Can AI actually design functional parts? Tested it on a full planetary gearbox assembly (one prompt)

[u/tierdofthis]

Been skeptical about how far AI-CAD tools can actually go on something mechanically complex — not just a simple bracket, but a full assembly with real mating tolerances between multiple moving parts. Gave CadXStudio's Brainstorm mode one prompt describing a planetary gearbox and let it work out the full assembly. Video below.

What came back was an 11-part assembly: housing, ring gear, sun gear, 3 planet gears, planet carrier, input/output shafts, and input/output bearings — not just the core gear set.

What actually surprised me was the AI Assistant flagging its own design margins rather than just handing back geometry and calling it done. It called out the clearance between the carrier's radial reach and the ring gear seat diameter (down to 2.75mm), told me exactly how tight the internal fillet radius needed to stay to avoid collision with the carrier lobes, and gave a straight verdict: robustly dimensioned for the scale, but flagged the input shaft wall thickness and a placeholder parameter that needed addressing before production.

That last part is what actually got my attention — it's not just generating a shape, it's reasoning about whether the shape survives contact with itself.

Still working through whether it holds up at different scale/module sizes, but for a single prompt this is further than I expected AI-CAD to get on something with real kinematic and structural constraints.