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FreeCAD AI Modeling Guide

Building from scratch

Leave FreeCAD open, tell the AI the dimensions, and it draws the sketch and stacks Pads, Pockets and fillets in order to build a Body. It replaces picking a sketch plane with the mouse and adding constraints one at a time. The result is an ordinary FreeCAD PartDesign model — turn the AI off and you can still open the features in the tree and edit them by hand.

Things you can ask for

Section titled “Things you can ask for”
Say this What you get
“Make a 100×60×10 plate” A Body with an XY-plane rectangle sketch + a 10 mm Pad
“Ø6.6 through holes 10 mm in from each corner” A four-circle sketch + a through Pocket. The diameter becomes the parameter hole_d
“A Ø40 cylinder 30 mm tall with a Ø20 boss 5 mm on top” Two Pads stacked, overlapping, in one Body
“Cut a groove by revolving around the centre axis” A revolved cut (Groove) — the AI picks the section polygon and the axis
“Revolve this section 360°” A Revolution
“R3 fillet on the outer edges, 0.5 chamfer at the hole mouths” Fillet and Chamfer, with edges selected by radius and position
“Ø44.5 male thread, pitch 2, length 8” A helical cut — one pitch of the root section swept as a helix
“Pull the thickness out as a parameter” An alias appears in the Params spreadsheet and the feature references that expression

A representative prompt

Section titled “A representative prompt”
Say this
Make me a bracket in a new document.
- Base plate 120×80, 8 thick
- Four Ø6.6 through holes, 12 mm in from each corner of the base plate
- A vertical plate on the rear long edge, 60 tall and 8 thick (an L shape)
- A Ø20 through hole in the middle of the vertical plate
- R5 fillets on the outer edges
Pull every dimension out as a parameter, and show me an isometric screenshot when you're done.

Check the screenshot and the tree to confirm you got what you asked for. Dimensions you dislike can be changed as numbers in the Params spreadsheet, or you can just tell the AI “make wall_h 80”.

What parametric means here

Section titled “What parametric means here”

Every sketch the AI builds has zero remaining degrees of freedom, and the dimensions reference spreadsheet aliases. Which means:

  • Double-click PadBase in the tree and change the length by hand, and the features below follow.
  • Change hole_d from 6.6 to 9 in the Params sheet and all four holes grow at once.
  • The sketches the AI creates are hidden in the tree (Visibility=False) but are otherwise ordinary sketches. You can open them and edit the constraints.

Things to know

Section titled “Things to know”
  • You have to ask it to save. The AI does not write the file until you say “save it”. Give it the name and the path.
  • Give it the datum plane and direction and it won’t ask back. Something like “base on XY, up is +Z”. If you leave it out, the AI decides and tells you what it decided.
  • Break long jobs up. Put dozens of features in one sentence and, when one of them fails midway, it is hard to find where it stopped. Saying it in three passes — mass, then holes, then finishing (fillets and chamfers) — is safer.
  • A failed feature stays in the document. When the AI says “stopped at PocketCenter”, tell it the cause (the sketch is outside the shape, say) and have it delete and rebuild.
  • The AI reports whether volume went up or down for each feature. If you cut a hole and the volume did not drop, the Pocket never met any material.
Section titled “Related exercises”

What runs behind the scenes

Section titled “What runs behind the scenes”
Tool What it does
build_features Stacks a list of sketches + Pad/Pocket/Groove/Revolution/Fillet/Chamfer/helix into a Body in order, verifying each feature; params go into a Spreadsheet
tracked_recompute · get_screenshot Confirms the recompute result; PNGs from 12 directions including iso and front
save_document Saves only when asked