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The most captivating parts of a Rolling Ball Sculpture would have to be the track elements. The track elements are
various devices and mechanisms that interact with the ball. Track elements can be complex machined devices with levers and
switches, or simple inversions such as loop-the-loops or corkscrews. These devices come in two categories: the pure rail
elements, and the machined elements.
Pure Rail Elements
One of the more popular track elements is the inversion. Inversions can come in the form of loop-the-loops, barrel rolls,
corkscrews, or step-downs. Basically, any time the ball is riding on track above itself, the ball is in an inversion. The photo
to the right shows a barrel roll followed by a nicely banked run-out. Though I can create inversions of all kinds, they usually
appear in larger sculptures because of the speed required to carry the ball through.
This photo shows another inversion of a more complex design. You can follow the track from the top of the photo,
through the center of the inversion, into a sharp left-bank turn, through the inversion, and out to the left of the photo.
It is really an impressive section of bent track and it works very well.
This photo shows a fun track element I call a conical coil. The ball enters at the top and starts winding around the inside
of the coil. As the ball turns down the coil, it picks up more and more speed until it is ejected out of the bottom at a high speed.
In this case, the ball is ejected and immediately enters another conical coil about a foot away. At this point, it is really
moving!
Here is a nice track element that often tricks people into thinking the sculpture has a problem.
I simply call this balls-on-track because, well,
that's basically what it is. In this track element, the stationary balls sit there clearly in the way of the one moving towards it.
Most people think they are stuck there and the ball coming towards it will get stuck there too. However, because of
Newton's laws, the ball strikes the first ball and immediately ejects the last ball as if it passed right through. Actually, it is
the energy that passes through, carried off by the last ball. Everyone loves this one.
Machined Elements
Splitting a ball track into multiple paths is the best method for having a large number of track elements. In the
Mechanical Engineering Demonstrator, 12 different ball paths were required to convey the desired message. To supply 12
different ball paths with three lifting devices, track switching gates were required.
The simplest track switching
device is the Flip Gate. The photo to the right shows a marble entering the Flip Gate. When the marble passes through
the gate, it flips the switch to allow the next ball to go down the other path. These can be made in a vertical or
horizontal orientation. These gates are the simplest to make and can be stacked to supply multiple paths.
This photo shows the Circle Gate. The circle gate is a clever way to divide one ball path into multiple paths. As the
circle gate rotates, balls enter at the top left of the device. The rotating gate accepts the marble into a random slot
depending on the timing of the balls arrival. The slots varying depth dictates which of the four paths the ball will
continue on. The rotation of this device is created through a drivetrain from the motor of the lifting device.
The Plinko Gate is another device used to split a path into multiple destinations. The Plinko Gate was inspired by the
popular game on The Price Is Right called Plinko. The Plinko Gate accepts marbles at the top and randomly places the
marble onto one of five paths. The random characteristics are achieved through the disruptive nature of the pegs
as well as the oscillating entry ramp at the top.
Here is a very clever track element designed to convey Newton's laws. I call it Newton's Switch. This device uses a variation of Newton's Cradle to
switch the direction of the balls path. Using the photo for orientation, the marble enters from the bottom right at a
constant speed. The marble collides with the stationary hanging marbles at the end of the track. Energy passes
through the marbles, only for the end one to swing out and back into the hanging marbles. The Energy is then passed back
into the original marble which is sent on its way down a different path.
This photo shows a collection device designed to converge multiple tracks back into one path. Anytime a multiple path
gate is used, a collection device must also be incorporated. This device, called the Wave Collector, converges the balls
into one path for the Screw Lift.
Another clever way to converge marbles is through the use of a Spiral Collector. The Spiral Collector uses a pre-formed
shape to allow the marbles to rotate freely as they are spun in from converging paths. The marbles spin around
and orient themselves into a single path as they leave at the bottom.
This is only a small sampling of the devices available to add to a Rolling Ball Sculpture. I am continually developing
new ideas to perform practical or whimsical functions. When any new sculpture is on the drawing board, the
tastes of the person, and the feel of the environment help to dictate which elements to use. The track elements of a
successful Rolling Ball Sculpture will add intrigue and amazement to the already impressive display of creative engineering.
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