Putting It All Together

Now that we have all the parts built, it is time to put it all together. Lets start with the front and back chassis pieces:

Before we connect these two together, we are going to need to do a little drilling. The extrusion type of 3D printer we used cannot generally produce precise hole diameters. Therefore, we purposely designed the parts with holes that are slightly smaller than needed and need to drill them the the correct sizes. Use a 3/32 in. bit to drill out the following holes:

Then use a 3/16 in. bit to drill out the following holes:

Finally, use a 1/8 in. bit to drill out the following holes on both sides of the front chassis piece:

Now using the 1/4 in. 8-32 machine screws attach the front chassis piece to the rear as follows:

Note that you don’t need to put screws in every hole, the seven screws shown should hold it together just fine.

Next, install the encoders using two 1/2 in. 4-40 machine screws. Pay particular attention to the position of the two spacers:

When both are installed, it should look something like:

Now press fit the encoder coupler on to one of the motors as shown below. Make sure you attach it to the side that does not have the nub sticking out.

We will now attach the motor, but before we do that, you need to ensure that the flat portion of the two potentiometers line up, as shown below:

Now mount the motor by aligning the flat portion of the encoder coupler with the flat edges of the potentiometers. Attach the motor to the chassis using two 1-1/4 in. 4-40 machine screws as shown below:

Then, in the same manner, mount the second motor on the other side:

Now attach the swivel wheel to the wheel mount using two 1/2 in. 8-32 machine screws:

Then attach the wheel mount to the robot using three 1/2 in. 8-32 machine screws:

Now mount the Raspberry Pi onto the top of the chassis using four 3/8 in. 4-32 sheet metal screws:

Then attach the Arduino clamp using one 3/8 in. 4-32 sheet metal screw:

Then plug the Arduino board socket onto the Raspberry Pi and attach it to the clamp with two 3/8 in. 4-32 sheet metal screws. Be sure to use the two spacers. Note that you will need to remove the Arduino Nano from the board in order to access one of the screw holes:

Now mount the motor controller using two 3/8 in. 4-32 sheet metal screws:

Finally, mount the two IR sensors on the bottom of the chassis using two 3/8 in. 4-32 sheet metal screws:

Finally, attach the wheels by press fitting them onto the motor shafts. Your robot should now look like:

Next: Wiring The Robot