Rest setup for the trolleys:

You can choose between two rest positions for the XY trolleys:

• They can be setup to rest in front of your table, just near the operator. This will give you a better visibility over your foam block, especially if your table is pushed against a wall. The cut operation will proceed from front to rear (figure Position en avant)

• On the contrary, they can be setup to rest at the rear of the table. This provides a better protection for Y axis against inexpected shocks. The cut operation then proceed from rear to front. The hereafter figure shows this configuration (Position en arrière).

The only difference lay in the rotation direction for the X axis stepper motors. In order to invert the rotation direction, refer to the CNCnet website, motor wiring page (usually, inverting one winding of the motor). In both cases (whatever the configuration), the drawing of top view of the table and  foam block will be similar in the software.

Foam block position.

The position of the foam block is linked to the wing geometry: 

• Case 1:  If the wing swing is low (which means that difference between root and tip chords is low), then the block will be setup centered on the Z axis (equidistant of each trolley).  In this case, there should not be any cut difficulty.

• Case 2: Should the swing be high, the foam block cannot be centered because the X displacement (left on the figure) is too small to be precise enough. In some cases, the Xg displacement may even become null (refer to the fixed point foam cutting method), or the Xd displacement on the other trolley may exhaust the capability of the table.

• Case 3: In order to solve this particular difficulty (which arise often enough, for instance while cutting a Dornier-type tip), three options (presented hereafter) are possible:
3.a The block slipped to the tip side (small chord: figure 3 'Positionnement sur le saumon').  The only limitation is the size of the tip itself. One may also encounter problem due to the size of the displacement on the right X axis (Xd), versus capacity of the table.

3.b The block slipped to the root chord side (larger chord: figure 4 'Positionnement sur l'emplanture'). In this case, the software should invert the airfoil section with respect to the A point.

 3.c Last option is to mechanically shorten the table, if your design allows for this. By bringing closer X axis, the projected displacements on both axis remains within acceptable limits (figure 5)

Conclusion: For difficult cases, choose the block location as a function of the wing shape, your table capabilities and the software !