single plate chassis:

Designed with a flat base so that 3D printing is straightforward and with the following design elements:

• notched sides and through slots for 2 or 4 motor fixing points;
• fixed raised mounting points for 6mm M2 self tap screws to suit Raspberry Pi2, 3 and 4 SBC placement;
• raised edge bar for fixing an OLED 'case';
• through holes for M3 pan head screws with an underside hex 'cut' opening for M3 nuts to allow the following to be fixed onto the chassis:
  • 3D printed 'frames' that hold 1 or 2 L298N motor controllers, mountable in several possible positions
  • pairs of 3D printed mounting clips for both 22mm and 32mm diameter rechargeable battery banks, each mountable in two possible positions
  • various optional mounting 'cradles' so that different system controllers can be used, e.g. a Raspberry Pi 3A or PiZero SBC or a small microcontroller.
• it should be noted that in a couple of locations where motors are 'hung', thin/half M3 nuts should be used in the underside hex openings so that they are completely flush with the underside of the chassis plate.

motor mounting tabs:

Pairs of these 3D printed 'tabs' (shown in dark pink in the images on the right) allow 2 or 4 of the commonly available geared drive motor (often called a YG2900) to be secured to the underside of the chassis plate. When only two motors are used, these can be positioned at either the front or the rear for a 2WD option.

The inner motor fixing tabs are a push fit through a slot in the chassis and the outer tabs are held in a small notch rather than another slot. Each motor is held in place with a pair of M3 pan head screws (at least 25mm long) and M3 nuts.

Slide switch spacer:

This 3D printed 'spacer' is used to create additional space between the set of four slide switches and the PCB top surafce (in an attempt!) to avoid excess solder 'wicking' up to the slde switch and creating short circuits to its metal casing.

L298N motor controller mounting frame:

This 3D printed frame (shown in green in the image on the right) allows an L298N motor controller (shown in blue in the image on the right) to be fixed, in a vertical orientation, in several different positions on the upper side of the chassis plate, depending upon the build requirement, e.g. a pair can be installed to mount two L298N controllers for a 4WD mecanum build

A pair of 6mm long M3 pan head screws, that screw into M3 nuts secured on the underside of the chassis in hexagonal 'cut' openings, are used to bolt a frame to the chassis plate and four 6mm M2 self tap screws hold the L298N to the frame.

fixed ultrasonic sensor mount:

A 3D printed holder (shown in green in the images on the right) fixes to the servo opening on the chassis plate using 6mm M2 self tap screws to provide a fixed mounting point (i.e. when a servo is not installed).

The ultrasonic sensor wired assembly is simply inserted into the 3D printed holder as shown in the second image on the right.

servo mounted ultrasonic sensor:

A 3D printed holder (shown in green in the images on the right) fixes to a SG90 servo that is installed in the opening on the chassis plate using 6mm M2 self tap screws.

The 3D printed holder has a recess where the standard 'single arm' servo horn is inserted, so that the combined holder and horn can be screwed onto the splined drive shaft of the servo using the small M2 screw supplied with the servo.

The ultrasonic sensor wired assembly is simply inserted into the 3D printed holder as shown in the second image on the right.

fixed mount for ultrasonic sensor and Raspberry Pi camera:

A 3D printed holder (shown in green in the images on the right) fixes to the servo opening on the chassis plate using 6mm M2 self tap screws to provide a fixed mounting point (i.e. when a servo is not installed).

The ultrasonic sensor wired assembly is simply inserted into the front slot of the 3D printed assembly and the Raspberry Pi camera is inserted into the higher second slot as shown in the second image on the right.

servo mounted ultrasonic sensor and USB camera mount:

A 3D printed holder (shown in green in the images on the right) fixes to a SG90 servo that is installed in the opening on the chassis plate using 6mm M2 self tap screws.

The 3D printed holder has a recess where the standard 'single arm' servo horn is inserted, so that the combined holder and horn can be screwed onto the splined drive shaft of the servo using the small M2 screw supplied with the servo.

The ultrasonic sensor wired assembly is inserted into the front section of the 3D printed holder and a USB camera with a spring clip can be affixed to the top section of the 3D printed holder as shown in the second image on the right.

128x64 OLED mount assembly:

A 2-piece custom 3D printed holder for a 128x64 px OLED is used to mount the complete display assembly to the chassis plate onto the raised block on the right-hand side of the plate using two 16mm long M2 self tap screws (shown in dark blue in the image on the right). The two halves of the 3D printed holder are held together with four 6mm M2 self tap screws.

Two things to note:

1. Some of the OLEDs available from various online sources have their VCC and GND pins swapped around, so care needs to be taken with the wiring.
2. The main 3D design (OLED1) for the 2-piece holder is for the commonly available 128x64 pixel OLED that is 27.3 mm wide and 27.8mm high. An alternative (almost identical) design (OLED2) for another commonly available OLED that is just 24.7mm wide and 27.0mm high has also been developed.

32mm 5000mAh 5V/2A battery bank mounting clips:

A pair of custom 3D printed clips (shown in pinkish mauve in the images on the right), that can be inserted and bolted to the chassis plate in two optional positions (transverse and to one side), allow a quite large battery bank with an outside diameter of 32mm to be fitted to the chassis and used to power both the system controller and the drive motors.

21mm 3350mAh 5V/1A battery bank mounting clips:

A pair of custom 3D printed clips (shown in dark pink in the images on the right), that can be inserted and bolted to the chassis plate in two optional positions (transverse and to one side), allow a slim battery bank with an outside diameter of 21mm to be fitted to the chassis and used to power both the system controller and the drive motors.

marble castor mount:

The 3D printed 'castor' is used to support either the front or back of the robot when just two drive motors are used for a back or front 2WD option, as shown in the images on the right.

The 3D printed item is secured to the underside of the chassis plate with 8mm M3 screws that connect to M3 nuts inserted into hex shaped cut-outs on the top side of the plate.

A glass marble is a (tight!) fit into the end of the castor print, where it can rotate freely, and depending upon the floor surface even if the marble sometimes 'sticks', it still provides a relatively low friction contact with the floor.

Use of the Raspberry Pi Maker PCB:

The Raspberry Pi Maker PCB's main purpose is an educational one, allowing a user to explore how a Raspberry Pi single board computer (SBC) can control a wide range of individual components, i.e. drive motors, sensors, etc. It then enables a user to build up their own 'library' of tried and tested software and methods that they could combine and use in further projects of their own. However the PCB assembly itself can be used in more complete projects and the Flexible Chassis Design allows 2WD and 4WD robots to be built that are controlled and managed by a Raspberry Pi.

The 3D printed chassis plate has mounting points for Raspberry Pi's 3A, 3B and 4B that use 6mm M2 self tap screws, as illustrated in the first three images on the right where the grey rectangular object is the 'space envelope' of the assembled Maker PCB which fits directly onto the Pi's GPIO pins.

The only additional components needed for these configurations are a pair of hexagonal spacers (shown below and in dark green in the images on the right) that secure the overhanging portion of the PCB to the chassis plate.

The 4th and 5th images on the right show that a Raspberry PiZero can also be used to control a Flexible Chassis Design robot but this requires another, separate, 3D printed 'mount' that screws to the chassis plate (shown below and in blue in the images on the right)) and this then aligns with the outer pair of the PiZero mounting holes.

The 5th image on the right also shows that, with another two custom 3D printed components (shown below and in brown in the image on the right), a 3 port USB + ethernet adaptor can be secured to the chassis plate which overcomes the lack of multiple USB ports on a PiZero.

Use of the ESP32 Maker PCB:

Like all the Maker PCBs, the ESP32 Maker PCB's main purpose is an educational one, allowing a user to explore how a ESP32 microcontroller can control a wide range of individual components, i.e. drive motors, sensors, etc. It then enables a user to build up their own 'library' of tried and tested software and methods that they could combine and use in further projects of their own. However the PCB assembly itself can be used in more complete projects and the Flexible Chassis Design allows 2WD and 4WD robots to be built that are controlled and managed by a ESP32.

Using three additional 3D printed components (shown below and in pink in the images on the right) the Maker PCB's assembled PCB with its 'underslung' ESP32 can be attached to the chassis plate as shown right.

Use of the Pico Maker PCB:

As with the previous Maker PCBs, the Pico Maker PCB's main purpose is an educational one, allowing a user to explore how a Raspberry Pi Pico microcontroller can control a wide range of individual components, i.e. drive motors, sensors, etc. It then enables a user to build up their own 'library' of tried and tested software and methods that they could combine and use in further projects of their own. However the PCB assembly itself can be used in more complete projects and the Flexible Chassis Design allows 2WD and 4WD robots to be built that are controlled and managed by a Pico.

Using two additional 3D printed components (shown below and in pink in the images on the right) the Maker PCB's assembled PCB with its 'underslung' Pico can be attached to the chassis plate as shown right.

Use of the custom 'mega-flex' PCB:

Instead of 're-using' a Maker PCB assembled PCB, a custom robot-specific PCB  is being designed (more detailed information here) that can be attached to any of the Raspberry Pi SBCs as well as the ESP32 and Raspberry Pi Pico microcontrollers.

This PCB can either be inserted into any of the Raspberry Pi SBCs in a similar way to the RPi Maker PCB shown above, or it can use the 3D printed mounts shown left to directly attach the PCB to the 3D printed chassis plate with the microcontrollers underslung from the PCB as illustrated in the images on the right with the mounts shown in dark pink.