7. Computer controlled machining¶

Group assignment:¶

Complete your lab’s safety training
Test runout, alignment, fixturing, speeds, feeds, materials and toolpaths for your machine
Document your work to the group work page and reflect on your individual page what you learned

To see our group assignment click here

Individual assignment:¶

Make (design+mill+assemble) something big(~meter-scale)
extra credit: don’t use fasteners or glue
extra credit: include curved surfaces.

For this project, we’ve decided to make a stool. We’ll be using the ShopBot Alpha 96 digital milling machine with MDF.

STOOL DESIGN¶

To begin our work, we designed our stool using onshape, an online software package.

Once the modeling was complete, we exported our files in .DXF format.

Toolpath generation with V-carve¶

To generate the toolpaths, we proceeded as follows:

open the dxf file with v-carve
enter the working dimensions of our Shopbot milling machine and deactivate the offset as shown below

We selected all the interior cutout contours in our design and clicked on “create fillets” to generate the Dog-bone as shown below.

For the toolpath, we first generated the toolpath for cutting as shown below.

For text
For the text we have directly used the v-cave software as follows:

To begin, we’ll select the text tool

1: choosing a font
2: writing in the text area

The text is presented in this way, so we can arrange it as we wish.

We now move on to the generation of engraving tool paths, as shown below.

Once the paths have been generated, we proceeded to record them as shown below. We started by tracing the path for cutting and then for engraving, as we won’t be using the same tools.

MACHINING¶

The ShopBot CNC is a computer-controlled machine tool used for milling, cutting and engraving on a variety of materials. It has a sturdy steel or aluminum structure and uses stepper motors or servomotors for precise movements on three main axes (X, Y, Z). Models vary in work area size and are equipped with high-speed spindles (up to 24,000 RPM). Commonly used software includes VCarve Pro and Aspire. Accessories such as dust collection systems and vacuum tables are available to enhance its capabilities. We used two tools to machine our stool, as shown below.

Getting started
Secure your board with spikes to prevent the wood from shifting during cutting and causing damage.

Open the ShopBot software on your computer

On the software, select your file, then click on Cut Part.
Activate the tool by pressing the button circled in red

Activate the depourser by lifting the crank as shown in the image below.

Tools

The one on the left for engraving and the one on the right for cutting.

After securing the MDF panel and mounting the cutting tool, we’ll switch on the machine and get started.

Define your X/Y, inspired by our work in week 04. select the button that looks like a miniature version of the yellow keyboard. Use the arrow buttons on the keyboard to set the bit to match the XY reference position defined in the file configuration options.