed". The box still shows 40; the hook stays 25 x 20 x 60. The four lengths across the hook must add up: 5 + 15 + 5 = 25. Writing d5 (the 15) as d1 - 10, then d1 = 40, works: 10,000 mm³. Claude, not asked for names (2 runs): no named sizes. One drew the hook again in a new design (40 x 20 x 60, 10,000); one read "40 deep" as the extrude (25 x 40 x 60, 17,000) and said so. Claude, asked in one sentence (2 runs): five names and a one-number change both times. One run placed the back plate's inner edge at hook_depth - 2 * thickness instead of thickness: 19,500 mm³ instead of 8,500, and 37,500 after the change. The other: 10,000, 40 x 20 x 60. Every run first built the hook hanging below Z 0 (lesson 2's finding), checked, and built it again standing. Proof: two runs' logged tool calls replayed with no AI in a fresh SolidCraft: 10,000 and 37,500 again; our STL checker agrees. In an earlier test of ours, Claude named 0 of 6 sizes when not asked. So: work out your number first, and check the first build in Properties. How this was filmed: the real SolidCraft window in a Linux container, recorded and zoomed. The by-hand clicks and keys were played by a script at a person's pace. Claude Code ran in its own terminal; nobody touched the mouse during its runs. Speed changes are marked on screen. The lab (scripts, logs, tests): https://github.com/thestackunderflow/... Deep dive on resizing a part:    • SolidCraft Tutorial: Make a Part That Resi...   CHAPTERS 0:00 One change, two results 0:37 Named amounts: the recipe card 0:55 Parameters in SolidCraft 1:13 The catch: lengths that depend on each other 1:28 By hand: five names 2:03 Draw the J with names and formulas 3:05 Extrude by width, check 8,500 3:18 Work out 40 first 3:40 Change hook_depth: 10,000 3:55 Plain numbers: refused, and why 4:48 The fix: a formula 5:13 Claude, not asked for names 6:08 Claude, asked in one sentence 6:21 The thick back plate 7:22 Side by side 7:47 Check the first build, your turn 8:24 Recap Not affiliated with or endorsed by SolidCraft (Tangency Labs) or Anthropic. #SolidCraft #ClaudeAI #CAD Narration: AI-generated voice