A Bubble Screen
Exhibit
The
way I built the ones I built:
You need a trough.
A
small one could use
the plastic or metal trays for paint rollers or for hanging wallpaper.
A
wooden box lined
with fiberglass can be long and straight, curved, or angled like a
mirror in a
clothing store.
I once cut a tractor tire in half zigzagging around the center
of the tread between the lugs. (Dozens of saber-saw blades later . . . ) It is still in service after some 20 years.
No fish-line
required.
Place
screw eyes in the
trough to hold the bottoms of the fish-line. Put some epoxy or silicone
sealant
in the holes so you don’t create leaks. If the trough is light, you
have to
hold it down or the fish-lines will lift it. If it is on the floor,
anticipate
kids tripping over it.
You need a bar.
I
like PVC pipe, an
inch or so in diameter, with end caps to fit. If you make a three-sided
screen,
there are 135-degree elbows available. For a circular bubble, I bent ¾”
gray
electrical conduit using boiling water to soften it. (I made a long
boiler with
a piece of galvanized pipe and a hot water heating element.) PVC pipe
is light
enough that it will not seriously injure a child if it drops on him.
Drill
small but not
snug holes through the ends of the pipe at the distance of your
fish-lines. To make it ride straight on
the fish-lines,
you can either triangulate the lifting rope or put a Tee and an
extension in
the center. Curved or angled bars will need three or more points of
support.
You need fish-line.
Use
heavy weed-eater
cord. Fisherman’s knots hold well, but put a bumper (rubber hose or
similar)
over the knot or the bar will wear it out quickly. The bar will ride up
and
down the fish-lines, which form the edges of the bubble. Keep the line
handy
for repairs. You do not need fish-line for a circular bubble ring.
You need a support.
This
will hold the
tops of the lines and a pulley for the lifting rope. Anticipate that
sometime
soon, a heavyset twelve year old will attempt to shinny up the rope.
Attach it
to the ceiling, to a tripod, to a support from the floor, but attach it
well.
Screw eyes again will hold the fish lines (Thread them through the bar
first).
You need a pull rope.
I
like nylon. It is
soft and flexible and can be thrown in the washing machine when it
turns gray.
3/8 inch or so is nice; sear the ends over a flame. Tie knots in the
pull side
for soapy handholds and to keep it from running the wrong way through
the
pulley.
Gordon McDonough
