Today, I am going to be discussing the process I went through in creating a frying pan designed for an 18 inch doll using a 3-axes CNC. Using this same process, you should be able to create many different types of pans. I will start with how I made the cad file, and then I will talk about how I set up the piece of wood and the G-code (CNC computer language) for the carve.
Be sure to view the video!
Step 1: Create the Cad File
To create this CAD model I used a few steps.
1. I started by creating a loft operation. A loft is a type of operation where a solid model is created by connecting the points of two different sketches together (see the first picture). In this case, the two sketches are the profile of the top and the bottom of the sketch.
2. Next, I use a shell operation on the top of the pan. A shell operation carves out the solid piece by removing all the material except in a small margin by the outside wall (picture two)
3. Next, I create the handle. This is done by using a few extrusion operations. An extrusion is an operation where we take a 2-D sketch and pull it into 3d. I first draw a square out aways from the side of the pan. This will become the cross-section of the handle. I then extrude this square to meet the edge of the pot in one direction, and a set distance in the other direction (picture three).
4. Now, I use the extrusion operation a few more times to cut details into the handle. I round the end and cut a taper in the bottom .
5. Last, I add fillets (curved edges) to the handle, bottom, and wherever I believe it looks better, and finish the file.
Step 2: Make the G-Code
Now, we have the fun part: creating the g-code. G-code is the set of instructions a CNC receives to make the project, and it essentially controls the movement of the spindle. The programs which make this code are called CAM programs. The process of CAM can almost universally be broken down into 2 steps: first, a fast roughing operation, and second, a slower finishing operation. How you create this code is up to you. Paid and free options exist, and both have strengths and weaknesses. Since this is a two sided CNC operation, I will need to have 2 different G-code files; a back side and the front side. When machining these two different parts, I will need to make sure that the starting point (or 0,0,0 point of the CNC) is the same. I use the center of the pot as my starting point.
Step 3: Set Up the Stock
Since I am using the center point as the starting point, I will need to find this point on both sides of the piece of wood (or stock) that I will use. I do this by drawing a line from corner to corner on each side, and setting my start point as the point the lines cross. I also need to make sure the the stock does not get twisted when I flip the piece over. To prevent this, I create pegs on the center of the short sizes of the stock. That way, when I flip the piece, I can be sure nothing gets twisted.
Step 4: Let the Chips Fly
Now I let the CNC do its job..... Let the dance begin!