What I did in Week 07

This week covered computer-controlled machining from safety and machine characterization through CAM software setup, toolpath generation, G-code output, real cutting, and final assembly.

Assignments for the week:
  • Group: safety training; test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine.
  • Individual: make (design + mill + assemble) something big (~meter-scale).
  • Extra credit: no fasteners or glue.
  • Extra credit: include curved surfaces.

Week 07 assignments and links

These are the pages and resources associated with my Week 07 work.

Group Assignment · Safety Training

Before operating the CNC machine, all team members completed the mandatory safety training covering PPE, emergency procedures, and machine safety protocols.

1

Personal Protective Equipment (PPE)

  • Safety glasses or face shields against flying particles and sparks.
  • Heat-resistant gloves for handling hot materials and operating the machine.
  • Ear protection in high-noise environments.
  • Fire-resistant clothing if welding operations are involved.

We used the same plastic safety glasses from Week 04:

[ Image: Safety Eyeglasses — image1.jpeg ]

And a dust mask to protect against inhalation:

[ Image: Dust Mask — image2.jpeg ]
2

Emergency Procedures

  • All operators trained on the location and use of emergency stops.
  • First aid procedures reviewed for burns, cuts, and other potential injuries.
  • Fire evacuation routes and procedures regularly reviewed.
3

Machine Safety

  • Understand all machine controls and their functions before operating.
  • Never bypass any safety devices or guards on the machine.
  • Ensure the machine is properly grounded at all times.

Machine Setup

Step-by-step procedure followed to prepare the CNC machine before cutting.

1

This is the CNC machine used for the assignment:

[ Image: CNC Machine — image3.jpeg ]
2

Fix the board on the machine bed tightly. Insufficient fixturing causes the board to shift position mid-cut, ruining the piece.

[ Image: Board Fixturing — image2.jpeg ]
3

Debug the machine and upload the test file before any real cutting.

4

Return the machine to its mechanical origin. Set manual speed to 15,000 mm/min to locate the zero point.

[ Image: Setting Zero Point — image4.jpeg ]
5

Testing parameters: 5,000 mm/min feed rate with an 8 mm milling cutter. Calculated tolerance: 0.1 mm — to be set in software in the next step.

6

Board dimensions used in the lab: 1.2 m × 2.4 m × 18.6 mm plywood.

7

Return the machine to the zero point. Setup complete — ready for G-code generation.

CAM Workflow · MasterCAM X6

Toolpath and G-code generation was done in MasterCAM X6, following the steps below.

1

Export DXF files. The instructor combined all furniture designs from every team member into a single layout file.

[ Image: DXF Export View 1 — image5.jpeg ]
[ Image: DXF Export View 2 — image6.jpeg ]
2

Import all DXF files into AutoCAD for layout arrangement.

Color coding: Red represents the CNC board boundary (1,200 mm × 2,400 mm); green represents each team member's cut files. Layers are merged after placement — color distinction helps separate the board outline from the parts to be cut.
3

Create the cutting tool: 8 mm diameter end mill. Parameters set:

  • Rotational speed: 15,000 mm/min
  • Feed rate: 5,000 mm/min
  • Plunge rate: 500 mm/min
  • Safety height: 50 mm
  • Feed plunge position: 3.0
  • Depth: 18 mm
  • Cutting depth: default
[ Image: Tool Diameter Setting — image7.jpeg ]
[ Image: Tool Parameters — image8.jpeg ]

Tolerance tested at 0.1 mm — set in software:

[ Image: Tolerance Setting — image9.jpeg ]
4

Set safe height to 50 mm (Z raises to this height after each cut) and board thickness to 18 mm.

[ Image: Safe Height and Board Thickness — image10.jpeg ]
5

Press R to preview the toolpath. If the tool direction is incorrect, reverse the series direction of the affected contour.

[ Image: Incorrect Tool Direction — image11.jpeg ]
[ Image: Tool Direction Issue — image12.jpeg ]
6

Continue simulating until all paths are correct:

[ Image: Correct Path Simulation — image13.jpeg ]
7

Set the number of milling passes to 2.5.

[ Image: Milling Passes Setting — image14.jpeg ]
Speeds and feeds: determine optimal cutting parameters based on material type and thickness. Use manufacturer guidelines or CAM software to calculate appropriate values. For wood/plywood, climb milling improves surface finish and extends tool life.
8

Final simulated toolpaths for all parts:

[ Image: Final Simulation Path 1 — image15.jpeg ]
[ Image: Final Simulation Path 2 — image16.jpeg ]
Toolpath best practices:
  • Design paths to minimize tool wear and avoid excessive heat buildup.
  • Use climb milling for better finish and longer tool life.
  • Check all paths in simulation to avoid collisions before sending to machine.
9

Simulate all files together:

[ Image: All Files Simulation — image17.jpeg ]
Watch out for broken contours: open paths (disconnected geometry) may not be recognized by the machine. All curves must be fully closed at design time.
[ Image: Broken Path Issue — image18.jpeg ]
10

Confirm all paths are correct and export the G-code file:

[ Image: G-code Output — image19.jpeg ]

Real Cutting

With the board fixed and the zero point confirmed, the G-code was loaded and cutting began. Noise levels were very high — noise-cancelling headphones are recommended.

[ Image: Zero Point Setup — image20.jpeg ]
[ Image: Cutting in Progress 1 — image21.jpeg ]
[ Image: Cutting in Progress 2 — image22.jpeg ]

Results after cutting:

[ Image: Cut Results — image23.jpeg ]

Each team member assembled their own design:

[ Image: Assembly Process — image24.jpeg ]
Done! All pieces cut cleanly and assembled successfully using the characterized parameters.

Bonus · Chen Xin's Rocking Chair

Congratulations! Team member Chen Xin welcomed his second baby in July and designed this rocking chair for his child — a perfect example of applying digital fabrication to a personal project.
[ Image: Chen Xin's Rocking Chair Design — image25.jpeg ]

Next step

With CNC machining characterized and a meter-scale piece successfully produced, the next weeks will integrate these large-scale fabrication skills with electronics and embedded systems toward the final project.