# Iterations 11-12
## 11: docs/gantry/WIRING.md — steppers->TMC2209->SKR, steps/mm (belt 80, leadscrew 400), endstops + home
   order (Z,X,Y-up), TMC current, STS3215 serial bus, 24V + buck, safety. Gantry now fully buildable.
## 12: mobile_base.urdf v2 = proper DIFFERENTIAL drive (2 big driven wheels mid + 2 spherical casters) instead
   of 4 fixed wheels. HTTP 200. More realistic + steerable base.
## Next
- Mobile: printable arm-mount plate + lift leadscrew (reuse gantry T8 lesson); controller BOM for the base.
- Gantry: workspace/reach note; assembly hero render.