Charlotte - FabLab de Charleroi Fab Academy website
  • Facebook
  • Instagram
  • Gitlab

7. Computer-Controlled Machining

Hero shot

...

Group assignment

It's time to get to know the CNC. We have a Mekanika model.

...

In order to do that, we've created a simple square part using the machine's various cutting and engraving options:

  • a round hole
  • a rectangular pocket
  • a notch with dogbones for nesting
  • bridges to prevent the part from jumping off the table

Part design

We used Freecad to create a parametric square part using spreadsheets.

The parameterized parts are :

  • the side of the square
  • the part thickness
  • the radius of the fillets
  • the round hole diameter
  • the X position of the round hole
  • the Y position of the round hole
  • the kerf
  • the notch length
  • the notch width
  • the rectangular pocket length
  • the rectangular pocket width
  • the rectangular pocket thickness
  • the X position of the rectangular pocket
  • the Y position of the rectangular pocket
Easy part construction

To avoid drawing the different parts by manually entering each measurement, we've used the symmetry (horizontal, vertical) and constraint (horizontal, vertical, radius, diameter) options.

...

The symmetry and constraint steps must be performed one by one to avoid errors.

Once all the parts have been constrained, they are linked to the parametric table.

...

An error may occur from time to time. The solution is to remove redundant constraints displayed in the sidebar.

...

When the part design is ready, all lines and points are green and the message "fully constrained" appears in the sidebar.

...
Preparing the file

Once the object has been created, we need to prepare the file so that we can start working on the CNC.

To do this, we must first register the various mills and their parameters in Freecad.

... ...

To get the right cutting parameters and avoid complicated calculation, we had 2 options :

  • Sylvain Denis' online calculator (great job, thanks ! :D ) already adapted for the Mekanika
  • Dominique Lachiver's online calculator
... S. Denis - CNC Calculator
... D. Lachiver - CNC Calculator

Using the CNC

Safety

Safety is essential in the Fab Lab (even more with this kind of machine). The first step is to have and use personal protective equipment (e.g. ear muffs, goggles, dust mask, and gloves especially for moving the boards).

...

It is also important to unplug the spindle before changing the tool on the machine !


Changing the tool

First step is to change the tool and make sure that it is correctly fixed.


Think about preparing the right pieces (in our case, the mill was to big) !


Placing the board

Object cut with the CNC

Link to our Group page


Individual assignment

CNC Project

...
Design

Mill

Assemble


Files and resources

My files

  • Freecad : Square part for CNC test
  • ...

Resources

  • Dominique Lachiver website : interesting website IN FRENCH (created by a retired teacher) to learn digital manufacturing
  • Our group page

Menu

  • Homepage
  • Assignments
  • Week per week
    • 1. Project Management
    • 2. Computer Aided Design
    • 3. Computer Controlled Cutting
    • 4. Electronics Production
    • 5. 3D Scanning And Printing
    • 6. Embedded Programming
    • 7. Computer Controlled Machining
    • 8. Electronics Design
    • 9. Output Devices
    • 10. Mechanical Design And Machine Design
    • 11. Input Devices
    • 12. Molding and Casting
    • 13. Networking And Communications
    • 14. Interface And Application Programming
    • 15. Wildcard Week
    • 16. Applications And Implications
    • 17. Invention, Intellectual Property And Income
    • 18. Project Development
  • Final Project
  • About Me

© Charlotte - FabLab de Charleroi. Fab Academy 2024. All rights reserved. Design: HTML5 UP.