How to build a RockyBorg kit

Here you'll find the instructions on how to build a RockyBorg kit from PiBorg. Before you embark on this journey of makery goodness, we recommend you set up your Raspberry Pi ready for being placed in the build. Follow the instructions from our Software Install Guide to get ready to build.

Once your Pi is ready to go, start following the steps below:

What's in the kit:

• Two 6V motors with pre-soldered wires
• Two white spoked wheels
• One foam wheel
• Two wheel brackets
  
• One pre-soldered battery clip and on/off toggle switch
• One MG-996R servo
• One metal servo horn
  
• One 8xAAA battery holder (batteries not included)
• One motor controller
  
• Two brass hubs
• Four grub screws
• Two M4x6mm screws
• One M4x45mm screw
• One M4 metal nut
• Ten M3x30mm standoffs
  
• Two M3x25mm screws
  
• Eight M3x12mm screws
• Eleven M3x8mm screws
  
• Four M3 metal nuts
• Twelve M3 nuts
  
• One M3 spring washer
• Four M2.5x6mm standoffs
• Eight M2.5 nylon nuts
  
• Four M2x6mm countersink screws
• Two M2x8mm screws
• Four 2mm washers
• Two M2 nuts
  
• One 2mm allen key
  
• Five pieces of 5mm perspex: One truck, one spacer and three servo mounts.
• Six pieces of 3mm perspex: One top chassis plate, one lower chassis plate, one rear chassis plate, one camera mount and two identical side chassis plates.
  

Required extras:

• A Raspberry Pi (either a Zero W or 3B+)
• An SD card with Raspbian pre-installed
• 8xAAA batteries (rechargeable preferably)
  

Optional extras:

• A Raspberry Pi camera
• A Raspberry Pi Zero camera cable (if using a Zero W)

Tools you will need:

• Flat bladed screw driver
• Phillips screw driver
  
• 5.5mm ring spanner or socket driver
• 7mm open spanner
  
• A piece of card roughly the thickness of a credit card (two business cards works)
• Two rubber bands
  

Assembly Steps:

Overview of steps, you can click on a step to skip to it:

1. Truck assembly
2. Attaching motors to the truck
3. Attaching the servo horn to the truck
4. Fitting the hubs and wheels to the motors
5. Adding the Raspberry Pi mounts to the chassis
   
6. Mounting the servo
7. Assembling the camera mount
8. Adding the camera mount to the left chassis plate
   
9. Joining the left and right chassis plates
   
10. Adding the lower chassis plate
11. Fitting the rear chassis plate
12. Mounting the on/off switch
13. Fitting and calibrating the truck
14. Adding the front wheel
15. Guiding the wires
    
16. Mounting the Raspberry Pi
17. Wiring up and mounting the motor controller
    
18. Installing the battery pack
19. Adding the top chassis plate

Step 1: Truck assembly

For this step you will need:

• The triangular 5mm perspex truck
• Two motor brackets
• Four M3x12mm bolts
• Four M3 metal locking nuts
• A flat headed screw driver
• A phillips head screw driver
• A 5.5mm ring spanner or driver
  

Parts needed for Step 1

Each motor bracket has screw holes in each of the two faces, one has five holes and one has seven holes.

Using the face with five holes and a flat head screwdriver, attach the left bracket to the bottom left pair of holes in the truck using two M3x12mm bolts and two M3 nuts.  The bracket will only fit in one orientation, so make sure your finished left bracket looks like the image below. (You may need to use your 5.5mm ring spanner at this point to hold the nut whilst you tighten the bolt).

Left bracket attached to the truck

Similarly attach the other bracket to the right hand side of the truck using the remaining pair of M3x12mm bolts and M3 nuts.

Both brackets attached to the truck

Step 2: Attaching the motors to the truck

For this step you will need:

• Two P20UK6 motors
• Four countersink M2 screws
• Flat head screwdriver

Each motor needs to be attached to a bracket. Slide the motor's drive shaft through the largest hole in the bracket side with seven holes. The motor casing should sit over the lower part of the truck with the driveshaft pointing outwards. Align the two holes in each motor with the two smallest holes either side of the driveshaft hole.

Using two M2 countersink screws, screw the motor to the bracket. Take care to align the screws correctly before tightening to avoid cross threading. This step is quite fiddly so you might need to ask for an extra pair of hands to help hold the motor in position.

The first motor screwed into position

Repeat with the second motor and two remaining screws on the opposite bracket.

Both motors mounted onto the truck.

Step 3: Attaching the servo horn to the truck

Parts you'll need for this step:

• Metal servo horn
  
• Four M3x8mm cheese head screws

The servo horn and the four screws

The servo horn needs to go on the same side as the motors and brackets with the flange pointing outwards as shown in the image above. Screw the horn into place with the four M3x8mm screws.

Screwing the servo horn onto the truck

All four screws in the servo horn

Step 4: Fitting the hubs and wheels to the motors

For this step you will need:

• Two brass hubs
• Four grub screws
• Two M4x6mm cross head screws
• Two spoked wheels
• One 2mm allen key
  
• A credit card or two business cards to space hubs

Each hub needs to be attached to the drive shaft of one of the motors. Look at the drive shaft of one of the motors and you'll notice that there is a flat side to the shaft. This will be where one of our grub screws will grip when we tighten it.

The flat side of the driveshaft is facing upwards in this image.

Taking the first grub screw, either add two grubs screws or loosen off the grub screws so that they grip the driveshaft, but allow you to slide the hub up and down.

The hubs need to be tightened the correct distance to the bracket. Too close and the wheels will rub against the truck and bracket, too far and the wheels will fall off.

Using a plastic card or two business cards sandwiched together as a spacer, move the hub on the shaft until the card is just pinched between the hub and the bracket screw. The following images give you an indication of the incorrect way to space your hub, and the last one shows the correct spacing using a card.

Hub is too close to the bracket

Hub is too far from the bracket

Hub is correctly spaced using a credit card or two business cards to space it

Tighten up the grub screws and remove the card being used for spacing.

Repeat with the other motor, hub and pair of grub screws.

Add a wheel to the hex end of each hub and using an M4x6mm screw, screw into the hub.

Screw the wheel onto the hex hub

Finally thread the motor wires through the large hole in the middle truck.

The finished truck with wheels and threaded wires

Step 5: Adding the Raspberry Pi Mounts to the chassis

For this step you will need:

• One of the two identical chassis plates
• Two M3x30mm nylon standoffs
• Two M3 nylon nuts,
• Four M2.5x6mm standoffs
• Four M2.5 nylon nuts

Depending on which Raspberry Pi you've chosen to go in your RockyBorg, at this point the four M2.5x6mm standoffs need to be placed differently.

Before placing the M2.5x6mm standoffs, make sure the chassis plate is oriented as in the picture below with the large hole towards the right hand side of the plate. For each type of Pi footprint there is a slightly different arrangement of the standoffs.

The parts needed for step 5

For the Raspberry Pi 3 style footprint:

Take the four M2.5x6mm standoffs and the four M2.5 nylon nuts and screw them into the chassis plate. For the Pi 3 ensure these are the four holes around the large hole which almost form a square.

Positioning of posts for a Raspberry Pi 3.

For the Raspberry Pi Zero style footprint:

Take the four M2.5x6mm standoffs and the four M2.5 nylon nuts and screw them into the chassis plate. For the Pi Zero ensure these are the four holes towards the top of the plate which match the footprint of your Pi Zero. Imagine your Pi in place, and the top half of the large hole will be obscured by the Pi.

Positioning of posts for a Raspberry Pi Zero.

For both types of Pi

From now on we will refer to this plate as the left chassis plate.

Turn over the left chassis plate. Take the M3x30mm posts and M3 nuts and screw them into the two holes at the top of the chassis plate, one behind the thin slot and one above the large hole (the positioning of the nuts on the side with the long standoffs will depend on your choice of Pi).

The long standoffs in position on the Pi.

Flipped back over to the short standoff side so you can see the nuts

Step 6: Mounting the servo

For this step you will need:

• One MG-996R servo
• Three 5mm perspex servo mounts
• Four M3x12mm screws
  
• Four M3 nylon nuts

The parts needed for step 6

On each end of the servo, screw on a servo mount block using two of the M3x12mm screws and M3 nuts at either end. There is a small amount of play in the servo mounts, so make sure you tighten the servo mounts so that they are parallel to each other.

Servo mounts fixed to servo

Fit the servo with the mounts into the left side chassis plate on the same side as the long 30mm standoffs. If the servo mounts do not quite fit into the slots, loosen off the screws a bit and wiggle them into place. Remember to tighten again once you've done this.

Servo and mounts in position on the left chassis plate.

Next, wind the servo cable anti-clockwise around the 30mm standoff and thread it through the large hole.

Servo cable threaded through the large chassis hole

Place the third chassis mount at the bottom of the left chassis plate with the short side facing the servo.

Final servo mount in position

Step 7: Assembling the camera mount

For this step you will need:

• Raspberry Pi Camera
• Raspberry Pi Camera with either a Pi Zero Camera cable or a Pi 3 Camera cable depending on which Pi you are using.
• One 3mm perspex camera mount plate
• Two M2x8mm nuts
• Four 2mm washers
• Two M2 nuts

Parts needed for step 7

On a flat surface, slide the screws into the small cut outs in the perspex camera mount. Slide on two washers onto each screw.

Two washers in place on each screw.

Slot the camera in place over the two screws using the lower two holes next to the camera lens. The camera should sit in the cut out in the perspex.

Placing the Raspberry Pi Camera

Screw the two M2 nylon nuts onto the screws and tighten gently.

Camera in place on the camera mount.

Step 8: Adding the camera and camera mount to the left chassis plate

Take the part assembled in step 7 and add it to the front of the left chassis plate with the camera lens facing away from the chassis.

Camera and mount slotted into the front of the chassis

Fold the camera cable behind the camera and thread through the thin slot behind the mount. Don't pull the camera cable too tight.

Camera cable threaded through slot

Step 9: Adding the right chassis plate

For this step you will need:

• The right hand chassis plate
• Two M3x8mm metal cheese screws
• A Phillips head screw driver

Take the right hand chassis plate and place it onto the left hand chassis plate, aligning the servo mount and camera mount holes. Again you may need to loosen the servo bolts to allow for some wiggle room. Remember to tighten them once you've got the plate in place.

Right chassis plate placed on top of the servo mounts, camera mounts and 30mm standoffs

Using the two M3x8mm screws, screw them into the two M3x30mm standoffs.

Screwing on the right chassis plate

Step 10: Adding the lower chassis plate

For this step you'll need:

• The 3mm perspex lower chassis plate
• The 5mm perspex spacer
• One M3x25mm screw
• One M3 nylon nut

Parts needed for step 10

Through the centre hole in the lower chassis thread the screw and then thread the washer over the top.

Thread the long screw and washer through the centre hole

Slot the left and right chassis plates onto the lower chassis plate slots, ensuring the M3x25mm screw is pushed through the servo mount hole in the middle of the three holes. Make sure when slotting the three plates together you apply an even pressure across the lower plate to make sure it doesn't snap.

Slot the left and right chassis plates into the lower chassis plate

Using the gap between the side plates and the large holes in the side of the chassis plates add the M3 nut to the screw in the middle of the chassis. This is a little fiddly, but you can use tweesers to help you if needed.

Screw the nut onto the long screw between the chassis plates

Screw the nut down onto the servo mount below.

Step 11: Fitting the rear chassis plate

For this step you will need:

• The semi-circular 3mm perspex rear chassis plate
• One M3x25mm screw
• One M3 nylon nut

To attach the semi circular rear chassis plate, tilt the flat edge under the notches on the left and right chassis plate and carefully push it down into place using the slots as a guide. Similar to the lower plate, apply an even pressure across the rear plate when pushing it into place so that you don't cause it to snap.

Slide the rear chassis plate under the two notches on the left and right chassis

The rear plate pushed into position

Thread the M3x25mm screw from the rear chassis plate through the servo mount and screw on the nut to secure it in place.

The rear plate fixed in place with the M3x25mm screw and nut.

Step 12: Adding the on/off switch

For this step you'll just need the on/off switch with the pre-soldered battery clip.

The pre-soldered on/off switch and battery clip

Firstly unscrew and remove the two hex nuts and the metal washer without the tab. Slide the toggle switch through the smaller circular hole in the right chassis plate near the servo. Rotate it such that the toggle is facing the camera end of the chassis.

Screw the switch into the right chassis plate

There are two unconnected wires with stripped ends, one red and one black. Thread both of these wires through the same hole that the servo wire is threaded through.

Thread wires through the left hand chassis hole

Step 13: Fitting and calibrating the servo truck

Now we're ready to put the truck onto the servo at the back of our chassis. It's important at this stage to make sure that the truck is placed in the middle of the servo's range. We can't guarantee that each servo is left in the middle after it's been made so we have to do a little calibration routine.

We're going to go through what the right alignment looks like, and we'll show what a wrong alignment looks like and how to correct it.

For a well aligned truck

Gently push the servo horn on the truck onto the servo in the chassis. Make sure to apply even pressure across the truck when doing this to avoid snapping things. Make sure it's not on too hard, but just enough to engage the teeth on the servo.

Don't screw the truck into place just yet as we may need to take the truck on and off to alter it's position after we've tested its range.

Gently push the truck onto the servo head

Slowly and gently rotate the truck servo until you reach the maximum range of the servo in one direction.

Fully rotate the servo and truck in a clockwise direction

Make a note of where the maximum is either visually, with a pen or (like we did) with a small piece of electrical tape.

Move the truck and servo, again gently, to the opposite extreme of its movement and mark this in a similar way.

Servo and truck rotated to furthest anti-clockwise direction

Servo marked with extremes of rotation.

You can see our servo is close to the middle of it's range. Each tooth movement represents about 18 degrees of rotation, so if we move our truck one tooth to the left or right, it would probably be further away from central than it is now.

What to do if your truck is out of alignment

Following the instructions above, move the truck as far as it will rotate in one direction and mark it's position.

Fully rotate the servo and truck in the clockwise direction

Then rotate it gently to the maximum in the opposite direction and mark it's location.

Fully rotate the servo and truck in the anti-clockwise direction

Now rotate the truck to approximately halfway between those two markers.

Rotate the truck and servo to halfway between the two markers

Now remove the truck and replace it in a central position behind the robot without rotating the servo.

Remove the truck and replace it back on the chassis in a central position

Repeat the process above for a "well aligned truck" to double check your position is good.

Step 14: Add the front wheel.

For this step you will need:

• One foam front wheel
• One M4x45mm screw
• One M4 metal nut
• One flat head screw driver
• One 7mm open spanner

Parts needed for step 14

Align the hole in the wheel and the two holes at the front of the left and right chassis plates and slide the cheese screw through the holes. This will form our axle.

Screw on the nut using the 7mm spanner on the nut and the flat head screwdriver on the screw head. Don't screw too tightly as you might bend the perspex and even snap it.

Thread the nut through the chassis and wheel, and tighten

Step 15: Guiding the wires

Before we install the Raspberry Pi, we need to guide all of our cables into the right place. The four cables attached to the motors on the truck need to be grouped into pairs. Using the pair of rubber bands, group each motors wires into pairs and tie together (one red and one black from each motor).

Group each pair of motor wires together

Thread these two pairs of motor wires through the large hole where the servo and switch wires are already threaded.

Thread both pairs through the right hand chassis hole

Next the wires need to be guided into the correct location to make it easy to connect the wires to the motor controller. The three wire servo cable and the pairs of motor wires need to point towards the front wheel. The power cables from the battery connector and switch need to point backwards towards the truck.

Guide all wires forward except the battery cables

Step 16: Mounting the Raspberry Pi

Using four of the M2.5x6mm nylon standoffs, screw the Raspberry Pi onto the left chassis plate. The GPIO pins on the Raspberry Pi need to be closest to the lower plate ie. the Pi is upside down.

Raspberry Pi 3B+ mounted on the chassis.

Raspberry Pi Zero W mounted on the chassis with connected camera cable.

If you're using a Raspberry Pi Zero, now is a good time to connect the camera cable to the camera slot as it will become obscured by the motor controller in the next step.

Step 17: Wiring up and mounting the motor controller

Wiring up and mounting on the Raspberry Pi 3

You should have two paired motor cables sticking out towards the front of the robot. Take the pair of wires which are connected to the left hand motor as you look at the back of the robot. Unbundle these two cables and connect the red wire to the M1+ terminal and the black wire to the M1- terminal on the motor controller. Tighten the terminal screws using a flat bladed screw driver until the wire is held tightly.

Connect up the left hand motor to the M1 terminal

Similarly for the other motor, take the red and black wires which are connected to the right hand motor and remove the rubber band. These two wires will be connected to the M2 terminal on the motor controller. Take the red wire and connect it to the M2+ terminal and take the black wire and connect it to the M2- terminal. Tighten the terminal screws using a flat bladed screw driver until the wire is held tightly.

Connect up the right hand motor to the M2 terminal

Now push the controller onto the GPIO pins threading the wires around the Raspberry Pi's USB port. Using two M2.5x6mm screws, screw the board into the two standoffs on the Raspberry Pi.

Push the controller onto the Raspberry Pi header

Wiring up and mounting on the Raspberry Pi Zero

Firstly, mount the motor controller over the top of your Raspberry Pi Zero and use four of the M2.5x6mm screws to secure it into place.

Mount the motor controller onto the Raspberry Pi

You should have two paired motor cables sticking out towards the front of the robot. Take the pair of wires which are connected to the left hand motor as you look at the back of the robot. Unbundle these two cables and connect the red wire to the M1+ terminal and the black wire to the M1- terminal on the motor controller. Tighten the terminal screws using a flat bladed screw driver until the wire is held tightly.

Connect the left hand motor to the M1 terminal

Similarly for the other motor, take the red and black wires which are connected to the right hand motor and remove the rubber band. These two wires will be connected to the M2 terminal on the motor controller. Take the red wire and connect it to the M2+ terminal and take the black wire and connect it to the M2- terminal. Tighten the terminal screws using a flat bladed screw driver until the wire is held tightly.

Connect the right hand motor to the M2 terminal

Connecting the servo and power on all Pi types

Once the motors have been connected using either the Pi 3 or Pi Zero step above, we can now connect the servo cable. The servo pins are labelled "S", "+" and "-" and they are located near the motor terminals. The yellow wire needs to be connected to "S" and the brown wire needs to be connected to the "-".

Connect servo cable to "S, +, -" servo pins

Next connect the remaining red power cable to the V+ terminal on the motor controller and the remaining black cable to the GND terminal.

Connect the battery power cables to the V+ and GND terminals

If you're using a Raspberry Pi 3, connect up your camera cable now.

The standard camera cable sticks out a little, however with a replacement 20cm cable this can be run along the back of the Raspberry Pi and looped back over the top to give better ethernet port access, but this is optional.

If using a Pi 3B+, connect your camera cable now

Step 18: Adding batteries

Place 8xAAA batteries (not included in the kit) into the plastic battery holder.

Put your batteries in the holder

Slide the battery pack between the left and the right chassis plates so it rests on the lower chassis plate. Ensure that it hasn't got caught on any of the standoff screws or nuts on the inside.

Slide the batteries between the two chassis plates

Step 19: Mounting the top chassis plate

Take eight of the M3x30mm standoffs and screw pairs of them together to make four 60mm standoffs.

Join two 30mm standoffs to make a 60mm standoff

Push the threaded end of the 60mm standoffs into the four available holes on the lower chassis plate. Screw them in place using the four M3 nylon nuts on the underside of the lower chassis plate.

Screw the standoffs onto the lower chassis plate in the four holes

The top chassis plate has two sets of cut outs for access to the Raspberry Pi ports on the side. The Raspberry Pi 3B+ cut outs are two slots for the power and HDMI and a hole for the jack. Make sure the panel is the right way up for your Pi and slide it into position under the switch.

Move the chassis plate into position

Take some time to collect the wires together so they fit neatly into the cut out above the top of the truck so the top will fit on neatly. Push the top chassis plate onto the guide slots.

Push the chassis playe onto the four guide slots

The top chassis plate in position.

Using four M3x8mm cheese screws, attach the plate to the 60mm standoffs.

Screw the top on using the screws

Once you've screwed in the top plate, that's it! You now have a RockyBorg which is ready to ROCK!