The five parts of a prompt
The AI reads inside FreeCAD, but it cannot read your mind. What you leave out, it either asks about or assumes. The way to cut down the asking is to put five things in from the start.
1. The subject — which document, which object
Section titled “1. The subject — which document, which object”If only one document is open you can skip it. With two or more, name it. Refer to objects by the Label shown in the tree.
In document bracket_v2, tell me why Sketch003 in the Body is red.2. Dimensions and units — every number
Section titled “2. Dimensions and units — every number”Lengths in mm, angles in degrees. For a plate: width × depth × thickness. For a hole: diameter, count, position (so many mm in from the edge, or a pitch). “About right” gets you a question back.
A 100×60 plate, 5 thick. Four Ø6.6 through holes, 10 in from each corner.3. The datum — which plane, which direction, measured from what
Section titled “3. The datum — which plane, which direction, measured from what”Whether to draw on XY and pad up +Z, which side is the front. When transferring from a drawing, where to put the origin. Leave it out and the AI decides and tells you. Usually it draws on XY and pads upward.
Draw it on XY and pad upward. The origin is the bottom-left corner of the plate.4. The check — what you want shown
Section titled “4. The check — what you want shown”By default the AI shows you the recompute result (no errors) and a screenshot. Say what else you want.
When you're done, show me an iso screenshot, the volume and the sketch degrees of freedom.5. The save — only when you ask
Section titled “5. The save — only when you ask”The AI does not save until you tell it to. Give the full path.
Save it to D:\models\plate.FCStd.All five in one sentence
Section titled “All five in one sentence”In a new document, draw a 100×60 plate 5 thick on XY and pad it upward, then drill four Ø6.6 through holes 10 in from each corner. Put the dimensions in a spreadsheet called Params, and when you're done show me an iso screenshot and the degrees of freedom. Don't save yet.What happens when something is missing
Section titled “What happens when something is missing”| Missing | What the AI does |
|---|---|
| Thickness | Asks, or says “assuming 3 mm” and continues |
| Hole positions | Asks. When transferring from a drawing, measures from the vectors and says so |
| Plane and direction | Draws on XY, pads +Z. If the result looks flipped, say “mirror it about Y” |
| Document name (several open) | Asks which document |
| Material (analysis, printing) | Assumes PLA and says so |
When the AI has assumed something, look for the word “assum” in its answer. If it got it wrong, correct it on the spot.
The thickness is 5, not 3. Do it again.What not to do
Section titled “What not to do”- Ten things in one sentence. Make the plate, drill the holes, add fillets, produce the drawing and check printability all at once, and when something goes wrong in the middle you cannot tell where. Break it into threes and fours.
- Reading out coordinates yourself. When redrawing a STEP or STL, do not copy vertex coordinates out and feed them back in. The AI traces the original directly. “Trace the original section exactly” is enough.
- Asking for round numbers. “Make the radius a clean 33.62” puts it out of line with the original and loses volume. Let it keep the measured value.