Here's the stack top-down:
To stack up things firmly, standoffs and acrylic plates are used. I bought some nylon standoffs with screws and nuts from Amazon.com (nylon standoffs are not as strong as brass, however it is more flexible with deviations in my hand-made project):
Different component uses different sizes:
- Zumo base uses M2 screws
- Raspberry Pi, Arduberry, HATs uses M2.5 screws
- Pan/Tilt Kit uses M2 screws
- Camera board uses M2 screws
Cut acrylic plates
For acrylic plates, HDPE is the best material. It's easy to get a 1/8" HDPE board from Amazon:
Most woodmaking tools and skills can be applied to HDPE, sometimes easier than wood.
To cut HDPE sheet, a high-teeth hacksaw is good enough. Cutting through wholes from a HDPE board is a little tricky. I bought a wire saw from Amazon to do this work:
To cut a shape in the middle of the board, first drill 1/8 wholes at each corner of the shape, and then put the wire saw blade (a wire) through the whole, install on the frame. Now you can cut in the direction you want.
The last thing is sanding papers (I use 60 for fixing the edge and 150 for finalizing). Sometimes a sharp knife works better than sanding papers.
The picture of a customized HDPE plate with standoffs:
And assembled pictures:
Stack Servo HAT
To stack between Arduberry and Raspberry Pi, the packaged GPIO female header is too short and can't be used. GPIO Stacking Headers should be used.
And due to the limited space, Right Angle Headers should be used to connect servo cables on the side.
It's a little tricky connecting the power. The packaged power connector is not used because I prefer using jump cables. I soldered two pins and bent them a little to save the space:
The picture with servo HAT stacked:
Raspberry Pi lays on the top. If Raspberry Pi 2 is used, a USB Wifi Adapter is needed (Raspberry Pi 3 has built-in Wifi).
Pan/Tilt Kit with Camera
Mounting the Camera on the Pan/Tilt kit is not easy. I have to build a small frame to mount the camera board and fit into the bracket of Pan/Tilt kit. I cut a small piece of HDPE to fit into the bracket, luckily, the depth of the bracket is 3/8". After I put 1/4" standoffs behind the 1/8" thick HDPE, the little frame slides into the bracket perfectly.
The flex cable shipped with camera board is too short. I ordered a 300mm one from Adafruit.
The hardware part is completed. Write a simple Node.js with johnny-five for a test drive.
The next step starts software part, stay tuned...