PROJECT Development
Hellooo! Welcome back to my blog! Unfortunately, this will be my last blog. I will be blogging on how my teammates and I manage to successfully make a Carbon Monoxide(CO) Detector and Ventilation System, with all the knowledge that we had gained in this semester. 🤞
Briefly describe your Chemical Device
What is a CO system?
Our chemical device is a Carbon Monoxide (CO) detection System that is use to detect CO in the atmosphere, and is able to alert people in the room, and help to ventilate the CO out of the room. The CO system is best placed near a window, so that the fan can be effectively use to ventilate the room with CO. The CO system consists of an Arduino Board, Breadboard, male-to-male and female-to-male Dupont Wires, LEDs, CO sensor, DC motor and a fan. The CO system is able to potentially safe one's life by detecting the poisonous, colorless, odorless and tasteless CO in the atmosphere which humans cannot detect by our 5 senses.
What is the objective?
CO can be produced easily, even
at homes. Some common sources which produce CO are motor vehicles, water
heaters, boiler, gas stoves and cigarettes. Furthermore, since CO has no odor,
color or taste it cannot be detected by our naked eye or by our senses. This
means that dangerous concentrations of the gas can build up indoors and humans
have no way to detect the problem until they become ill. When people become
sick, the symptoms are similar to flu, which can cause victims to ignore the
early signs of CO poisoning.
CO will bind to haemoglobin found
in red blood cell. This decreases the amount of oxygen which haemoglobin can be
binded to, thus humans will face difficulty breathing when breathed in too much
CO. When CO is bind with haemoglobin, this reaction is non-reversible. Therefore,
when breathe in too much CO, one may lose consciousness and die due to lack of
oxygen.
Therefore, to prevent humans from being poison by CO which is fatal, our CO device can be used.
How does it work?
Our CO system is able to work in two ways. Firstly, when there is low concentration of CO in the air, and secondly, when there is high concentration of CO in the air.
When CO concentration in the air is below the dangerous threshold value of 175ppm, the LED on our CO system will be green.
When CO concentration in the air is above the threshold value of 175ppm, the LED will change to red, built in buzzer on the Arduino will be sound, and the DC motor which spins the fan will start spinning to ventilate CO out of the room.
To summarized, it works like this:
Team Planning, Task Allocation and Execution of Project
Members | Allocated Roles |
Lau Jun Foong Wayne | CEO, in charge for the Design and CAD of the Chemical Device. |
Rong Yiren | COO, in charge of Arduino UNO and Coding of the Chemical Device. |
Wong Kea Tzer | CFO, in charge for 3D Printing and the Construction of the Chemical Device. |
Finalised Bill of Materials (CO System):
Finalised Gantt Chart:
link for Gantt Cart:
Design and Build Process:
Part 1. Computer Aided Design (CAD) of the CO sensor Box done by Wayne
Part 2. Programming of CO System done by Yiren
Link to Yiren's Blog: https://cp5070-2021-2b01-group4-yiren.blogspot.com/2022/02/project-development.html
Part 3. 3D Printer Settings done by Tzer
Link to Tzer's Blog: https://cp5070-2021-2b01-group4-tzer.blogspot.com/p/project-development.html
Documentation of CAD CO System Sliding Lid Box.
Step 1: Setting up the Parametric dimensions of our Box
This are our dimensions use for our sliding box. Feel free to change your dimension values to your need!
Step 2: Creating of the Box
Under the "Solid" tab, click on "Create and choose the box option.
We had selected the X-Y origin plane to sketch our box on, and then started our sketch on the origin point.
We will be using our parametric dimensions for the box. Simply type in “length” and “width” for the dimensions. For the height of the box, similarly, type in “height”. Once done, click on the “Ok” button.
Step 3: Making the Box Hollow
To make the box hollow, we shall use the "Shell" command, also located under the "Solid" tab.
Click on the top of the box, and specify the thickness of the box as "Thickness". Once done, click "ok".
Step 4: Create a lid which can slide back and forth
Right click on the front phase, and select "Create Sketch".
As we want our model to be dynamic, we will be projecting the outer edges. This will make it easier for us to fully constrain our sketches, ensuring that our model is truly adaptable. To activate the Project command, simply click on “P” on our keyboard.
We can click on the middle of the rectangle which will project all 4 edge lines of our current sketch. Once done, click “Ok”.
We can see that the projected geometry is defined with the colour purple.
Now, we will also want to project the insides edge lines. Right click anywhere and click on “Repeat Project” and choose these points. Once done, click on “Ok”.
This will help us identity the dovetail angles, so that they adapt base on the thickness of our shell command.
Under the Sketch tab, click on line and create a line at a 55° angle at our previously projected point. For the length, we will be using our thickness dimension. Having our angle at 55° means that we do not need to use any support materials.
To make things easier, we are going to make half of the dovetail shape, and then mirror it over to the left. However, before we are to mirror it, we have to make sure that it has been fully constrained. Looking at our sketch in the browser, we do not have the fully constrained lock icon.
We will notice that we have a point on the upper right, which is not constrained which was cause by our angle dimension.
We can drag out the point, then select the point and the corner point and add a coincident constraint. The lock icon should appear.
Let us now create a line and run it down the middle. Make sure to start the line where it snaps at the midpoint constraint.
We will always want to make sure that the length matches the length of our angle line so we will utilize constraints.
Shift click the end points of each line, and select the horizontal constraint on the toolbar, which will force them to stay in the same height.
Since our line is only used for the mirror command, we will select it and change it to a construction line.
Lastly, we will use the line command to connect the two end points, which finishes off half of our dovetail lid.
Using the sketch mirror command from the toolbar, we can select the two lines for the objects, and the construction line as the mirror line. Once done, click on “Ok”.
To cut away this slide, we will use the extrude command under the solid tab. Select the trapezoid as the profile and set the extent type to “to object”. This will allow us to select the back inside face of the box, ensuring that our cutout always runs the length of the box. Once done, click on “Ok”.
Once we click “Ok”, we can see that we have a nice ledge for the lid to slide through.
Step 5: Creating the Lid
Click on “New Component” and name it “Lid”.
To keep this model dynamic, we want to project our current cutout shape to a sketch on the front plane. We will then offset that projection to factor in our clearance, so that the lid is able to slide through in the actual 3D-Print.
Lets create a new sketch at the front plane of the box.
Again, activate the project command by typing “P” onto our keyboard. We will select all 4 lines which make up our trapezoid.
We will not use the offset command under “Sketch” This offset will serve as the clearance between the box and the lid. Ensure that the “Chain Selection” button is clicked so that we can click the bottom of the trapezoid as a whole. The offset position shall be the dimension we had specified in the parameter. Make sure that the offset (red line) is in the inside of the box, if not, we shall use the “Flip” option.
When we zoom in, we can see that our offset angle lines (red line) do not touch the top.
To get around this, we shall include the top 2 edges of the model to our offset geometry. Unclick on “Chain Selection” and select the top 2 edges. The diagonal lines now extend pass the top of the box. Once done, click “Ok”.
With the line tool, we can connect the 2 angle lines by running it through straight across. We will just want to make sure that they snap into place where the projected lines and offset lines intersect.
Once the line is complete, we should have a fully constrained sketch.
With the solid extrude command, we can run this profile to the back inside wall of the box, just as we did with the cutout. Remember to set the “extent type” to “To object” and select the back wall. We can include our clearance length under the offset. Once done, click “Ok.”
Step 6: Create the Thumb Hole on the lid
Activate the Lid component, and then we will create a new sketch at the front of the lid.
Under the sketch tab, click on “Ellipse”. Again, from the midpoint (make sure to see the midpoint constraint triangle symbol), create an ellipse and set the diameter to thumb_hole_diameter, and the height to thumb_hole_height.
We will then use the extrude command to cut this away. In the extrude dialog, we have to change the start option to “Offset Plane”. This will allow this extrude cut to start at a specified offset distance away from our sketch. We will set the offset distance to -10mm. Make sure the operation is set to cut, and also define the distance to 5mm.
Once all this are done, we are done with our box!
It should look like this:
We will now be creating holes for our box. These holes are for our DC motor wires, USB wires, LEDs and our CO sensor.
Step 7: Creating the holes
Before we get started, these are the dimensions for our front face boxe. We have followed each dimensions specifically.
To create our holes, go to the "Create" tab and choose ellipse.
Specify our dimensions needed for our first hole, which is for the LEDs. We have specified a height of 5mm, at a 0 degree angle. When done, click enter.
For the length of the ellipse, we have specified it to be 18mm so that it can fit both the green and red LEDs.
To create the second hole for the CO sensor, we have decided to use a circle. We can locate the circle tool under the "Sketch" tab. As the diameter of our CO sensor is 15mm, this shall be the diameter of our circle.
Now, to position our holes to where we want it to be, we have used the tool "Sketch Dimension". Simply click on two points and specify the distance in between them.
To extrude the holes which we have made, simply extrude the holes, and ensure that the operation is set to "Cut".
Now, we will create the holes at the side.
After everything has been done, this is how our box should look like:
Here are some hero shots of our successful 3D-Printed Model using our CAD!
Embed File for Downloading:
Plain Box with lid:
Lid:
Box with holes:
Hero Shots!
Problems and Solutions
Problem #1: Motor cannot be controlled
Solution: We consulted with Mr Mark who is very experienced with working with Arduino systems and he suggested that we use a motor controller as he had a spare one in the Makers Space. He was extremely helpful as he not only explained what was wrong, which was that the DC motor cannot be controlled using only the parts provided in the maker UNO kit as it would not allow for the DC motor to be turned off when the system is powered, but he also told us the necessary information on the new part that he gave to us which made implementing this new part into our system easier.
Problem #2: 3D-Printing takes too long
Solution: With the default settings in place, the printing time for the whole box was estimated to be around 12 hours. To solve this problem, we had tuned the settings for the print speed. For an Ender Creality 3D printer machine, the default speed was 50mm/s. The max speed is 200mm/s. Thus, we had increased the printer speed to three times the default value, 150mm/s. This reduces the time needed to print the whole box to around 8 hours.
Problem #3: 3D printed Lid is unable to be slotted inside the hole of the 3D printed Box.
Solution: Using a file to gently file down the side of the lid and the clearance to make the gap larger, the lid can now be slotted into the hole of the 3D printed box.
Reflection:
In the beginning, we thought that this project would be very time consuming, and extremely tedious as it was our first time starting and doing on an actual project. The project given to us was to programme and develop a CO system which sounded very daunting initially. However, after weeks of tutorial lessons, we had gained more knowledge such as programming and 3D printing which gave us the skills and knowledge necessary to be competent for this project. Now, after successfully completing the project, we can say that it was not as difficult as we had initially thought. Instead, it has helped us to gain new skills, such as finding resources to help us with our project, and even problem-solving skills as unexpected problems may arise at different stages of the project.
Since we were assigned the project at the beginning of this module and every tutorial builds us up on the skills and concepts required to get us closer to completing the project. We tackled this project on a week-by-week basis where we would try and apply whatever we had learned from the tutorial that week into our project. This approach allowed us to keep everything on track and to not let the workload spiral out of control. Not only did this approach help us out with time management, but it also helped ensure that the work we produce is of the highest quality as we do it every week and are not rushing through it last minute.
We have learned a lot of things in this module and the biggest takeaway made from this journey is to always check that we have accounted for all the components in the design. With all this experience that we have gained, we now feel much more confident and competent going into our capstone project.
Other Downloadables:
1) CAD files are embedded above.
2) Code for Arduino Programming:
3) .STL files for 3D printing
THANK YOU FOR READING
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