VIII: CNC Milling

I.CNC Machine

In the class, the professor shows us a demo for CNC machining and asks us to model one before the lab time. Someone may confused about what is CNC machining. It’s like drilling, laser cutter, and 3D printer. The reason is that it uses drills to cut the materials in three dimensions. Let’s see my model and how the CNC machine works.

Model

CLICK TO DOWNLOAD MY MODEL!

CNC Machine

Project: Hammer

Problem:

Because there are some features on my hammer, they requires really delicate drilling. That means that it will take a long time to make it but I only have limited time. If you have time to do that, you need to change to small drill and smaller stepover. The diameter of the drill I used is even bigger than the width of my pattern on the hammer so that the machine can only try to cut one pattern. You can see the difference between my model and project.

Another problem is similar to the former one. I used to build a more complicated model that even have a sign of flash and the names of Jonathan and me on the surface of the hammer. But when I show it to Nathan, he told me that it’s may be a little tough for CNC machine. On one hand, it’s hard for a drill with large diameter to cut letters which are very small. On the other hand, because there is a vacant space at the bottom of my model, I cannot do it with the CNC machine. The reason is that although CNC machine can operate in three dimension, it can only cut from up to down instead of cutting the buttom. As a result, I can only use 3D printer to print it. And some of the letters are still very hard to distinguish even though I use the 3D printer. You could see from the vedio below.

Model

Project: Hammer of Thor

If you love my design,CLICK TO DOWNLOAD IT!

II.Composite

During the class, Rob and Nathan show us the procedures to make a composite and I remember it in my mind. In the lab time, Jonathan and I try to make a composite by ourselves. Here are the procedures.

Procedures:

1. Mix the epoxy with a right mixing ratio.

2. Cover the mold with release layer, saturate fiber layers with epoxy, and lay up over the release layer.

3. Add bleeder and breather.

4.Make a bag, insert the mold in it, and pull vaccum and seal.

5. Cure overnight, wait for the miracle!

Project

After 18 hours waiting and half an hour processing, we finally finish our composite! You could see the shape of hammer from the picture below.

III.Programming

During the assignment review in the last class, Nathan told me that there is a way to run two loops simultanenously with milliseconds instead of delay. That means that I could operate it with only one Arduino so that it’s easier for me to construct the project. In the lab time, I ask Nathan about this problem and he sucessfully help me solve it. Actually it’s very reasonable: you just need to have a new void loop and write your program in another loop, so the two loops could run together.

The program:

void setup() {
  Serial.begin(9600);
  pinMode(3, OUTPUT);
  pinMode(7, OUTPUT);
}

// the loop routine runs over and over again forever:
void loop() {
  controlLED();
  
  int sensorValue = analogRead(A0);
  Serial.println(sensorValue);

  if (sensorValue >= 500) {
    digitalWrite(3, HIGH);
  }
  else {
    digitalWrite(3, LOW);
  }
}

void controlLED() {
  if (millis() % 8000 < 5000) {
    digitalWrite(7, HIGH);
  }
  else {
    digitalWrite(7, LOW);
  }
}

If you love my program,click to download it!

The project:

After using the renewed program, I could make the LED shine routinely and the AnalogRead keep reading simultaneously. As a result, I only need one Arduino, so I transplant the circuit of the LEDs to the other protoboard. Let’s see how they work together.

Also, for the final project, I need two motor to function as pulley to pull the car moving forward. As a result, I find two DC Motor and two logo wheels. Later I drill the wheel to make it fit for the axle of the motor. Fortunately they fit so well. And I also use the hot glue to make them combine more tightly.

Summary

For this class and lab time, I have a chance to operate the CNC Milling for the first time. Although I meet some problems, I improve myself during solving them. Also, I think I take a big step for my final project because I successfully solve the problem of the power of my car. My next step is to make a car and connect it to the pulley to see whether it works or not. There are only two weeks remaining before the presentation for the final project. I need to work harder.