drill used for direct drive of the binochair, as detailed
on the previous pages 1 through 7, is operated at slow speeds
when slewing. Since the drill used is a variable speed drill,
just a slight pressure on the drill trigger will rotate the binochair.
One advantage of this is that there is almost no noise at these
slow drill speeds. A disadvantage is that the rotation control
is course; and fine adjustments are best made by not using the
drill but rather by rotating the binoculars slightly. Another
disadvantage is that there is horizontal pressure placed on the
vertical electric drill when slewing.
An alternative is to use a speed
reducer (gear reducer) between the drill and the small sprocket.
In shopping for gear reducers, I found that most are for industrial
applications and expensive, costing around $150. Lower priced
gear reducers are for hobbie projects and robotics and tend to
be to very light duty; not hefty enough for rotating the binochair.
After searching for gear reducers, I decided to use the gear reduction
afforded by an electric ice cream maker
we were no longer using. I found its gear reduction to be ideal
for controlling the rotation of the binochair. The gearing is
very robust since it was designed to mix ice cream as it hardens....if
you ever hand cranked a non-powered ice cream maker, you understand
the torque required.
I decided to install the gear
reducer so that I could easily return to the "drill only"
version if I wanted. I have found that I prefer the binochair
using the gear reducer. Operation of the binochair is noisier
than with the "drill only" method but not more offensive
than the noise made by a Meade LX 200 (that I also own). Slow
speeds of the drill provide a slow motion control for my 25 X
100 binoculars. Faster speeds of the drill allow slewing to new
sections of the sky. The gear reducer provides for smoother operation
of the binochair when slewing. My recommendation to anyone planning
to build a similar motorized chair is to use a gear reducer (ice
Parts for Speed
1. Remove the closet
door rollers previously installed in Step 12 of Page 3.
2. Drill a 5/8 inch hole next
to the existing hole (see photo). The location of the hole is
determined by measuring from the center pivot out to the center
of the drill arbor that was used for mounting the small sprocket.
For my binochair this location was 17.5 inches from the center
pivot. Be sure to get the hole's location as precise as possible
so that the chain is not too tight nor too loose when it is mounted.
3. This is the electric ice cream
maker motor/gear unit that I used. Electric ice cream makers are
readily available on ebay. I bought one on ebay for $10.50 to
have as a spare.
4. This is the ice cream maker
with plastic cover, wires and fan removed from the motor shaft.
The drill will use this motor shaft to drive the binochair:
5. The ice cream maker has a 8
pointed large gear that drives the ice cream bucket paddle. I
found that a 1/2 inch square head bolt fits into it perfectly.
The bolt with washers, small bicycle sprocket
and nuts are shown below:
6. Use a 1/2" X 5/8"
steel spacer as an insert through the chair base plywood. I cut
the spacer below to the same thickness of the plywood with a hacksaw:
7. Use a slow curing high strength
epoxy (I used JB Weld) to secure the spacer and washer to the
hole in the chair base plywood:
8. Drill holes in the plastic
arms of the ice cream maker to attach to chair base plywood with
3-inch wood screws. I just keep the ice cream maker attached to
the chair base and don't remove it. If you want it to be more
easily removable; use bolts and wingnuts.
9. Cut a hole in the plastic cover
a little larger than the diameter of the drill chuck:
10. Saw plastic cover in half
with a hack saw:
11. Screw one half of the plastic
cover onto the ice cream maker using two original screws. Use
a rubber band to hold the other plastic cover half in place .
This rubber-banded half can then be easily removed to tighten/loosen
the drill chuck.
12. I kept the original wood blocks
installed in Step on Page for holding the drill. Instead of replacing
them, I added two pieces of wood and
styrofoam to adapt the drill holder for the new hole position:
13. Cut two small pieces of 1/8
inch panel board (or other material) as shown and superglue rubber
grippy material where contact will be made with the drill battery:
14. Completed unit installed on
chair base - The drill is higher now and easier to reach:
I found that for transport, the
two wooden parts: chair base and groundboard, could be left attached
together. Their combined weight was still easy enough for me to
carry and lift into my van. To keep the chair base from rotating
on the ground board while carrying and during transport, I installed
three hand knob bolts through the
chair base plywood and into metal T-nuts
on the ground board. I keep the ice cream machine on the chair
base and only remove the drill during transport. When I arrive
at an observing site, my setup steps are as follows:
1. Lay down chair base/groundboard,
undo transport hand knobs and level.
2. Install drill in its holder
and tighten drill chuck onto ice cream machine shaft. (Front half
of ice cream machine cover is held on with rubber band)
3. Place chair on chair base and
install bungee cords.
4. Install binoculars on sliding
5. Relax and enjoy observing the
wonders of the night sky:
If you found these construction
details helpful in building your own binocular chair and would
like to let me know how it went for you; you can contact me at
the following email address:
Detailed procedure for drill-powered
astronomy binocular chair.
Binocular mount for Apogee 25X100 large
Comfortable observing with big astronomy
Reclining chair for large astronomy binoculars.
Ice Cream Maker - Gear Reducer used from
Ice Cream Maker