CNC Machining Overview

The CNC (Computer Numerical Control) machine used in this lab is a large-format router capable of cutting full-sized wooden sheets using a 6mm cutting tool. It operates through instructions received from a computer, translating CAD designs into toolpaths that direct the cutting head’s movement, speed, and depth. These toolpaths ensure precision and repeatability by controlling the spindle’s rotation (RPM), feed rate (inches per minute), and cut depth.

Functionality Summary:

Receives commands from a computer.
Follows toolpaths derived from CAD designs.
Cuts materials with controlled speed and depth.
Used for manufacturing wooden structures, furniture, and fit-based assemblies.

Video - Full Explanation

The video below showcases how the system works with explanation.

Safety Requirements

Strict safety protocols must be followed when operating the CNC machine:

Eye Protection: Safety glasses must be worn to shield eyes from debris.
Face Mask: Use a face mask to prevent inhalation of fine dust particles.
Clothing: Avoid loose garments, jewelry, or accessories that may get caught.
Work Area Inspection: Check the machine and all tools before starting.
Clean Environment: Keep the machine and surroundings clear of clutter before and after use.
Hearing Protection: Wear ear protection to prevent hearing damage.
Emergency Stop: Be aware of the emergency stop button location.
Operational Distance: Stay a safe distance from the machine while in use.
Handling Materials: Never attempt to remove or adjust material while the machine is active.
Supervision: Machine operation must always be monitored during cutting.

Design Requirements

When designing for CNC cutting:

Maintain at least 20 mm gap between each design part.
Keep designs at least 30 mm away from each sheet corner.
Ensure holes in your design are larger than the drill bit’s diameter (6mm) so they can be cut cleanly.
Select drill bits longer than your material’s thickness for full cuts.
Export files in DXF format for compatibility.
Double-check that the design size suits the tool (e.g., drill bit not larger than the smallest detail).

Debris Management

The CNC machine includes a built-in vacuum system that removes debris generated during cutting. This ensures:

Cleaner work environment.
Improved visibility and safety.
Better cut accuracy and finish.

Importance of Dogbones

Due to the round shape of the cutting tool, internal corners in wooden joints are not naturally square. Adding dogbone fillets to these corners allows parts to fit tightly and accurately in press-fit constructions.

Material Alignment and Sacrificial Sheet

Proper material positioning is crucial to cut accuracy. A sacrificial sheet is placed under the cutting material to:

Prevent damage to the CNC bed.
Allow cuts to go slightly deeper than the material thickness.
Help hold the material in place with screws.

Tips for Alignment:

Max sheet size: 2440 x 1220 x 12 mm (L x W x T).
If the sheet is curved, place the concave side down.
Secure with screws placed within 20 mm of the corners and across the center.

Materials Used

Two materials are commonly available:

Material	Characteristics
MDF (Medium-Density Fiberboard)	- Smooth surface - Easy to machine - Less durable
Plywood	- Layered structure - Stronger and more resilient - Harder to cut cleanly

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