A narrower body around the leg mechanism#

Much of the recent work has gone into modeling the chassis and changing how the legs fit around it. The September 10 assembly explored a wide body with three electronics boards. On September 17, the chassis was narrowed from 103 mm to 51.2 mm, using the nominal PCB width of the selected 1.9-inch display as the reference. These dimensions describe the chassis envelope; the legs and outer shell extend beyond it.

Side view of the September 20 CAD assembly, with exposed red leg links, black servo housings and a pale outer shell.

September 20 assembly view. The measurements below belong to the dated chassis and cable-routing revisions, before some of the later shell changes.

Moving the sides while preserving the interfaces#

Each side assembly moved inward 25.9 mm. The leg meshes, bearing bores, servo geometry and link lengths stayed unchanged in this width revision. The top plate, bottom plate, front carrier and rear cover were rebuilt around their translated interfaces. Later leg changes have their own compact-leg record.

Feature	Earlier layout	September 17 revision
Chassis outer width	103 mm	51.2 mm
Side assemblies	Wide-body positions	Each moved inward 25.9 mm
Rear cover	Earlier wide cover	47.2 mm wide, maintaining a 2 mm inset on each side
Plate thickness	3 mm nominal	Retained; existing top support-contact regions remain 3.2 mm
Q6A board and tray	Part of the wide packaging study	Retired from this narrow layout and retained as a hidden design variant
P4 and PCA9685 models	Existing board geometry and positions	Retained for further mounting and clearance work

Top detail of the narrow chassis, showing the central plate between the paired servo assemblies.

September 17 CAD detail. The narrowed center spans connect the original side interfaces. The view is cropped at the ends; it is not a complete robot outline.

The old center-strip electronics posts and partial mounting holes were removed or closed. Retiring the Q6A’s wide-body fit is a mechanical decision in this revision, not a record of deploying or removing an onboard operating system. The narrower body still needs a coherent board-mounting and cable layout.

Measuring board clearance during shoulder rotation#

The follow-up audit tested the four Part_003 housings against the P4 and PCA9685 models in the narrow chassis. It found the following conservative clearance bounds over the tested rotations:

Housing pair	Board model	Tested rotation relative to neutral	Conservative clearance
Rear left / right	ESP32-P4	About 19° inward to 125° outward	At least 1.970 / 1.967 mm
Front left / right	PCA9685	13.01° inward to 140° outward	At least 0.788 mm on each side

The bounds use the box enclosing each board and its modeled components. The separate fixed-chassis check sampled 308 shoulder poses, with no intersection above its 0.01 mm³ threshold. Further inward rotation did reach the boards: approximately 33° at the rear and 22.3° at the front in that model. Those contact estimates are geometric findings, not calibrated servo stops.

The submillimeter clearance near the PCA9685 matters when routing wires and allowing for connectors and print tolerances. This audit covered housings, boards and fixed chassis parts. It did not establish clearance for the moving links, flexible cables or the evolving shell as a complete assembly.

Moving the camera cable below the face#

On September 18, the front panel’s old top-center cable recess was closed and a new recess cut into its bottom edge. Simply mirroring the old opening still intersected the wider cable tail in the preview, so the inner profile changed.

Cable opening	Earlier profile	Revised bottom-edge profile
Position	Top center	Bottom center
Mouth width	22.35768 mm	Retained
Inner flat	Earlier narrower profile	17 mm
Depth	4 mm	4.8 mm
Two central ventilation slots	21 mm high	18.2 mm high, leaving a 2 mm bridge above the recess
Outer ventilation slots	21 mm high	Retained

The front face, 3 mm central wall, mounting holes and bearing interfaces were preserved. The saved-panel check found one connected solid and no overlap with the modeled cable preview, bottom cover or LCD carrier. Actual cable bending and routing still need a physical check.

What this revision establishes#

The chassis work provides a narrower saved assembly, measured board-clearance evidence and a cable opening fitted to the current preview. It does not yet establish a fully mounted, wired or load-tested robot. The next checks belong to the chosen combination of chassis, compact legs and shell, since those parts have continued to change.

Read the companion updates on compact legs and horn fit and shell development. The September 10 body post preserves the earlier wide layout and its electronics options.

Design records#

These are the original dated records, with local workspace prefixes shortened. Their reported geometry checks were reviewed for this article, not rerun.