Dahi Maker Testing and Designing

The brief for the Dahi Maker product given to me at Vigyan Ashram :

To Create a Dahi Maker, which gives you a good quality Dahi in 3 hours. This appliance is for everyday use in the household. The product should not involve any electronics and should be easy to use and easy to assemble.

User Survey

The project started with working at what is that the customers require. For this, I designed a questionnaire on Google forms. Then it got circulated throughout different Whatsapp groups with the help of my dad. The outcome of the survey was then studied, and the parameters of the product were finalized.

The question asked in the survey were:

How often do you consume Dahi?
How much Dahi do you prepare at a time?
How much time does it take to prepare Dahi?
What time of the day do you prepare Dahi?
What kind of utensil do you use to prepare Dahi?
What do you prefer homemade Dahi or packed Dahi?
What are the reasons for not making homemade Dahi?

The survey results are shown in the graphs below:

https://docs.google.com/forms/d/12o9HPDqcpmiHpECHD17_zmMxGCoG4SKroAEDS0o5X58/edit

(We got a good response from 110 people)

Redefine the Brief

To create an appliance with a capacity of 750ml(max.), which gives you good quality Dahi every day at any temperature. This appliance should be easy to use and should use the least amount of electronics.

Solution and Experimenting

The two most important parts of the problem is how to control and minimize the heat loss and how to efficiently transfer heat to the dahi vessel. With this we also had to take care of the amount of insulation required to reduce the heat loss.

The Idea for this product was that we will use an insulated bag and with that we will take three stainless steel containers that can sit on top of each other. The bottom and top containers will have boiling water and the middle container will have warm milk with starter culture of Dahi. This setup would be kept closed and undisturbed for 4 hours to get the desired outcome.

The experiment started with using a Tupperware bag which has a lining of form insulation and three stainless steel tiffin containers.

Before starting the experimenting, we had to have a device to record the temperature data at every interval of time. For this we made a data logger for temperature.

Data Logger for Temperature

The data logger has three components:

Arduino Uno
Temperature Sensor
SD card module

Using different websites to research and figuring out different connections to get getting the optimal output I build the data logger for temperature.

http://www.manelsoft.com/projects/arduino_microsd_data_logging.aspx