For this week, we needed to learn how to use the CNC (computational numerical controls) machine. As a result, the whole file-prep phase was the initial stage.

There are two really good online CNC software generators that you can use. The first is makercam.com and the second is “easelinventables”. The latter is better in my opinion because it allows you the see the final product in its 3-D form as you go along. The key here is to make sure to specify the safety height that the drillbit will hover over the piece and also the width of each pass.

For us, we wanted to build concentric circles layered on top of one another and so it would be cool if we found a drillbit exactly the width of each circular ring.

After prepping the file and generating what’s called “g-code” which is machine code that tells the CNC how to move, we went into the CNC machine room.

The interface on the computer for the particular machine was easy to use because the program set-up looked very similar to that of the plasma cutter.

Again, I like to point out the crucial aspects of this process. Once you enter the software, you will have to first make sure that the piece is within the quadrant of interest. The machine starts at the bottom left when looking at it from where the computer is. This is ESPECIALLY important because if the material that you want to cut the piece from is not big enough then it will translate the piece to a certain length in any direction. This is because when you import the g code, the position relative to the origin when you first created not longer translates through into the CNC software.

To help speed up the process, you can adjust the “plunge rate” which is how fast and how far down each pass moves and also the feed rate which is basically how fast the drill cuts or mills the material. However, be especially careful about this since harder materials can damage the drill at fast feed and plunge rates.

This was the result……So my teammate and I were at first puzzled at this because it was supposed to be layered. But we then found that the culprit was that the specified drill bit when we first made it did not correspond to the actual sizing of the drillbit. This could have been easily remedied by having the drill make another profile cut offset by the width of the drill around each ring. Moving forward this is definitely something to note.

Andddddd the final product.

In the end, we used and exacto knife to cut the small foamy pieces off. There is not much post processing you can do with foam, but here it is!