Flexible chassis 2WD & 4WD robot

A set of printed components to build 2WD or 4WD robots that can be controlled and managed by any of the Raspberry Pi single board computers (SBCs), a Raspberry Pi Pico microcontroller or an ESP32 microcontroller - where the use of mecanum wheels with custom adaptors for 4WD designs managed by a Raspberry Pi is also now an option.

Detailed descriptions of all aspects of this evolving project are at this link with additional information on the mecanum build option at this link .

The main, single plate 3D printed chassis is designed to allow a standard set of drive, sensor and other components to be assembled in a number of different arrangements to allow different build configurations. It has also been designed to allow individual customisation with Lego blocks and/or card cut-outs that insert into custom 3D printed Lego-compatible blocks (the files for the LEGO-compatible blocks for card cut-outs are available here ).

All the components use 1.75mm PLA and a layer height of 0.15mm with print details for each component produced on an i3 Mk3 shown in the table below.

Updates :

- update May'25 to include a spacer to create space between the 4 slide switches and the PCB top surface to minimise the possibility of solder wicking up and creating short circuits to the switch metal casing - update May'25 to the main chassis plate to support 4WD mecanum builds with some further design tweaks and the addition of embedded version text - update May'25 to update the L298N cradle and to provide a pair of cradles in the .stl file - main chassis plate updated 17th Sept'21 to correct servo and ON/OFF rocker switch cut-outs

component file name/description needs support (Y/N) brim (mm) filament length (m) print time (i3 Mk3)

mega-flex_chassis_plate25-mechanum_repaired.stl: main chassis plate with Lego-compatible studs on the top surface (updated May'25) N 10 15.90 5h 19m

mecanum_wheel_adaptor05_roty180.stl: custom adaptor for connecting a mecanum wheel to the geared drive motor axle N 3 0.75 36m

4x_motor_fixing_tab02.stl: tabs that insert into the chassis plate to secure the drive motors N 3 1.36 31m

slide_switchx4_spacer01.stl : slide switch spacer N 0 0.11 4m

2x_L298N_vcradleExHi_s-lugs02_roty90.stl : vertical fixing mount for a L298N motor controller N 0 2.41 1h 3m

H C-SR04_transverse_fixed_plate01.stl : fixed ultrasonic sensor mount N 0 0.6 20m

HC-SR04_servo_holder02.stl : servo mounted ultrasonic sensor N 0 0.81 25m

HC-SR04_Pi-cam__transverse_fixed_plate05.stl : fixed mount for ultrasonic sensor and Raspberry Pi camera N 0 1.46 1h 0m

HC-SR04+camera_servo_arm09.stl : servo mounted ultrasonic sensor and USB camera mount N 5 2.35 1h 35m

OLED1_flat08-front+back.stl : 128x64 OLED 2pc mount assembly for the 27.3 mm wide and 27.8mm high OLED N 0 2.64 1h 15m

OLED2_flat05-front+back.stl : 128x64 OLED 2pc mount assembly for the 24.7mm wide and 27.0mm high OLED N 0 2.77 1h 16m

32mm_top_open__left-right_bat_holder02.stl : 32mm 5000mAh 5V/2A battery bank mounting clips Y 0 2.21 52m

21mm_top_open__left-right_bat_holder01.stl : 21mm 3350mAh 5V/1A battery bank mounting clips N 0 1.25 33m

stretched_40mm_caster_loose03.stl : front or rear castor that holds a marble ball N 5 2.55 1h 34m

mega-flex_RPi_maker_kit_2x_spacer02.stl: two hexagonal spacers that secure the overhanging portion of the RPi Maker Kit PCB to the chassis plate. N 5 0.63 27m

PiZero_mount01.stl : PiZero 'mount' that screws to the chassis plate and this then aligns with the outer pair of the PiZero mounting holes. N 0 0.55 19m

mega-flex_USB_adaptor_holders_left01+right01.stl : mounts to secure a 3 port USB + ethernet adaptor to the chassis plate which overcomes the lack of multiple USB ports on a PiZero N 0 1.65 42m

ESP32_side_leg01.stl : ‘legs’ that attach one side of the ESP32 Maker Kit PCB to a separate mount (see below) that attaches to the chassis plate N 0 0.69 26m

ESP32_side_leg_mount01.stl : chassis plate mount for the side 'legs' refrenced above N 0 0.37 16m

mega-flex_ESP32_maker_kit_centre_leg01.stl : ' leg' that attaches the other side of the Pico Maker Kit PCB to the chassis plate N 0 0.61 18m

Pico_mount01.stl : leg mount for attaching one side of the Pico Maker Kit PCB to the chassis plate N 0 0.89 39m

Pico_side_leg01.stl : leg mount for attaching the other side of the Pico Maker Kit PCB to the chassis plate N 0 0.61 18m

mega-flex_PCB_mounts01-left+right.stl : pair of mounts for the custom PCB that can connect any of the system controller options N 0 1.82 59m