Patrice Rabby wrote in 061118 MMDigest:

> I don't find any information about the position of the two holes
> on the metal bars (to hold them in the frame).
>
> I use alloy bars 30 mm width and 5 mm thickness.

The holes must be on or around the nodal points in the bars, which
is 1/9 of the bars' length from each end.  Also, it is worth bearing
in mind that the cross-section proportions of the bars (you use 30 mm
x 5 mm) determines the harmonic content of the sound.  For instance,
30 mm x10 mm gives a strong quint harmonic to harmonize with pipes in
an organ.  However, if there are no pipes in your instrument, that
consideration is less important.

I hope that helps.
Regards,
John Page, UK