=================== Frame and Extrusion =================== The structural backbone of the RoboFlock is split between two parts that work together: a pair of 4080 aluminum extrusions running along the sides of the robot, and a 3D-printed main chassis frame that hangs above and between them. This split keeps the high-load mounting interfaces (motor brackets, suspension brackets) on rigid metal extrusion, while the printed frame carries the lower loads associated with the body, battery compartment, and hull. Side Rails - 4080 Extrusion ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Each side of the robot has a single length of 4080 T-slot aluminum extrusion running front-to-back. The profile is mounted with the **40 mm face down**, so the rail stands 80 mm tall. Each rail provides two structural functions: - **Inner rail** (the face pointing toward the centerline of the robot) - the rocker beam bracket for that side clamps around this rail, anchored with 4 bolts (2 into the top T-slot, 2 into the bottom). This provides the mounting interface for the printed main chassis frame, which sits between both extrusions - **Lower rail** - (the face pointing downward) - the two motor brackets for that side bolt to this rail, 3 bolts each, into the T-slot. See ``RV1-CHS-FRM-001`` in the :doc:`Parts Catalog <../parts_catalog>` for sourcing and exact length. .. note:: Length, fastener size, and T-nut style are still TBD in the catalog - confirm with assembly hardware once the first set is sourced. Main Chassis Frame ^^^^^^^^^^^^^^^^^^ The main chassis frame (``RV1-CHS-001``) is the largest single 3D-printed part on the robot. It serves three roles: #. Mounts the body, battery compartment, and hull (top + bottom screw interfaces). #. Provides the **suspension pivot ears** - two L-shaped projections that drop down. Each ear contains a press-fit bearing whose inner race rides on the outer diameter of the suspension's inboard hollow rod stub. This pair of bearings defines the per-side suspension pivot axis. #. Anchors the rocker differential arm - at the front of the frame, a shoulder bolt threads upward into the frame, providing a vertical pivot for ``RV1-SUS-001``. .. note:: The "ears" carry the entire suspended weight of the robot through their pressed bearings. Inspect for layer delamination or insert pull-out before each test session and re-print if any cracking is visible around the bearing seats. Load Path Summary ^^^^^^^^^^^^^^^^^ Vertical load travels: .. code-block:: text Hull, electronics, battery │ ▼ Main chassis frame │ ▼ Bearings in frame ears │ ▼ Hollow rod stubs │ ▼ 12 mm pivot hubs │ ▼ Rocker beam brackets │ ▼ 4080 extrusions │ ▼ Motor brackets ───► Motors ───► Wheels ───► Ground The differential arm and its pushrods do **not** carry vertical load directly - they constrain anti-symmetric pivot motion between the two sides, and absorb only the differential force needed to enforce that constraint. .. seealso:: :doc:`Drive System ` What bolts to the inner rails of the extrusions :doc:`Suspension ` What hangs from the ears of the main frame :doc:`Parts Catalog <../parts_catalog>` Files and BOM for every part referenced here