I had a rough idea and visualisation of my final project in week 1, but I only started to draw my design on 18 Apr 2019 (which is after week 13 - Applications and Implications week). It took some time for the components which I ordered online to arrive, like the dust sensor module, power switch, power jack, etc.
What will I design?
Enclosure Box (or case)
The enclosure box will provide protection against water, dust, insect, etc. I intend to use 3mm acrylic plastic as it will be rigid and strong.
To hold the internal components like LCD display module, dust sensor module, power switch, power jack and buzzer in place. This will be 3D printed. Since it is 3D printed, I try to use less material as possible in my design but ensuring it will be rigid and strong.
PCB etching, soldering
The electronics board will integrate the various components (mainly dust sensor, LCD, Buzzer) together.
My design of the enclosure box and support frame using Autodesk Fusion 360
1) I started to work on the 3D design on 18 Apr 2019 after the 'Output Device' week, referring to the datasheet for measurements as the dust sensor module has not arrived yet
2) Drawing the dust sensor module using Fusion 360
3) Downloaded a 3D model of the LCD display module with I2C interface drawn by 'valand70' from Tingiverse. This is just for reference only to draw out my enclosure box for the LCD display module
4) Drawing a mock-up model of my electronic board (2 inch x 3 inch FR1 single sided copper clad)
5) Typing in parametric values for my enclosure box (length, height, width and thickness).
6) Drawing the front of my enclosure box
7) Front of my enclosure box
8) Measurement of the actual physical buzzer after getting the component from Fab Lab
9) Drawing of buzzer
10) Measurement of the power jack and 'on/off' power switch
11) Started drawing of the base of the Support Frame. Integrating the 5.5x2.1mm power jack and power switch on the base
12) Support frame (base). Drawing of two small wire holders at the side.
11) Support frame (Vertical)
12) Enclosure Box with all the components fitted nicely inside.
3D Print the Support Frame
A1) Printed mock-up piece of the power switch and power jack to check on the dimension and strength of the support. Used infill of 5%.
A2) Mock up piece of LCD module and dust sensor. The dust sensor too tight to be slotted in, need adjustment.
A3) Actual printing. Support Frame (Vertical) - infill: 20%. Support Frame (Base) - infill: 30% for rigidness and strength.
A4) Finished Support Frame
A5) Front of finished Support Frame
Laser cut of the enclosure
B1) In Fusion 360, copy over and create new sketches for laser cutting. Make adjustment to compensate for kref, offset by 0.1mm.
B2) I picked up a piece of 3mm thick recycled acrylic sheet from the recycle bin in the fabSTUDIO to laser cut and observe whether the dimension for the openings are all correct.
B3) Laser cutting of 3mm thick recycled acrylic sheet. Setting Speed:20, Power:90%, Frequency 90%.
B4) My mock up model (for testing only)
B5) My mock up model (for testing only). Made some minor adjustment to the dimension of the openings of the dust sensor as well as the buzzer.
Photos of my completed PM2.5/PM10 Dust Sensor
The first few 3D prints failed due to curved-up of the base surface, malfunction of 3D printer, filament not flowing properly, etc. It resulted in a bit of delay.
In term of design, an after-thought arises after I printed my parts, I think I can further compact everything and reducing up to 20% or 30% space as well as material. Maybe by having the electronic board slotted in vertically instead of flat.
For laser cutting, the 3mm thick recycled acrylic sheet is easier to handle and join up together as compare to the 3mm plywood. The surface of the plywood near the joints tend to have some peeling off after you assemble and dismantle a few times.