The cut process

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  The cut process:

After setup and adjustment of your machine with the help of the CNC menu, the cut proceeds with the following operations:

  • Check up of the timer value (Menu CNC:Timer Tuning). The timer check-up is not necessary if you are using a quartz as timebase (precision remains OK) but allows to verify that the interface board is powered on..
  • Definition of you cut project (Menu Project:Wing Configuration)
  • Dressing up of your block (Menu Cut:Block Shaping)
  • Cut of the block (Menu Cut:Wing Cut)
Project definition: 

To describe the wing shape (or wing fragment), you have to define:

  • The segment length, 
  • the Chords values (root and tip),
  • The Tilt angle, 
  • The Dihedral (take care of differencies between left and ridht wings !)
  • The choice of airfoil section through a file (you can find a wide choice of airfoil sections through Selig Airfoil Database). The choice has to be made twice, for the root and the tip of your wing.
  • The dimensions of leading and trailing edges
  • The skin thickness
  • The positions and dimensions of any spars (wood or composite)
With the wing characteristics, the software will derive from the coordinates tables for the airfoil sections the list of basic commands required by stepper motors. This includes:
  • Scaling : The airfoil section coordinates are multiplied by the chord values (airfoil section coordinates are normalized)
  • Withdrawal of skin thickness
  • Withdrawal of points relative to leading edge, defining new points if required [Not implemented yet]
  • Addition of some points to setup the spar(s) locations
  • Rotation of the section by the desired angle of attack (case of twisted wing)
  • Insertion of clearances for leading and trailing edges
  • Addition of required translation movements in order to setup the wire at the beginning of the wing section
Once the new coordinates are calculated, the software is going to generate the elementary controls for the motors. It will take into account the characteristics of the employed motors (number of steps / 360°), the characteristics of the transmission screws, and the table geometry. These parameters allows to figure out the multiplier coefficient to apply to the coordinates in order to get values in number of steps.