Mirror box and mirror cell construction
The mirror box consists of two internal baffles, and four sides. The
first photo shows the baffles, which give the box stiffness, inserted into
dados in the bottom board. The next photo shows the sides added to the
box, too, as well as the various mounting holes and bolts for the poles and
the mirror cell..
The next view shows the box from the rear, and the bracing on the underside
of the top board which stiffens the box under the focuser. The focuser
is mounted, too. The second photo below shows the poles inserted through
the front board, and screwed onto the bolts mounted in the back baffle.
Finally, the mirror box is glued up and clamped with the poles inserted,
to make sure they will go back in after the glue sets. The holes are
drilled for close clearance, so that there is no slop in the truss. Actually,
the poles are flexed slightly inward when the secondary cage is attached.
The second photo show the mirror cell, made of mainly 3/4" baltic birch
plywood, with an aluminum pivot bar. Flotation is 4-point. Contact
points are on Teflon pads on the wood, and PVC blocks on the aluminum pivot
bar. The bottom brackets which support the bottom side of the primary
mirror are brackets for curtains!
Finally, here's a photo of the mirror cell after stain, polyurethane, and
painting.
