Computer-Controlled Machining

In this project we learn how to use the giant CNC machine and how to make furniture.

Flat pack album Shelf

I decided to design a desktop shelf for Music albums and CDs. The idea is to have every part machined out with the large CNC machine in the Fab Lab. The parts are to be assembled together without screws, hence I will need to implement fingers for the parts to slot into each other. The material used will be a 15mm thick wood.

1. Album shelf design

I start off with creating User Parameters. The few important parameters is the wood thickness and the tool diameter

I first create a new component for the base, sketched and extruded it with thickness of the wood thickness parameter.

I create a sketch plane on the surface and extrude cut hole slots.

Next the back wall: I created a new component, created a sketch plane on the face of the slot. To create the fingers to connect to the base I used combine cut.

I repeated the procedure to create the right side. I then sketched and extrude cut out fingers on the side.

For the left side I create a new component and extrude the right side with offset such that it extrudes at the other side.

I then create the finger tabs with combine cutting.

To create a mid shelf I created a new component and create an offset plane to the height I want. I then sketch and extrude.

I then sketch and extrude cut finger tabs, following by combine cutting the walls.

I added a few more parts and I get this:

After getting the main shelf done, I added features and gave the parts a wood texture.

2. Creating dog bones

It is important to note that the drill bit used to cut the CNC has a diameter and would normally be unable to cut out right angles. This can cause joints to not fit together properly. Hence we will need to create fillets in each slot hole, such that it looks like a dogbone.

First install the FUSION 360 Dog bone addin: its as simple as going to the website and downloading the self extracting file. The feature looks like this:

I will need to add dogbones to every slot hole, to start I hide all the parts except the part im working on, then slowly go down the components.

  1. Click on Dog bone
  2. Select the face you want to add Dog bones
  3. Set the tool diameter (here I used my User parameter)
  4. Hit "Ok"

The fillets will be created at the corners.

If there are hole features that are not slots, after selecting the face you can select "DogBone Edges" to deselect edges or select edges.

Here is how the finger joints would now look:

Next I save the parts in DXF and used VCarvePro in the workshop to generate the gcode.

First is to measure the wood material used and specify it in the software. then bring out the parts and arrange them to fit onto the piece.

We then add tabs on the parts to ensure they do not move during the cutting process. The cut depth is a few milimeters more than the actual wood so the machine will cut through all the way.

Secure the wood with screws, set the zero points and press start.

Next we cut off the tabs with a chisel, used a deburring tool to remove the burrs at the edges and sand the sides smooth.

The parts are a tight fit and I had to use a mallet to fit them into place.

Here you can see the dogbones.

After hours of knocking the parts together, the cabinet is done!


File download: shelf.f3d, dxf files.