The Mount
Making a 4.25 Inch Dobsonian
Reflector Telescope
The mount consists of three separate
parts, the rocker box, the fork and the base.
The
Rocker Box
The rocker box is just that, a box
that rocks back and forth. The box has
two wooden circles screwed to the sides.
These circles were made with a router plus circle jig. The size of the box is just big enough for
the tube to slide through.
My own modification to the box is to
fit it with a screw with a large handle to tighten the tube. This allows quick and easy balancing of the
tube. The screw will make small marks
on the tube. If you don't like this,
it's possible to shield the tube with a thin piece of metal, which needs to be
held onto the inside of the box somehow.
This screw also allows the scope to be shrunk down when transporting it.
The
Fork
The fork consists of three boards
screwed into a round base. The two
side boards have V shaped cuts for the rocker board circles to fit into. These V shaped cuts have Teflon strips
glued to them to reduce friction. Finding glue that will bind to Teflon is a
bit of a tricky but it can be done.
The
Base
The base is a second circle of wood
that fits below the fork. These
pictures describe show the first version which did not work out. The problem was that the base was not large
enough, and the scope tended to tip over.
I replaced the base with a large circle which solved this problem.
The
base has three short legs. These have
two functions. They provide stability
on uneven ground, and they are needed to allow the central bolt to clear the
ground. The bottom of the fork has
three furniture Tephlon pads screwed into it.
Between
these unseen pads and the base is an old 331/3 vinyl LP record. The three circles, the fork, the record and
the base are held together with a very large locking bolt.