Week 7: Computer Controlled Machining

During the class, I decided to use Rhino and Rhino CAM to complete my assignment, which was a chair. According to the class documentation and consulting past documentation, these are the steps for CNC Milling:

Measure the material. Each board could be slightly different.

Prepare the file, we used RhinoCAM. This is the most time-consuming part.

Prepare the file for the screws. Some boards could be bended so adding additional screws prevents parts from coming off.

Upload files to the cloud.

Fix the material to the table.

Download the files in the machine computer and set the origin (X,Y,Z).

Set the proper end-mill.

Turn on the vacuum.

Set the screws.

Start with the screws-file.

Then, set the screws on the spots.

Run the file with the design.

Vacuum the wood chips.

Take out the cuts, remove the end-mil and put it away.

This is the Model of the chair designed.

Rhino CAM workflow

Select the Post processor. In this case Haas was chosen, which uses the standard G-Code for 3 axis CNC_STEP_BCN. The post processor file extension is nc Machine Setup and Stock Box Machine setup allows co-ordination system, so the file is aligned in a specific way. In the box stock I assigned the LHW of the milling job Select and define the material as wood Set up the work co-ordinates to x:0 y:0 and z:0 so that the co-ordinates of the file match of those to the machine Asign A Tool

1.Prepare the Mill Module

Loading the part model, into RhinoCAM. Select File / Open from the Main Menu bar, or click the Open icon from the Standard bar.

2. Machine Strategy

Based on the size and geometry of the stool, the model will be made from a plywood sheet of 846mm and 340mm and 11.92mm thick. Considering the RhinoCAM instruction manual and the resources of the Fab Lab, a flat end mill, which will be held on the machine table held down by screws.

Select the Post processor. In this case Haas was chosen, which uses the standard G-Code for 3 axis CNC_STEP_BCN. The post processor file extension is nc

Machine Setup and Stock Box

Machine setup allows co-ordination system, so the file is aligned in a specific way.

In the box stock I assigned the LHW of the milling job

Select and define the material as wood

Set up the work co-ordinates to x:0 y:0 and z:0 so that the co-ordinates of the file match of those to the machine

3. Asign A tool

followed the set up from the Fab Academy documentation and set up a flat mill tool as follows above:

Use a 6mm diameter flat mill end

The formoular used to calculate the tool´s feed and speed:: Feed rate = N x CPT x RPM. N = number of flutes CPT = chip load RPM = spindle rotational speed.

This is the tool set up parameters I followed from the class explainations

Using RhinoCAM these were the setting I used to set up the machine

After setting up the milling screws and the file on RhinCAM, I moved on to the CNC machine. The set up was the longest process and most complex. The fablab faculty was there to help set up the end mills. In conclusion, The most difficult part of the project was making sure the file and cutting process was precise, consistently setting up the mill screws. It was enlighting to see how much CNC is used in industry, and that such a heavy duty way of making could be embraced and used to make anything from Plywood.

Download the KiCAD File here