Assignments

• Propose a final project that integrates the range of units covered and answering:
  • What will it do?
  • Who has done what beforehand?
  • What will you design?
  • What materials and components will be used?
  • Where will they come from ? and for the electronic parts
  • How much will they cost ? and for the electronic parts
  • What parts and systems will be made ?
  • What questions need to be answered ?
  • How will i be Evaluated ?

Subject¶

As Described on my Final project page, I want to make a monitored worms composter.

First sketch¶

GENERAL DESIGN	OPERATION

Aims of the project¶

I started thinking about this project 2 years ago, but have not had the opportunity to spend time and energy on it. I want to seize the opportunity of the Fabacademy to progress in the realization of a first version of the worm composter.

I separated the objectives into 2 categories those I set for my Fabacademy final project and those in the long and mid-term objectives.

Objectives for my Fabacademy final project¶

• Demonstrate my Fabacademy learning outcomes
• Get a working prototype allowing:
  • to facilitate use by alerts (to ensure the right conditions in the composting process)
  • to monitor data (temperature and humidity) during composting
• Find an attractive design
• Develop documentation to allow appropriation and upgrades by other users

Long and mid-term objectives¶

• Participate in a community of users sharing:
  • advices
  • worms to set up worm composter
  • composter outputs (worm juice and compost)
  • data
  • digital fabrication files
• Improve the product by users feedback
• Monitor data during composting and correlate it with the user observation

State of art¶

DIY solutions¶

There are many DIY solutions of different shapes and using different materials. I did not find a DIY project using digital fabrication.

Here are some DIY examples:

	Polystyrene tank	Plastic tray	Wood tray
Pictures
Link	Nature obsession	Nature obsession	Saint-Brieuc agglomération
Strengths	Good thermal insulation Lowcost	Easy to build and maintain Light in weight	Porous material for a good ventilation Good thermal insulation
Weaknesses	Esthetic Durability	Bad thermal insulation Holds water	Rapid deterioration heavy Dries faster
Cost	$	$$	$$$

Commercial solutions¶

Commercial solutions exist at prices ranging from 65€ to 230€.

	Lombric&Co	Can-o-worms	Wood tray
Pictures
Link	Les gallinules	Store	Vers la terre
Strengths	Esthetic Multifunctional	Good documentation	Wheels Ventilation
Weaknesses	On going development	Bad thermal insulation	Bad thermal insulation
Cost	?	$$$$	$$$$

Functional prototype description¶

Starting a worm composter is not easy when you do not know. This requires being vigilant with inputs, especially at startup. If it is badly managed, nuisances can appear (odors, midges …). Worm composter is also vulnerable to environmental pressures, especially to temperature and humidity. To facilitate the composting process it’s necessary to provide optimum conditions.

Worm composting requirements¶

• Temperature must not exceed 25°C nor fall below 15°C. Beyond these values ​​the worms do not work (and below 0°C they die!). The optimum temperature is between 20°C and 25°C.
• Ventilation is an important parameter, indeed, worms are living beings and need oxygen
• Light is not required because worms live in the darkness
• Worms flee noise and vibrations
• Humidity: the environment must be wet, but not too much
• The ratio of carbon to nitrogen must be balanced

What will you Design¶

I plan to Design Everything from the Composter itself to the Electronics (inspired from the projects available i the course)

What will it do¶

Of course, it should allow worms to produce compost. To help the process monitoring, we wish to measure & give feedback on : - Temperature - Humidity - Moisture level

What Material will it Use¶

I will use Plywood for the Composter itself, but I will need some other part to get the “worm Juice” from the composter to a Tank or any liquid container.

• One 250x122mm panel of 10mm plywood should be enought (40€ at our local reseller).
• Electronics will be DIY based on ATmel micro-controlers, ATTiny or ATMega: estimated cost between 10 and 20€
• Temperature & Humidity Sensors could be DHT22 (around 10€ on Digkey)
• DIY Conductivity sensor, say 1€ if we just measure a resistance ?
• Moisture sensor : ?

Total (large) Estimated cost between 60€ & 80€ for everything, should be enev ledd that that.

What questions need to be answered ?¶

For Moisture sensor, I didn’t know what to use. I asked Neil & He advised to make a capacitive sensor with two electrodes for measuring the conductivity.

The way electronics will be made and organized was also a question, choosing between : - one single board for sensing & display, base one ATMEga considering the limits on ATTiny - Multiple ATTiny Boards using serial communication, considering it will be easier to produce and test along the Fab Academy, during the electronics input and output weeks.

Tank and reservoir could be Made or bought.

How will it be evaluated ?¶

• It has to show mastery of most of the skills I will learn
• The result should be integrated (electronics, wood parts, cables)
• I should be well documented and others should be able to make it