WEEK 4: CNC Machine

This week we learnt how to use CNC Machining. Our assigment was to create a 3D model and cut out it on small block of foam with dimensions of 70mm x 100mm x 40mm. To complete the assigment we used machine Roland MDX40.

3D DESIGN

To create a 3D model I used 123D Design. I decided to draw something simple but as you know all what seems to be easy later on could have some pitfalls :) Nevertheless my model was just Face on a cube.

Below you can see how to create a 3D Face step by step:
1. Create a box with same dimensions as foam
2. Use Modify - Shell to make cube empty inside with borders 5 mm
3. As we don't need completely empty box so now we need to fill our box: Modify - press/pull but the 8 mm from the top should stay empty for our drawing (8 mm because our tool for cutting is 10 mm).Afterwards, it is better to measure.
4. To make nice borders - use Fillet with radius 9 mm

5. Make a Sketch on the top

6. Extrude all objects. I used 8 mm and 6 mm. Also I used Fillet or Chamfer to avoid angle 90.


7. Export file in STL to continue to work with it in software Autodesk Fusion 360

CNC Machine

Before to start milling I used Fusion 360 to prepare the object for cutting:
1. Upload object
2. Select workspace MODEL
3. Select Body - MeshBody - right click - Mesh to BRep. After I pressed Mesh to BRep was appeared an error:

The number of facets in the mesh must be relatively small (10,000) otherwise it takes a long time to convert. To solve this error I used another Autodesk software Meshmixer :
- Import STL file
- choose in left toolbar Select - click on the object - Select Modify - Select All - Edit - Reduce - now you can choose several options how to reduce facets, I reduced by percentage. As high percentages as less facets the object has

4.When I had less than 10k facets, I uploaded the model in Fusion 360 and Mesh to BRep once again

5. As you can see I needed to move my object: Modify - Move (or press M). Also I measured my model: Inspect - Measure and after that I had to Scale it by factor 0.1

6. Now object ready for milling. Switch workspace to CAM and press Setup to set up the origin point:
- Operational Type - Milling
- Orientation - Select Z axis/plane & X axis
- Set up Z and X axis
- In Stock set up everything to 0

7. Choose a milling strategy Adaptive Cleaning

8. Set up next settings:
- Select tool - I used Flat 3mm
- Coolant: Disabled
- Spindle speed - 10,000
Now go to passes:
- Tolerance - 0.1 mm
- Max Roughing Stepdown - 9 mm
- Fine Stepdown - 0.3 mm

9. When you press OK the program starts to simulate the milling process to make sure that will be no collisions

10. Before to start cutting, safe object as G code: choose Post process then choose right machine and press OK

11. Open RolandVPannel, set XZY Origin then estimate origin point by moving a head of machine

12. Fianlly, click on cut and choose your G-code

Conclusion: to create a 3D model I spent less then 2 hours, to implement appropriate features before printing in FUSION 360 took near 2 hours (because I needed to improve my model by using one extra software Meshmixer), to cut the model - 30 min

Download a 3D models you can here:
FACE