Using a jig saw, cut four holes in
the mirror box back for cooling. Three of these holes need to be 3 1/2"
in
diameter, at 120 degree intervals, at 5" radius from the
center. We also want a 3 1/2" hole cut at the center of the back
plate. See the picture of the back plate under mirror box
construction above. Notice that these cooling holes are
located 180 degrees through the center from the mirror cell
columnating screws.
We now need to drill 6 holes in the
top that will hold the truss tubes. See the picture of the mirror
box under mirror box construction above. The trusses are
firmly attached to the mirror box by friction, caused by bending the
trusses as they attach to the secondary cage. These holes will go
completely through the 1" top of the mirror box. Drill pilot
holes, 5/8" from the edge of the main mirror
hole. Make these holes 1" off of the center of three
points, 120 degrees apart. Notice that one of the three sets is
directly at the back of the mirror box. Then, cut these holes to
be 3/4" in
size with a normal drill bit or a forsner bit.
Cut small pieces of wood, maybe 1 1/2"
in diameter. Glue these pieces over the truss holes, from the
inside. This now defines how far the trusses can go into the
truss holes.
We now want to place the screws that
will be used to hold the mirror cover. See the picture of the
mirror box under mirror box construction above. Drill
holes for three screws, 120" apart, 3/8" from the edge of the
primary mirror hole. Notice that these holes are centered between
the LARGER spaces between trusses. Screw the screws into these
holes. Cut holes into the mirror cover, that will allow the screw
heads to pass over. Then, cut or sand the mirror cover so
that it can rotate slightly, binding against the screws. You will
notice that I am doing this in the picture.