I've spent a lot of time talking to GrandpaCAD. It's magic when it works, but sometimes it feels like we're speaking different languages. I realized that using the right words, the words actual CAD designers use, makes a huge difference in the output.

If you want a box, say "box". But if you want a specific shape with rounded corners and a hole in the middle, you need to be precise.

I put together this cheat sheet. It's a list of terms that help the AI understand exactly what you want to build.

Primitives (the basics)

These are the starting points for almost any design.

• Cube / Box: A standard six-sided block.
• Sphere: A perfect ball.
• Cylinder: A tube. Remember to specify if you want it hollow (a pipe) or solid (a rod).
• Cone: Tapers from a circle to a point.
• Torus: A donut shape.

Transformations (moving stuff)

• Translate: Move an object along the X, Y, or Z axis.
• Rotate: Spin an object around an axis.
• Scale: Resize an object. You can scale uniformly or just along one axis (stretching).
• Mirror: Create a reflection of the object.

Boolean operations (combining)

This is how you make complex shapes from simple ones.

• Union: Fuse two shapes together into one solid object.
• Difference: Subtract one shape from another. Use this to make holes or cutouts.
• Intersection: Keep only the part where two shapes overlap.

Features (details)

• Chamfer: A flat cut on an edge, usually at 45 degrees. Good for making things easier to insert or hold.
• Fillet: A rounded edge. Reduces stress concentrations and looks nice.
• Shell: Hollow out a solid object, leaving walls of a specific thickness.
• Extrude: Take a 2D shape (like a circle or square) and pull it into 3D.

Positioning

• Origin: The center of the workspace (0,0,0).
• X-axis: Left and Right.
• Y-axis: Forward and Backward.
• Z-axis: Up and Down.

Using these terms in your prompts acts like a shortcut. Instead of describing a "round corner thing", ask for a "10mm fillet". The AI knows what that means.

Bookmark this. It comes in handy when you're trying to get that one specific geometry just right.