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The "Deep Space Scope"
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DS-3 | Rocker box construction
Ground board and bottom of rocker box, and top of rocker box, and
rocker box after the addition of stiffening plates.
We will build the ground board and rocker box from the bottom up.
- Create the base of the rocker
box. This is a square piece of plywood 15 1/2" X 17 1/2".
Mark a center point on this board. Drill a 1/4" size hole in the
center for a nylon screw. Using a drill, cut a 3/4" diameter
countersinking hole about 1/3rd of the way through this board.
Cover the bottom of this board with Formica, glued on with rubber
- Create the ground board. Create
a triangle 7 3/4" from the tip to the center, and about 11" on a
side. Drill a 1/4" diameter hole in the center for a nylon
screw. Create a countersunk hole here just like you did on the
rocker base above. This forms the TOP of the ground
board. Cut out three 1" diameter plywood rings, and glue and screw them
edges of the triangle. Trim the triangle to match the contour of
the 1" diameter rings. Place a 1/4" diameter, 1 1/2" length nylon
screw through the ground board, and place a nut on it. This locks
it into place. Then, on the opposite sides of the 1" diameter wood
rings, place three 1" magic sliders at the outside corners of the
baseboard triangle. These are the plastic things that people put
on the bottom of chairs so that they do not scratch the floor.
- Cut two 4" X 15 1/2" boards.
We will glue these to the top of the baseboard in a moment.
- Find the radius from the bearing
center to the edge of the mirror box. Measure from the center of
gravity (the centerline of the telescope at the location of the tape
above) to the BACK BOTTOM EDGE of the mirror box. This will be
the part of the telescope that is on the bottom and the furthest from
the center of the bearings and must clear the center bolt of the rocker
box. This will also represent the height of the center of gravity
above the center bolt of the rocker box, after we add in a fudge factor.
- Assemble the base board and rocker box
to this point. The height of the bottom of the curve that we need
to place in the side boards of the rocker box is calculated as
follows: Take the radius calculated in the last bullet. Add
in the height of the center nylon bolt. Cut this bolt off to make it as
shallow as reasonably possible. Add in a fudge factor of 1/2" to 1". We
need this fudge factor if we were off when we calculated the center of
gravity. Next, subtract the thickness of the Teflon
bearings (about 1/4"). Subtract the radius of the bearings created
above. Mark this height on the side pieces. Then, draw an
arc on these side pieces using the radius of the main bearings, plus
the thickness of the Teflon bearings. This is how we want to cut
- Cut this arc.
- Drill counter sink holes into the
Teflon, and attach them with 4 screws. On my scope, the Teflon centers
are 4 1/8" from the center of the rocker box. Generally, the
apart these bearings are, the more stable the scope. You will
also be adding more force onto the Teflon, thus increasing friction
(generally, a good thing). The further apart the bearings, the
higher the rocker box. This is irrelevant, until it gets taller
than the primary mirror box when collapsed for travel.
- Now, mark from the edge of the Teflon
bearings to the lower corner of the edge. Cut off this waste
- Glue the rocker box sides onto the rocker
- Cut two stiffening plates, 5 1/4" X 16 1/2". Glue
the bottom of the rocker box. Trim with the sander.
- Cut 4 small sticks, 1" wide X 3" inches long. Bevel the top
these sticks with the sander. Cover these with the fuzz from
strip of Velcro. Screw these to the sides of the
rocker box to hold
the bearings into place. (Notice that I only used two in the center
picture above. This was changed to 4, over the Teflon bearings, in the