Week07
group assignment • do your lab’s safety training • test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine
# Group Assignment: CNC Machine Characterization
Machine Description¶
The machine used in this assignment is a Scientific Forest CNC Router located at Fab Lab Winam. The machine is a 3-axis CNC router used for machining sheet materials such as plywood, MDF, acrylic, and other non-ferrous materials.
Specifications¶
Machine Type: 3-Axis CNC Router Model: MakerFab 4×8 CNC Router Working Area: 2438 mm × 1219 mm (4 ft × 8 ft) Control Software: Velocity CNC Control Toolpath Software: Velocity CNC Tool Used: 1/4 inch (6.35 mm) Astrolite Coated End Mill Maximum Spindle Speed: Up to 24,000 RPM Collet Type: ER20/ER25 Power Supply: 220V AC
Safety Features¶
- Emergency stop button Kick the emergency button incase of any danger
Ensure you remove dust using vacuum cleaner before using the machine
Safety Training¶
Before operating the machine, I received safety training covering:
- Emergency stop procedures
- Proper use of eye protection
- Hearing protection during machining
- Dust protection using masks
- Safe tool changing procedures
- Material securing methods
- Safe machine startup and shutdown
Runout Test¶
Runout was evaluated by installing a 6 mm endmill and rotating the spindle manually while observing tool movement.
Observation¶
The tool showed minimal visible wobble, indicating acceptable spindle alignment for woodworking applications.
Conclusion¶
No significant spindle runout was observed that would negatively affect machining accuracy.
Alignment Test¶
Machine alignment was evaluated by comparing the dimensions of machined parts against the original CAD design.
| Feature | Designed Dimension | Measured Dimension |
|---|---|---|
| Slot Width | 18 mm | 18.2 mm |
| Tab Width | 18 mm | 17.9 mm |
| Panel Length | 500 mm | 499.8 mm |
Fixturing Test¶
The workpiece was secured using wood screws attached to the spoilboard.
Advantages¶
- Strong workholding
- No material movement during machining
- Suitable for large sheet materials
### Disadvantages
- Leaves holes in waste areas
- Requires careful placement to avoid toolpath collisions
Speeds and Feeds Evaluation¶
The machine was tested while machining plywood using a 6 mm flat endmill.
| Parameter | Value |
|---|---|
| Tool Diameter | 6 mm |
| Spindle Speed | 18,000 RPM |
| Feed Rate | 3000 mm/min |
| Plunge Rate | 1000 mm/min |
| Depth per Pass | 3 mm |
Observations¶
- Smooth cutting action
- No excessive vibration
- Minimal burning
- Good edge finish
Material Evaluation¶
Material tested:
- 18 mm Plywood
Results¶
- Easy to machine
- Good structural strength
- Minor edge tear-out
- Suitable for press-fit assemblies
Toolpath Evaluation¶
Profile Toolpath¶
Used for cutting external geometry.
Advantages:
- Accurate dimensions
- Fast machining
Pocket Toolpath¶
Used for internal material removal.
Advantages:
- Clean internal features
- Consistent depth
Dogbone Features¶
Used to compensate for round cutter geometry in press-fit joints.
Advantages:
- Improved assembly fit
- Reduced post-processing
Conclusions¶
The Scientific Forest CNC router demonstrated good performance for large-scale fabrication. The machine maintained dimensional accuracy within acceptable tolerances and produced clean cuts in plywood using a 6 mm endmill. Screw fixturing proved reliable, while profile and pocket toolpaths produced accurate parts suitable for press-fit construction.
The characterization process improved our understanding of machine capabilities and provided machining parameters that were later applied during individual assignments.