Frame is simply too flexible/unstable for tension mount of screen
Discussion: I think the
main cause of the unstable frame is simply that it is made out of
a plastic in such dimensions that some flexing is inevitable. This
inherent material instability is exacerbated by the fact that the
rails and corner fittings are held together with only 2 screws
each, rather than six screws as is evident from the design of the
Additionally, the clamps also
tend to flex excessively due to 1) construction in plastic, and 2)
excessive spans between mounting screws. Clamp flexing results in
the screen stack actually only being retained by smaller
intermittent static contact areas, rather than a uniform static
contact "strip" along the entire clamp/frame bearing
Possible Courses of Action:
1) Employ necessary measures to
increase the rigidity of the frame such that the screen stack can
be securely clamped in on all sides under tension to maintain a
uni-planar screen surface.
2) Do nothing. Accept the
current results as "acceptable", and continue to use a
gravity/free-floating screen assembly.
3) Refine the gravity/float
method to achieve near zero lenticular distortion by utilizing the
a) Increase frame rigidity
with the installation of 16 (4x4) additional screws in the
corner fitting to frame rail joints. Frame will be secured in a
truing fixture while additional hardware is installed to insure
the frame is square.
b) Add at least two additional
mounting points to the top clamp/frame rail to spread the
suspension loading of the screen stack across the entire width
of the stack.
c) Analyze the gasketting
requirements for the sides and bottom of the frame to 1)
maintain a free float, 2) limit the fore/aft travel of the
screen stack to a minimum, and 3) encourage maximum contact
between the fresnel and lenticular screen elements.
Chosen course of action: Number
3.... obviously. Number 1 would require a completely new
build of the frame to achieve the necessary rigidity; the plastic
frame as designed probably could not be reinforced enough (at
least economically) to accomplish a tension mount. While I am
happy with the improvement achieved thusfar, I am NOT satisfied.
Not when it appears relatively certain that near perfect results
can be achieved with a little more time and effort.
I will continue to refine this
procedure, and will re-write it in final form once the entire
procedure is complete and proven. The re-write will exclude the
"misadventures" and simply present a step-by-step
procedure to get from Point A to Point B.