Dear Flash & Brian,

Scribing & flexing works perfectly well on any thin metal. The harder
the alloy, the better.

Orientation is of little importance. On thick airfoils such as NACA
0024 ( used for struts, etc ), the curvature exceeds 90 degrees,
making the matter of grain moot.

The scriber appears to make more difference than the grain in that a
#11 scalpel works better than a machinist's scriber. Or perhaps it is
the surface on which you lay the metal for scribing. While it works
okay using a book or piece of wood, as a general rulle, it works best
if the scribing is done atop a metal surface.

-R.S.Hoover