Week18. Project Development

What tasks have been completed? What tasks remain?

Based on the concept of the project, I developed the following execution plan:

Step	Description	Status
1	Requirements and Planning	Completed
2	Material Procurement	Completed
3	Circuit and Mechanical Design	In Progressd
4	Software Development and Testing	In Progressd
5	Structural component production (including CNC cutting, laser cutting and 3D printing)	In Progressd
6	Hardware Assembly and Debugging	In Progressd
7	Make a video and PPT to introduce my project	In Progressd

What has worked? what hasn’t?

What has worked?

1. The appearance part

The appearance part went smoothly. After testing some cutting methods, the laser-cut shell was perfected. this is the sketch of my final project.

first I need to test the curved surface, here is the one the 0.1mm gap is broken，

0.2mm gap seems work

test chimeric structure it seems work

then I use Adobe Illustrator to do the hole Manufacturing documents

Export DXF file to send to laser cutting machine

1. 3D part My final project has a structural part that holds a stepper motor. I hope it can be manufactured by 3D printing, so it is logical to design this model for this assignment.

Because this part is a relatively thin shell-shaped part, it is more suitable to be completed by additive manufacturing (3D printing is used here). If it is manufactured by subtractive manufacturing, a lot of material will be wasted.

First, draw a rectangular draft based on the position of the fixed screws. This rectangle needs to be 2cm larger than the length and width of the motor. It is enough to arrange 4 screw ports.

Use the drilling tool to create a new circular hole with a diameter of 4mm

Make 4 screw holes in the same way

Then you need to make a cavity to fix the motor. First measure the size of the motor.

Make a sketch according to the size of the motor and then extrude it

According to the height of the motor 39.4mm, the extrusion distance is set to 40mm, leaving a little margin.

Make another hole at the top to expose the rotating shaft of the motor.

The top needs to be fixed with screws and 4 holes are opened (all 3mm screws are used here, so the openings are set to 4mm)

Finally, there is one thing I almost forgot, which is the motor interface.

Same processing steps, slice, import into 3D printer, start printing

I don’t know the reason, but the printing was in a chaotic state at the end. Later, I asked the administrator and he said that it might be caused by the temperature of the discharge port not being high enough,

so I tried again. The temperature was the same the second time, but the temperature was the same the second time. It worked the second time. As shown below

what hasn’t worked?

What frustrated me the most was the production and testing of the PCB, which took me a lot of time and almost broke me down.

I soldered the male pins to the 4 interfaces of the stepper motor and connected them to the PCB board according to the motor driver instructions (as shown below).

The picture comes from the instruction manual provided by the motor drive merchant

I was ready, turned on the power, and found that the motor moved once, then stopped, and the motor driver chip was still smoking. I immediately disconnected the power and found that the chip had been burned.

The inspection found that: 1. The stepper motor driver did not have a heat sink; 2. The four lines of the motor were connected in the wrong order; resulting in a short circuit or error in the circuit, causing the chip to overheat and burn out.

So I need to make the PCB again

start from schematic.

Before this, the tutor suggested that we can do experimental tests with strips first, and then manufacture PCB boards.

Started a long testing journey

I started using a breadboard to test how the motor works properly

At the same time I also restructured the schematic

and soldering

After the test was completed, it was discovered that there was a new method that did not require the use of the RTC module, so the entire circuit was also modified, and this board could no longer be used. Until now, many PCB boards have been sacrificed. The following is Their collection, these PCB boards really took me too much time to make

and this is the final test demo:

Next I need to integrate this feasible demo into a PCB board.

1. schematic The following are the components I will use

Connect all pins according to the demo wiring method to get the final schematic

1. PCB board

Switch to PCB board design and connect all the prompted connections with actual circuits. We get the following circuit diagram, and then we use “Check-Design Rule Check” in the menu bar to test whether there is a problem with the PCB board.

then Convert Gerber to PNG & Convert PNG to G-code

This conversion method was mentioned in week8, you can see the detailed operation there.

1. PCB manufacturing Then I can finally start manufacturing again.

Then quickly complete the welding,

finally can jump to the next part.

what questions need to be resolved?

The manufacturing of PCB boards was scrapped in the first 5-6 times, and the problems that occurred each time were different. This problem consumed a lot of my energy and time, and it was something that urgently needed to be solved.

what will happen when?

Every time I go through the process of schematic drawing - PCB board drawing - CNC manufacturing - welding PCB board, at this time, when power is turned on for testing, various problems will always occur, causing the board to burn out or not working.

what have I learned?

The most profound experience is: before making a board, you must use a bread version to make a test version. After all the circuit connections are adjusted and the effect we want is achieved, we can truly enter the production workflow of the integrated PCB board.