Build Your Own Combat Robot

280 Build Your Own Combat Robot
FIGURE 13-1
Sumo ring
dimensions (units
are centimeters)
The Sumo Ring Specification
The sumo ring is basically a large, smooth, flat disk made from solid black vinyl.
Obtaining a 154cm-diameter piece of vinyl is often very difficult, so most
sumo rings are made out of regular plywood. Figure 13-1 shows a drawing of
the sumo ring. Note that all of the dimensions for the mini sumo ring are exactly
half of the dimensions of the international sumo ring.
The sumo ring can be made out of virtually anything as long as the overall dimensions
are maintained. Most sumo rings are made out of plywood. For a mini
sumo ring, a 1-inch-thick piece of plywood will work. When building an international
class sumo ring, it can be difficult to find a single piece of plywood that is
154cm wide. The easiest way to solve this problem is to make a set of four semicircles
that have a 154cm radius. They should be glued together so that the seams between
the two semicircles are at 90 degrees from each other. To make the sumo
ring meet the 5cm height, a set of strips can be glued to the bottom of the sumo ring
to form a spoked wagon-wheel pattern. The sumo ring can be made solid, but that
will result in a very heavy sumo ring. For the large sumo ring, it is recommended to
use screws in addition to the wood glue.
After the sumo ring has been assembled, the top surface needs to be sanded flat,
and any depressions need to be filled in. Paint the finished top surface with a
semigloss or flat black paint. Paint the outer ring gloss white, and the two starting
lines brown. The side of the sumo ring can be any color, but white is usually the
color of choice. The black-and-white color scheme for the ring’s surface and borders