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,

mbox2g.gif (66696 bytes)

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

gbdg.gif (77672 bytes) 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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