Fab Academy

Miguel Lourenco

 


 
 
 

 
Computer Controlled Machining

While waiting for CNC Router operationality in FABLAB Coimbra, we worked in joint project. Design and machining of three chairs that together make a sofa, when they are aligned.

 

Final assembled wooden chair perfomed with Laser Cutter.

 

CNC Router

Finally, the CNC router that is being designed, and assembled, in Fab Coimbra is ready to perform 2d cutting, that is enough to make 2D cutting cycles for my MDF wooden hanger for jackets.

The working table dimensions are, approximatly:

(X= 1 m; Y= 2,5 m; Z= 0,5 m)

 

 

I used two MDF boards that fit each other. The 3d model can be seen on the right side of this page.

After 3D CAD modelling and 3D CAD tests to trial fits (part 1 and part 2), I exported .dxf files to CNC Router controlling software (Galaad 3).

The board parts with 16 mm of thickness will be fitted each other without glue or bolts.

 

Computer-controlled machining:

Adjust model and dimensions (490 mm X 1210 mm) for 2D cutting cycles.

 

 

Selecting tools and cutting parameters:

tool: cylindrical type, 8 mm diameter and 3 flutes.

cutting speed: 5 mm/s

Spindle rpm: adjust for "good cutting sound" and no burning material/smoke cutter.

 

 

 

We have to fix the board with tighten grippers because the great cutting forces that are applied to the material, and ensure its horizontality too.

The CNC Router needs better adjustments, we detect some scale issues, especially in Y axis. The model wasn't totally machined in Y axis and it isn't for the wooden dimensions (greater than model). It can be seen in figure above.

Furthermore, I noticed that, even adjusting major feed speeds, like XY 20 mm/s, the real speeds was quite less than this value.

 

 

Still missing to mount the suction system, so I had to use a vacuum cleaner.

Although the equipment is not functioning at 100%, allows running 2d cutting jobs, and we should not forget that it was developed and assembled in the fab lab.

 

Well, the final result is shown just below.

1 2

 

 


 

 
2 3

Chair and Sofa (CAD)

 

 

 

1

Assembled hanger for jackets "Dress"(CAD)

2 3

Parts to fit (CAD)

 

 

 

Cutting parameters (thickness for final pass was 2 mm, not 5)

 

Tool parameters (for the second model part, it wasn't execute drilling cycles)

 

Adjusting feed speeds and workpiece origin.

 

Adjusting workpiece origin.