This page includes a wind tunnel induction where I measured the horizontal drag of different shaped objects. A plasma cutter induction describing the plasma cutter and what it does. A technical drawing and CAD model of a bracket as practise and a multimeter guide package for those who want to know how to use a multimeter.
Multimeter Guide Package
I was invited to an electronics workshop to learn about how to use different electrical equipment and how to build a circuit. For this workshop I was tasked with producing a guide on one of the electrical devices used. This was the multimeter.
Please visit this website to see the full guide for the multimeter: https://blogs.brighton.ac.uk/eelabs/multimeter/
I worked with two other people to create this webpage, they were Iain and Sam. For my contribution I created an image with the multimeter and I have labelled the essential buttons and options which you most likely need to know in order to use the device. We felt that this would be useful for anyone wanting to use a multimeter and we also felt that it could go alongside Iain’s video about the multimeter.
Multimeter essential buttons and options
My other contribution was a little tutorial on how to use the multimeter to test circuits (most specifically testing a moisture tester), I have provided the equipment that you would need as well as an explanation on what you need to do to obtain a result.
To go with the tutorial I have also provided a brief guide on how to make the moisture tester, so if you want to test that specifically you can. I have provided the equipment and components that you needs such as a soldering iron, resistors, LED, etc…
How to build and test the Moisture Tester
Wind Tunnel
I was taught how to use the wind tunnel, how to take measurements from the wind tunnel and how to use the data to tell which object are more or less aerodynamic. This wind tunnel was used to measure the horizontal drag.
The wind can go from left to right or right to left. If the wind goes from right to left then the drag forces will show a negative number. as a result the lower number out of the tests represents the highest drag force.
At the time of using the wind tunnel, the thermometer measured 21 degrees Celsius. And the barometric pressure (air pressure) was 171.0 mm of mercury.
These tests used a 3 kilo load cell, a 12V power supply and a multimeter which measured volts but was calibrated to convert to newtons. There was also an anemometer which was used to measure the wind speed m/s.
For each test results results were taken at 0 RPM to 800 RPM in increment of 200 RPM
The image above was the first shape that was measured, this shape has two flat ends and was expected to have high drag forces.
| RPM | Flow Velocity (m/s) | Drag Force (Newtons) |
| 0 | 0.0 | 0.13 |
| 200 | 3.5 | 0.06 |
| 400 | 8.8 | -0.3 |
| 600 | 14.4 | -1.08 |
| 800 | 20.1 | -2.24 |
The next shape that slightly different, with the front having a dome shape, this shape was expected to still have quite a bit of drag but not as much as the first test.
| RPM | Flow Velocity (m/s) | Drag Force (Newtons) |
| 0 | 0.0 | 0.13 |
| 200 | 3.6 | 0.07 |
| 400 | 8.8 | -0.17 |
| 600 | 14.5 | -0.76 |
| 800 | 20.1 | -1.6 |
After these shapes were measured and the next thing that was measured was the bracket without holding any shape. This was to see if this had any affect on the results of the previous tests. This was tested twice and two sets of results for repeatability were produced.
| RPM | Flow Velocity (m/s) | Drag Force (Newtons) |
| 0 | 0.0 | 0.07 |
| 200 | 3.7 | 0.04 |
| 400 | 8.8 | -0.15 |
| 600 | 14.5 | -0.60 |
| 800 | 20.3 | -1.24 |
| RPM | Flow Velocity (m/s) | Drag Force (Newtons) |
| 0 | 0.0 | 0.07 |
| 200 | 3.7 | 0.04 |
| 400 | 8.8 | -0.16 |
| 600 | 14.5 | -0.60 |
| 800 | 20.1 | -1.24 |
After testing the bracket, the load cell was tested on its own as well.
| RPM | Flow Velocity (m/s) | Drag Force (Newtons) |
| 0 | 0.0 | 0.0 |
| 200 | 3.6 | -0.01 |
| 400 | 8.8 | -0.07 |
| 600 | 14.5 | -0.22 |
| 800 | 20.2 | -0.46 |
After testing the load cell, a comparison between a steel ball and a golf ball was produced.
Here are the results from the golf ball:
| RPM | Flow Velocity (m/s) | Drag Force (Newtons) |
| 0 | 0.0 | 0.01 |
| 200 | 3.6 | -0.01 |
| 400 | 8.8 | -0.12 |
| 600 | 14.6 | -0.38 |
| 800 | 20.1 | -0.73 |
Here are the results from the steel ball:
| RPM | Flow Velocity (m/s) | Drag Force (Newtons) |
| 0 | 0.0 | 0.02 |
| 200 | 3.6 | 0.0 |
| 400 | 8.8 | -0.10 |
| 600 | 14.6 | -0.37 |
| 800 | 20.2 | -0.75 |
From the results collected I managed to calculate the Reynolds numbers and Coefficients and I was able to produce a couple graphs from this. Reynolds number was produced using the viscosity, velocity and diameter.
Image from: https://www.sciencedirect.com/topics/engineering/reynolds-number
DOWNLOAD: Wind Tunnel Results
Engineering ToolBox, (2003). Air – Dynamic and Kinematic Viscosity. Available at: https://www.engineeringtoolbox.com/air-absolute-kinematic-viscosity-d_601.html
Plasma Cutter Induction
I went to a plasma cutter induction where I was shown how to use a plasma cutter. The plasma cutter is able to cut any CAD drawing so long as the file of the drawing is exported as a DXF file. The plasma cutter runs on G-code and is a high speed precision metal cutting machine and was used to cut sheet metal during the induction.
I was also shown that in order for the machine to be used properly I needed to reference the XYZ axis’ relative to the position of the metal in the machine.
This box was produced using the plasma cutter to cut out the net shape of the box and then using a bending machine and mallet to bend the sides of the box.
Skill Learning: Technical Drawing (Hand and Solidworks)
For my skill learning I wanted to practise and better my technical drawing skills, I used to draw on a regular basis but unfortunately due to other circumstances I was drawing less and less. My aim is to improve my technical drawing skills as I believe that this is an important aspect of engineering. To better my drawing skills I decided to attempt to draw something that wasn’t too simple but at the same time something that wasn’t basic.
I ended up drawing this. This is a component which combines with another to form a bracket.
I started with drawing three views, the top, back and side. I measured the dimensions and made my drawing a 1:1 scale as the component was rather small.
This is my technical drawing of the bracket part:
This activity took me little time and I feel as though I have become quicker and more accurate with drawing. I feel I should have made the outlines of the drawings bolder to make them stand out more and I think some of the dimensions could have been better placed.
By performing this skill learning task I have revised on how to draw technically and I am starting to build my muscle memory back.
Continuing to practise drawing and better this skill will help in the future as 1. I will need a drawing skills for both engineering drawings and designing concepts, images, posters, etc… and 2. this will allow me to better my engineering drawings both hand drawn and via computer software such as Solidworks.
Valcke T. Basic Sketching Techniques for the Industrial Designer. This book was used to help me draw this engineering drawing.
Solidworks
From the hand drawn technical drawing I was able to replicate the design of the bracket component, I have added fillets to the design to make this as accurate to the original design, I had forgotten to at these to the hand drawn technical drawing. This is also a 1:1 scale.
DOWNLOAD: Bracket Component
After producing the Solidworks version I began making a Solidworks drawing of this component. I think that the drawing could have been bigger and the dimensioning could have been placed more neatly.
What I want to improve on and learn in the future
In the future I would like to have a go at making more complex codes, as well as learning a little more of electronics. And I would also like to use the manufacturing machinery more.
I believe that improving my skills in these areas would allow me to help out and cover a wider range of problems and I believe it would allow me to provide better solutions and more complete projects.