Friday, February 18, 2022

Project Development

  1. Our team Chemical Device

Cooking a soft-boiled egg takes care. Too long and it's overcooked. It's too short and rough.

Perfect timing and cooling are required for the perfect soft-boiled egg.

We devised a method to make the perfect soft-boiled egg every time.

This is done by draining the boiling water from the egg after it has cooked.

When the temperature sensor detects a change, it sends a signal to the Arduino board to start the 7min delay. This allows the hot water to be drained completely after 7 minutes. In our final design, we used the Arduino Uno Board's button to start the 7 minute delay instead of a temperature sensor. This was to simplify our chemical device.


  1. Team Planning, allocation, and execution

In my team, we consist of

Chief Executive Officer: Bjorn

Chief Strategy Officer:  Vernon

Chief Operating Officer: Nigel

Chief Financial Officer: Roy

Here is our finalized BOM:

Here is our initial Gantt chart:

In the end, we did not follow the plan due to sudden changes such as the omicron variant. Hence we had to change our schedule:



  1. Design and Build Process


Arduino Programming (Done by Nigel)

https://cp5070-2021-2b02-group3-nigel.blogspot.com/2022/02/project-development.html

We wanted to the stepper motor to be able to have a 7 mins delay before turning 90 degrees for 1 min and then turning back to a close position. This will be run when the button on the board is pressed. In order to start, I had to copy and paste the code from the seller's website as it contains the code which allows the motor to move. Then in the void loop, I start off with the Toggle Button code in my Arduino Practical blog (DC Motor part) since I will be using it to run the code. Then I added a delay for 7mins (420000ms). The stepper motor has 2048 steps per revolution so, in order for it to turn around 90 degrees, I added the for a loop. Initial a (number of steps) = 0, a will keep on adding until it reaches 500 steps (90 degrees). Now I have to add the delay for every step and the direction. The minimum delay I found on the website is 2ms per step so I add a delay of 2ms in the for a loop. OneStep(false) is the direction of the step which is defined by the initial code. Currently, it is turning in a clockwise direction. For that, we wanted it to stay at this position for 1 min in order for all the hot water to drain out, and hence we added another delay for 1 min (60000ms). Lastly, we wanted the motor to turn back to its original position, so I copy the first for loop and paste it at the bottom, and changed the direction to anti-clockwise, OneStep(true) to OneStep(false). 

Here is what the code look like:




File for the code: https://drive.google.com/file/d/15UW6aG8j52MsCDbGREOLuV5RaiDPSKtf/view?usp=sharing


Design of CAD and Valve Mechanism Schematic (Done by Bjorn)


Link to his blog:

Design of CAD for 3D printed parts
CAD of Valve Disk
CAD of Valve connection


For the designing and printing of parts, we had to design and print 2 parts for our prototype, valve connection, and disk, 2 of each.

For the valve disk, I created a circle of diameter 50mm, drew 2 smaller circles of diameter 7.6mm and a small rectangle in the middle of dimensions 3.6mm x 5.2mm. Lastly, I extruded the sketch by 5mm.

For the valve connects I drew a larger circle with a diameter of 25.4mm, a middle circle of 12.7mm, and a small circle of 7.6mm. I extruded the outer circle by 5mm, the middle circle by 21.55mm, and left the small circle not extruded.

I designed the middle hole of the valve disk to be the same as the stem of the stepper motor so it fits snugly onto the stepper motor. Since the tube we purchased had an internal diameter of 12.7mm we also designed the outer diameter of the valve connections to be 12.7mm to fit the tube. The holes of the disk were designed to have a sufficient flow rate when water is being drained. The thickness and height of the disk and valve connection were chosen to have a smaller form factor for our valve mechanism.
Hero Shot of CAD

Valve Mechanism Schematic


Since we will need to drain water out from the container, we need to design a mechanism to act as a valve. Thus I created a schematic so we can base our valve mechanism design out of. We used the parts we created and purchased to make this valve mechanism. When the holes are aligned, water is able to flow through. When the disk rotates by 90 degrees the straw will get pinched thus stopping the flow of water.



Brainstorming of the Prototype (Done by Roy)


Link to his blog:


For the assembly process, from what Bjorn designed and Nigel coded, my main task that I spent the most time on was to get the prototype working as well as come out with new ideas when the old failed.

Initially, we were following a different design:


However, due to issues we faced, we had to drop this idea completely. So the team and I started brainstorming. I came out with the idea to try to implement a vacuum and to perhaps use a tap as a start-stop valve.


But the final idea that we implemented was thought of by Vernon. I did a sketch after the idea has been selected and tried to visualize the design:


We spent the next day in school to try to implement the design, such as fabricating the initial tube, mounting of motor, and testing the mechanism:



However, the tube we fabricated was proven to not be durable enough, hence in the end we used a straw instead, which meant that we had to rebuild the entire prototype by dismantling it.

Problems and Solutions

 1. Motor broke due to rusting

When we first constructed the prototype, it was working fine however we proceeded to leave it overnight. But when we opened up the prototype the next day, the stepper motor corroded badly due to water leakage, and our tube broke. We had another stepper motor that we had to switch to in fear of safety. Thus we needed to recreate our prototype.
Our final prototype failed due to the straw. As the straw was too rigid, after excessive use, it couldn't straighten back to allow for the water to pass through, which prevented the draining of the water.

 2. Problems with our Initial design





Our initial idea was for the disk to block the flow of water when the holes are not aligned but when the disk turn 90 degrees, the holes will be aligned causing a flow.

We tried adding a sealant between the gaps to prevent water leakage but the friction between the sealant and the disk is too strong for the dick to rotate. Hence we changed our design to the final design showed above.


3D printing of Parts (Done by Me)


To use the 3D printer in the workshop we had to book the printer we were going to use. Before going to workshop to use the printer, Bjorn had sent me the file of the CAD parts he designed. My job was to goto W3 to print and troubleshoot if problems were to arise.

Here is the Cura setting I used for the printer which was the Creality ender-3. I used the same settings for both parts we printed.






A small issue that arose was the sizing of the square was a little too small which we found out after the first print. It was a easy fix as we just need to adjust the length and width of the square.

Here is the photo of the parts printed.


In total i printed 5 parts. It took slightly more than 4hours to print all 5 parts. The first part was defective as it was the wrong size.

Here is a short timelapse for the Disk.






  1. Problems and solutions

After we got our prototype to work, we left it overnight. However, the next day, the stepper motor rusted badly due to the water leakages we suffered in the days before. Luckily, we had a second stepper motor which we were able to switch to.

When faced with water leakage problems in our initial prototype, we added sealant between the potential gaps, however, the added resistance proved too hard for the stepper motors to turn. Hence we had to brainstorm new ideas on the spot(view above).


5. Project file Design as downloadable file

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