Theatre Design & Technology - Summer 1999 - 60

tech EXPO
1999
In theatres with walkable grids but no pin rail for running spot lines, stagehands often resort to deadhanging lightweight loads, like masking, by tying them directly to the grid channels. In a typical deadhang situation, a stagehand lowers the end of a rope from the grid to the stage floor where it is tied off to
the object to be flown. The stagehand then hauls the object into the air until it is at trim and then ties the
rope off with a clove hitch to the channels forming the grid. Often a piece of carpet or other padding is
wrapped around the grid channels to keep their sharp corners from cutting the rope.
It is difficult to tie a clove hitch willie supporting weight on the rope and more difficult still when attempting to do so around a piece of carpet wrapped around the channel. Furthermore, the higher the object is flown the more excess rope ends up on the grid. Either the excess rope must be pulled through the
hitch or the hitch must be tied with the rope doubled up. In either case, maintaining the desired trim
while tying the hitch or adjusting the trim after the hitch is tied is frustrating.
The "gridbit" solves these problems. The gridbit is simply a board with a hole in the center, flanked
by a pair of birch dowels. (See figure 1.) The dowels penetrate through the bottom of the board and into
the spaces between the grid channels, so that by rotating the board slightly the dowels will automatically
center the hole over an opening in the grid. The stagehand passes the rope through the hole to the stage
floor, as before, but, after hauling the object to trim, merely throws a series of figure-eights around the
dowels projecting above tlle board to tie the rope off. (See figure 2.) Ttim adjustment is just as easy: simply remove a few of the wraps around the dowels and let the rope slip to the new trim, then add the wraps
again to secure tlle load.
Construction of the gridbit is simple as well. Glue a rectangle of JA" ACX plywood, approximately 6"
x 15" to a 10" x 15" rectangle of 2" ACX plywood. The projecting portion of the W' plywood provides a
footrest to keep the gIidbit from moving while hauling up the rope and the extra thickness helps to secure the dowels. The actual dimensions of the gridbit base are not critical and may be adjusted to meet
the specifications of each particular
grid. Drill a 2-inch hole in tlle center of
the smaller rectangle and round over the
edges of the hole with a router to protect
the rope. Drill the holes for the dowels at
a distance from the center of the rope
hole equal to the distance to the (enters
of the adjacent glid openings. Insert two
7-inch long dowels through the holes
and glue in place so that JA" projects
through the bottom of the board and 5
inches projects from the top.
Gridbits have been tested without
movement or failure to a static load of
over tllree hundred pounds, but should
be limited only to loads a stagehand can
lift. For quick installations where a pin
rail and spot line blocks are not provided, gridbits offer an inexpensive and
simple solution. *:.

s u '" '"

E R

9 9 9

TZ>&T

Table of Contents for the Digital Edition of Theatre Design & Technology - Summer 1999