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Norm's calculations:

   1) Calculation of the maximum deflection of a wire due to gravity.

     Max deflection = mass(g) Length(m)
                                   8 Tension(g)

For 50micron dia. Tungsten (Gold-plating is typically 6 microinches of almost identical density)

     Mass = 19.3 g/cm**3 * 3.14159 *(25x10**-4cm)**2 * 40 cm = 0.015g

Tension (g) Deflection (microns)
100 7.5
50 15
30 25



With 50g/per wire the load on the y plane is 32*50g = 1.6 kg

2) Deflection of a rectangular beam supported at the ends and loaded in the center is:
Deflection =                         F (load)      L**3                        
                      48 E(modulus of elasticity) I (moment of Inertia)

I = (base * height**3 )/12

For our current design with Ertalyte

     E = 460 kpsi
     I = 0.375" (2.75")**3 / 12

Complete load at the center (extreme upper estimate):
     Deflection less than 24 microns


     Based on this I believe that the frame is sufficient and that pre-stressing is not required.