following is a description of how I made my Radar Section. While
it mat not be the BEST way to do it, it should at least provide
a good starting point.
The Radar Section consists of two sections, the Upper Section &
the Lower Section. The upper section is, in basic terms, a stack
of 10 (ten) 1/8" thick circular pieces (5 each of 2 different
sizes stacked alternately) with 8 (eight) "fins" and a
Lower Section is made up of 2 (two) 1/8" thick circles mounted
on the top & bottom of a center ring that is 1-1/4" thick.
See illustration below.
can be constructed from wood, acrylic (plexiglass) or a combination
of both. I made mine using both wood & acrylic.
4' x 4' sheet of 1/8" thick acrylic plexiglass)
2' x 4'sheet of 1/2"plywood (**actual measured thickness
5/8" Plastic is also OK)
small sheet of 1/4"thick plastic (or wood) for "fins"
of 1-1/2" diameter PVC pipe (for bubble support)
1-1/2" diameter PVC pipe end caps (one for top & bottom
of pipe to support bubble)
tube of Plumbers GOOP adhesive
can of Fiberglass Resin & Hardener (to coat wood for finishing,
hole saw attachment (for drilling out center holes of upper circles)
the Upper Radar Section
For the 10 circles, I used 1/8" thick acrylic (I used clear,
but color is not important since it will be primed & painted
later) and cut 5 circles with a diameter of 6-7/8" and 5 with
a diameter of 7-1/8". Each circle will also have a 2-1/4"
center hole cut out. Before you cut out the center circles, you
should mark one of the larger sized ones (this will be the top one
when assembled) for the placement of the 8 fins. Mark directly across
the center then bisect this line across at a 90-degree angle. Now
mark the 2 remaining lines exactly between the two lines that you
just marked, giving you a "pizza-type" pattern to show
the positions for your 8 fins.
center holes are for the PVC end cap to slip through & mount
to the lower section. You will insert a 1-1/2" PVC pipe into
the end cap support the bubble. Since there is very little margin
for error & circles are very difficult to cut, you may want
to pay a couple of extra bucks to the plastics company to cut these
for you. If you do this, make sure they mark the "dead center"
of each so you can cut out the 2-1/4" center holes (unless
they do that for you as well.)
out the center holes in each is fairly simple to do with a hole
saw that attaches to your drill. You can buy these at any hardware
store in a kit for that come with several different diameter blades.
Make sure you buy your 1-1/2" PVC & PVC end cap first before
cutting out the center holes! The actual size of the end cap can
vary depending upon the manufacturer and you want to make sure it
fits in the opening. You can make the hole larger if needed to accommodate
the end cap, as the size of this is not crucial. Just make sure
the center hole is large enough for the cap to fit inside easily.
that you have the 10 circles, make sure the cut edges are smooth,
remove the paper backing (if you used acrylic), then stack &
glue them alternately, starting with a smaller circle at the bottom,
then a large circle, then small, etc. until they are all glued together.
**Save the one that you marked the fin placements on for the last
one (leave the paper on the top of this if it is marked). Use a
small amount of Plumbers GOOP to glue them together. The center
holes are useful in making sure they are properly aligned. Make
sure you don't get any GOOP too close to the edges! You don't want
it to seep out when you press them together! Clamping the rings
together isn't necessary, just press them firmly together, making
sure they stay in alignment.
is a template included in this guide for the fins, but the measurements
are easy enough to duplicate to make your own. You will need 8 fins
made from 1/4" material. Again, I used acrylic, but any material
will do. If you used wood for these, it's a good idea to coat them
with fiberglass resin and finish-sand them before attaching them
to the ring section. You don't want any wood grain to show! This
applies to all parts that you make! Sanding them is usually much
easier before they are assembled.
cut out the basic outline, and then cut out the 5 notches as shown
in the diagram to the right. Mark a vertical line at a 1/8"
depth then mark out the cut-outs for the notches. These are tricky
little cuts, so take your time.
a 1/8" thick grinding wheel that I attached to my drill (set
the drill on a very slow speed). I clamped the piece to my workbench
and carefully cut them out. The hardest one was the one at the top
because of it being near the top edge that over hangs, but it was
still fairly easy.
alternate method for this would be to cut out 1/4" wide notches
in the ring section and slide the fins (with no notches in them)
into the notches in the rings. The outcome is basically the
same & may prove to be easier to do.
you have all 8 pieces cut out (make sure there is no wood grain
showing if you used wood), put them aside until you complete the
lower section of the Radar. The final piece is the center ring that
goes in the middle between the fins. It is 4-1/2" in diameter,
3/8" tall and approximately 1/8" thick. Many people have
used large, plastic cups and cut this ring from that. I made mine
out of a solid piece of 3/8" thick wood and cut out a center
hole for the PVC only. Once the bubble lifter is in place, you have
to be pretty tall and really looking to see that it isn't a ring
but actually a disk. I just glued it in place with GOOP and it worked
the Lower Radar Section
Cut 2 rings out of the 1/8" thick material to a diameter of
12-5/8". Again, have your plastics store cut these for you
if you don't feel you can cut them accurately. The circle that will
go on the bottom needs to have the center cut out to leave only
a 1" wide ring to allow you to access the inside of the Radar
Section for motorizing. Even if you don't plan to motorize right
now, do it anyway in case you change you mind later! The top circle
only needs a hole that is large enough in the center to allow for
a drive axle (for the crown spinner) and a smaller hole to the side
of it for wiring. I made my center hole 3/4" in diameter and
the hole for the wiring about 1/2" in diameter.
The Center Circle shown in the bottom of the diagram to the right
is made from 2 (two) pieces of 5/8" thick material laminated
together to make up a total of 1-1/4" thick.
the 1/2" plywood for this (it actually measured 5/8" thick,
so measure yours before you buy!). I glued 2 pieces together using
wood glue and clamped them together to set overnight. You may be
able to find wood or other material that is 1-1/4" thick, so
out the outside first (12-3/8" diameter) very carefully using
a jigsaw. If the saw tried to waver off course, I let it only go
to the outside of my line so I could sand it down to the right shape
when I was done. Then I cut out the inside to leave a 1" wide
ring. The width of the ring isn't critical & it doesn't have
to be a perfect circle on the inside cut, just make sure it's wide
enough to give proper support. If you use wood for this, brush on
some fiberglass resin on the outer edge and sand it smooth.
the 3 pieces together using GOOP and let dry. Again, clamping isn't
It All Together
Glue the Upper Section to the Lower Section using GOOP, making sure
that the Upper section has the smaller sized ring on the bottom.
Once that is set (it should be securely in place in about an hour),
glue the eight fins in place. Use an Exacto knife or razor blade
to mark the plastic at the point where the fins will attach &
remove the paper backing (if you used acrylic).
a small dab of GOOP on the very bottom of the each fin and another
at the top part that rests on top of the stack of rings only. This
will hold them more than securely enough once the GOOP sets.
that's left is to install the bottom PVC end cap in the center.
You need to drill out holes in it to match the holes in the top
ring of the Lower Radar Section for the drive shaft & wiring.
It can then be mounted in place. I drilled out 3 small holes and
used small nuts & bolts to secure it in addition to GOOP. The
GOOP itself is probably strong enough to hold it securely, but since
this is what will support the bubble and brain assembly, why take
chances! Now it only needs to be primed & painted! Make sure
you don't get any primer into the PVC end cap as these are generally
tight fitting and you may need to remove the PVC pipe at some point!
I sanded the ends of the PVC pipe so they slid in & out more