I elected to build the brain out of aluminum. The
triangular upper and lower sections are 1/16" sheet aluminum, and the side
panels are a thinner aluminum which started out as a kick panel for a door.
The outsides were cut with a scroll saw.
To cut the shapes, I first scanned the patterns from Dave Painter's plans,
then printed them on full size laser label media and stuck them to the
aluminum sheet. I used a drill press to cut 1/16" holes inside the shapes,
then used a Dremel tool with a small ball cutter to connect the holes, and
finished off the shapes with a set of needle files. The eye holes were
enlarged slightly to accomodate Mark Thompson's eye lenses.
||Top Plate Ledge
To keep the wraparound panel properly secured and shaped
during assembly, I cut a duplicate of the bottom plate shape out of 3/4" pine and used
plastic push pins through the cutout holes to fasten the wraparound to the wood
form. I also used the wood form to bend the wraparound panel. The 5
rectangular objects on top of the wood form are some scrap 1/4" acrylic, to raise
the bottom plate high enough so the adhesive would not stick to the wood. I used
J-B Weld to glue the bottom plate to the wraparound panel. The join was
not perfect, but I was able to pack in enough J-B to fill the gaps. I used a
long aluminum bar clamp to hold the bottom together. Note - before you apply
the J-B Weld, be sure to roughen the edges of the join with coarse sandpaper or
a file, or else it won't stick well.
The open ledge to support the top plate was attached in the
same way as the bottom plate, with the wraparound pinned to the wooden form.
Then, the wooden form was removed and the front panel attached with more J-B
Weld. The eyepieces and two smaller filler pieces were then attached, more
J-B Weld was slapped on to fill the cracks and a couple of scratches, and I
did some preliminary sanding. The top plate fits snugly into the top of the
|Brain Cup Parts
I found a tapered aluminum cup that appears to be some sort of
weird looking salt shaker, but has almost the perfect dimensions to be used for
the brain cup. I cut a 4-1/2" aluminum ring to form the bottom part of the cup,
and a 3-3/16" disc (slightly larger than the 3" disc called for on the plans)
for the top. Also in the picture is the 12V, 7RPM Hankscraft
motor I got from Mike Joyce, to turn the crown and move the light rods. The
second picture shows the cup after I flattened out the top of the cup and
attached the top plate and bottom ring with J-B Weld. I filled in the seams
with more J-B Weld and did some preliminary sanding. And finally, why do
anything simple when you can do it the hard way? I wanted to cut several
sections of nested brass tubing, hence the odd looking Dremel rig.
||Drill Press Setup|
I decided to make my light rods out of brass tubes. At
first, I experimented with 1/2" aluminum rod, but after failing to drill out a
centered hole and discovering I had nothing which would turn down the ends, I
gave it up as a bad deal. I picked up a set of 12" nesting brass tubes from
K&S at the local hobby shop, in sizes of 7/16", 13/32", 3/8", 11/32", 5/16"
and 9/32", and 2 sections of 1/4" tube. According to Craig Reinbrecht's
measurements, I cut the 7/16" tube in 11/16" lengths, nested the 13/32"
and 3/8" tubes and cut them in 1/8" lengths, and nested the 11/32", 5/16"
and 9/32" tubes and cut them in 3/8" lengths. Finally, the 1/4" tubes were
cut in 3-15/16" lengths. The nested tubes were then soldered with a mini
butane torch and silver-bearing paste ("Solder Weld" from Radio Shack). The
net result looks a lot like Craig's diagram.
In order to attach the pushrods to the light rods, I drilled a
1/8" oblong hole through the top of the light rod near the end for the 1/8"
brass pushrod. Then I used a tiny 1/32" bit to drill a hole through the side
of the tube and the bottom of the pushrod, for a piece of piano wire as a
hinge. The right hand picture shows my drill
press setup for the 1/32" hole. Buy 2 of these drill bits - you'll break
|Cup and Light Rods
||Inside the Cup
The sockets for the light rods are from Radio Shack, with
a Dremel tool and cutting wheel used to remove the bracket. A length of 22 gauge
stranded hookup wire was soldered to the center post of the socket, then the
socket was soldered to the end of the light rod with solder paste and the
mini torch. The wire is led out through a small hole in the light rod right
after it enters the cup with a short length of spaghetti tube to keep it away
from the edges, and a ground wire is soldered to the outside of the
tube right next to it. I painted the light rods and brain cup with
self etching primer and
Duplicolor Cast Coat Engine Enamel CT302, then attached the pushrods to the
light rods with a piece of 1/32" piano wire, bent over to keep it in place.
The rest of the brain was also painted with Cast Coat, along with 3 short
(3/8") pieces of 7/16" brass tube to cover the topside light sockets. I
didn't like the looks of the bare sockets sticking up. The brain cup is
attached to the rest of the brain with four 6-32 machine screws threaded into
holes tapped in the top of the cup.
||Neck Pipe Attached
||Inside the Bubble|
The neck support is a length of 1-1/2 (ID) PVC conduit, with
the flared end at the top to hold the Hankscraft motor. I glued a couple of
flat PVC round pieces to the top of the pipe to provide a flange to screw to
the ring on the underside of the bubble plate (1/4" curved version from
Planet Plastics). Four 6/32 screws attach the
lower ring to the top of the neck pipe, through the bubble plate. In between
the ring and bubble plate, I inserted a 1/8" foam ring (Trackbed, at your
local hobby shop) as a spacer. Another foam ring sits underneath the brain
cup on the upper side. Four more 6/32x3/4" screws attach the brain cup
to the lower ring, through holes tapped in the brain cup. Finally, I drilled
four holes on the perimeter of the bubble plate, 3/16" in from the edge, and
countersunk them. I carefully tapped holes in the bubble itself for 6/32x1/2"
nylon screws, and screwed the bubble plate to the bubble. The white nylon
screws aren't too obtrusive, although I would have preferred to use clear
acrylic screws (couldn't find any around here).
|View from the Top
The eye lenses are from Mark Thompson, and are just press
fit in place, for now.
The vanes for the crown were cut from .032" aluminum with
a scrollsaw, then sanded down to size with the disc sander. The 4" circular
plate was cut from 1/16" aluminum with a circle cutter on the drill press.
The holes were drilled, then I did a first pass with the polisher on the
circular plate. The vanes were then bent to a 45 degree angle in a vise,
and pop-riveted to the plate. I'll polish the vanes and attach a collar to
fasten the crown to a 1/4" shaft.