CNC machine session shredding wood now

This week we should lear how to use the CNC router and get in touch with subtractive modeling. I'm really looking forward to this session because I've never used this technique before.

This is the machine I used for the assignment. It was build by my dad in 2016. The idea to build this machine was pushed by the stories I told my dad about what I experienced in our FabLab. He was thrilled about the whole idea about in house fabrication so he built this one. It is based on an Arduino Uno with a CNC shield.

Preparations setup the model

Software I used my toolkit

Build simple demo unit 3D it together

For this session I decide to build a simple model that consist of a line of text that is above the surface and one that is below the surface like an engraving. Everything is framed in a triangle shaped line.

Similar as in week 3 we create the object with a sketch first and extrude the areas. It is also able to generate text in the sketches and extrude it or negative extrude into the object body. When creating my model I heavily used the "rounding corners tool" to form the text and frame.

Computer Aided Manufacturing (CAM) in fusion tool pathfinder

With the finished model I chosen the CAM tool of fusion. The CAM tool is for generating tool paths also known as the way the machine has to move to create the defined object. Fusion here is very powerful because it has multiple strategies when generating such paths. During the setup of the path generation I had to specify the mill I used and the what are the environment variables. The first image show the setup of the different operating layers the machine should use.

When the path is generated, fusion demonstrate it by a blue line on the model that should show how the mill is moving to generate the object. Here is a short video that demonstrate the tool-path simulation for the given cutting strategy.

This are the mills I used for my model. After the first round I changed the tool and went on with the smaller 1mm mill for more detail.

Handling the CNC router in control

After converting the non machine specific tool position data during the post processing into a machine specific one, we generated a .nc file. Now this file can be used in a gcode sender software to send the generated tool path to a CNC router. The software I used was Universal-G-Code-Sender as mentioned above. The benefit of this software is that it is open source and Java based. Because of that I was able to use it on my Macbook. The reason why I mention this is because I realized during my research for software is that most of the software that exist in the internet is for Windows OS only.

Next step is to take a look at the visualize window that the software is able to show. This window show the math that the drill will use when generating the model. It also visualize the drill itself. So here is the chance to check if the start position of the drill to the raw object is right before starting the cut job. In contrast to a 3D printing task the chance to damage the machine, tools or the bench is here more likely. So better double check all positions before start the job.

Now I was able to send the gcode to the machine controller to start the job. The video below show the CNC router during the first layer of its job and also the monitor of the computer to show what the visualization os doing during the run.

I repeated the process with a different path strategy and a smaller mill to cut out the details of the model. The stages of my process is given in the table below.

stage	strategy	tool shape	external diameter
1	free pockets	flat	3mm
2	shape	flat	1mm

When the machine has finished it move back to its homing position and the screen prompt that the job is done.

After two stages with different mills, first 3mm flat head and second 1mm flat head the result looks like this.

The engraved text was first cut in the second stage with the 1mm mill because the text was too fine that the 3mm mill does not fit into the font.

Download section bearing yourself

CNC model in Fusion 360 format	download
CNC model in STEP format	download