AI CAD prompt: Ribbed bearing mount

Build a native editable bearing flange in a new owned Nora3D document using millimeters. The square base is 80 x 80 x 6, centered on XY, underside Z=0. Add a cylindrical hub of radius 18 from Z=6 to Z=28. Add four rectangular reinforcing ribs from Z=6 to Z=20. East and west ribs occupy X=15..37 and -37..-15 with Y=-2.5..2.5; north and south are the corresponding 90-degree positions. Merge them with the base and hub.

Cut four 6.5 diameter bolt holes at (±28,±28), through the base. Add a coaxial through-hole with radius 8. Cut a larger top recess of radius 11.1, depth 7 measured downwards from Z=28. Verify the recess direction before accepting it: the shoulder must be at Z=21 by default. Keep a real annular shoulder between the recess and smaller hole.

Expose bearing-seat radius 10–12 in 0.1 increments, depth 5–10 in 1 mm increments, and shaft-clearance radius 5–8 in 0.5 increments. All other features remain fixed. Validate every range corner plus default and midpoint: recess radius must exceed shaft radius, hub walls remain present, all four mounting holes stay outside the hub/ribs, and the model remains one connected solid. Check actual regenerated volume, closed consistently oriented STL and strict save/reopen. Radius controls are intentionally labeled as radius; do not call them diameter or suggest a guaranteed press fit. The model is a printable prototype with no established bearing retention or load rating.