The Rocker Box, Lid, and Ground Board
Returning to this photo to discuss the Rocker Box and
Lid...
I used 3/4" plywood for the bottom of the Rocker Box, the only place
in this design I deviated from using 1/2" ply. I guess my reasoning was that I
wanted the bottom to be extra secure, with airline baggage handlers, and all
Once I had the UTA and Mirror Box built (and nested together), I knew all
the dimensions the Rocker Box had to be, as well as how tall to make the Lid to
enclose everything. In fact, |
|
| the Rocker Box and Lid were separate pieces of one (unassembled)
box until I sawed the pieces in half (following carefully drawn lines, of course). I used
a Scroll Saw, though a Jig Saw would have worked, too. The four "keys," as I
call them (indented cutouts), are there so the Lid will fit securely left to right--the
profile of the bearing surface cutouts provide the same function fore and aft. By the way,
the Teflon pads must be cut into parallelogram shapes with two of the sides vertical, if
one expects to lift the Lid straight up!
Everything fit snugly; I even drilled three
holes in the bottom of the Rocker to accommodate the collimation bolts; and I had to drill
a hole in the Mirror Box to mate the Pivot Bolt into the Mirror Box when nested. The
Mirror Box rests, therefore, on the two Floor Levelers which keep the Tailgate closed and
two pieces of cork in opposite corners (you can see one of each in the photo).
Here you see the underside of the Ground Board. Note the ubiquitous floor levelers;
here used |
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as feet for the triangular Ground Board, or when unscrewed (and one
added), as feet for the four corners of the Rocker Box--this is how it travels on
airlines.
The Pivot Bolt, by the way, is simply a 1/2" carriage bolt with a lock
nut on the other side. I did, however, inset a couple of sealed router bearings into
the Ground Board and Rocker Box. These bearings had 1/2" holes in them and were
1-1/8" round, hence the Pivot Bolt's hole will not wear out so fast--an annoying
"slop" in many well-used Dobs. |
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