13. Applications and implications¶

Assignment¶

Propose a final project masterpiece that integrates the range of units covered, answering:

Your project should incorporate 2D and 3D design,

additive and subtractive fabrication processes,
electronics design and production,
microcontroller interfacing and programming,
system integration and packaging

What will it do?¶

Pump water to feed plants
Stop pumping when the water tank is empty
Start pumping when the water tank is filled

Who’s done what beforehand?¶

Most of the hydroponics designs that I have seen on the Internet are based on a plastic tank, or PVC pipes assembly.

This website shows the diversity of existing DIY hydroponics systems.

My favourite design is the #10, with plastic bottles. But the structure is not rigid and it has to be wall-mount. I want to design something easier to move from a place to another.

What will you design?¶

3D print model for the planters. I will design it in Openscad so it dimensions can be adapted easily
PCB for pump control and water sensor connection
Drawing for cutting the bottle that contains the electronics
Drawing of a board to screw the electronics in place
Drawing for cutting the bottles caps

What materials and components will be used?¶

A wood pallet
2 empty plastic bottles (1.5l)
A water pump
An AC-DC converter (220v → 5v)
A microcontroller board
A low-voltage interface for the water level sensor
A high-voltage interface to control the pump
3D printing filament for the planters (I will try PLA and PET-G)
Flexible PVC tubing
Plastic connectors that fits in the PVC tubing
Insulated wires for the water level sensor
A lot of electric connectors
Hydroponic media (clay balls or coconut fiber)

Where will come from?¶

These materials are re-used, I found it in trashes :

A wood pallet
2 empty plastic bottles (1.5l)
A water pump, from a defect Senseo coffee machine
An AC-DC converter (220v → 5v), from an old cellphone charger
PTFE insulated wire

These materials are from the lab stock :

⅛” ID - ¼” OD flexible PVC tubing
6mm ID - 8mm OD flexible PVC tubing
3D printing filament (PLA/PET-G)
Electronic components
Electrical connectors and jumper wires

I only bought the clay balls from a local store named Brico.

How much will they cost?¶

Clay balls can be found in any gardening store for less than 8€.

All the other parts were already in the lab, so I got it for free. Anyway, I listed the components in this table :

About the 3D printing filaments, I will try these :

Prusa grey PLA
Prusa orange PET-G
RS PRO translucent green PET-G
Unic-3D clear PET-G

What parts and systems will be made?¶

Two bottle caps
Planters
Two PCBs for the electronics
Two wood panels, to hold the bottles
A water level sensor
Water tubing connectors
Some flexible PVC tubing with drills, for water dripping

What processes will be used?¶

The bottle caps can either be laser-cut (in the original cap) or 3D printed
The planters will be 3D printed
The electronics PCBs will be cnc-milled
The wood panels will be laser-cut or cnc-milled
The water level sensor will be made by hand, from insulated wires
The flexible PVC tubing will be drilled with a Dremel tool.

What questions need to be answered?¶

The main questions are about protecting the setup from water leakage :

Are the 3D printed planters watertight ?
Are the 3D printed tubing connectors watertight ?
How should I seal the bottle that contains the electronics ?
How can I make a power entry that is suitable for outdoor use ?

How will it be evaluated?¶

The final setup needs to fulfill this checklist :

Electrical safety
Leak-proof water circuit
Pumping stops when water level is low
Pumping starts when water level is high