Greetings.

I am one of the Fab Fellows who recently joined up with SSBx. I am currently finishing a masters degree in Architecture, so I have strong interests in fabrication, design, and sustainability. My experience in fabrication was with different machines and programs than what the FabLab uses, so I have been spending some time getting used to the equipment.

This week I tested out the ShopBot’s (CNC router) surface milling capabilities. Basically, it can be used as a big cutter that will cut out shapes and drill holes, or it can be used to mill fully 3D objects and surfaces. There are several steps to the surface milling process, but it was relatively simple to get a small test part milled.

Here’s a quick outline of the process I used:

First I used a 3D cad/cam program to model the part on a computer. In Rhinoceros I created a warped plane with a raised ‘SSBx’ since I know that Rhino is good at exporting 3D files in file types that can be understood by other programs.

Next I had to take the file into Mill Wizard, which is the program that lays out the paths that the tool will follow in a language that the machine can understand. During this process I had to make decisions regarding the level of precision I wanted versus the amount of time milling would take. This trade off is based on the size of the mill bit and how far you want it to step over on each pass of the bit back and forth. The smaller the step over, the greater the precision (its similar in concept to approximating the area of a shape or curve in calculus).

I also decided to create a roughing pass and a finishing pass to speed up the milling process. The roughing pass uses a larger bit so that it can remove material faster. It is calculated so that it leaves a small amount of material to then be removed by the finishing pass, which uses a smaller bit and very tiny step over to give finer detail.

After that, all I had to do was load the file into the ShopBot software, set up the router, then hit start. Two hours later, I had a beautifully milled surface. Besides making 3D parts and irregular geometries easy to fabricate, surface milling also works great for making molds.

The focus of my fellowship will be using the ShopBot CNC router and other tools to recycle wood pallets into furniture and possibly installations. I am tentatively calling my project “6 Months, 6 Designs” where each month I create, test, and fabricate a more ambitious design. My first design challenge will be park benches.

More about that coming soon…

-Nathan