This week I was introduced to CNC machining. Computer Numerically-Controlled (CNC) machines are digitally-controlled fabrication machines. CNC machines use computer-aided manufacture (CAM) software to allow CAD models to be fabricated. This integration between the two software systems is called CAD-CAM.

CAM can be: 

  • linear/translational (milling)
  • rotational (turning)
  • can be used for additive (e.g. 3D printing)
  • or subtractive (e.g. milling machine, vinyl cutting, laser cutting, water jet cutting, electron discharge machine and CNC).

After a design is built fully on a CAD software. You’ll then need to define a series of tool paths and export as G-code. G-code (geometric code) is the language the machines use to direct these tool paths. It its a long calculated code.

When writing the G-code, It is Modal, like a switch, so once you press start it will continue until its stopped or finishes cycle.

In the code its done in rows, ’N’ is used to start a new line/movement. Here are the other codes

Movement:

  • G00 rapid transverse (move without cutting)
  • G01 linear interpolation (move in straight line while cutting)

Positioning:

  • G90 is the code for ABSOLUTE POSITIONING
  • G91 is the code for INCREMENTAL POSITIONING 

I was suggested to look at NC viewer witch is a program that will simulate your G-code and will be using it. 

I then went to see it in use. This is the CNC machine I was using.

In the CNC I set up the required details on thickness and positioning of the product. I then drilled the piece inlace. Then I linked the starting point of the cut to where the base material is placed, so it knows where the MDF is. Other considerations is once the item is cut, you have to allow notches for it to not be cut, to stop the cut out piece coming loose, I want it to stay in place. Id then take it out and cut the notches to  free my cut piece.

We made a little mould to go through the CNC process. we started by designing our enitial engraved into a block.

We then went into the manufacture part of Fusion 360 to help with our G-code. We chose our drill size first.

After we then put in our Stock piece of material to cut out of.

With the Stock block inplace we then imput our flight path for the cut out of the stock block, then the implementation of the indent.