Theatre Design & Technology - Feb 1973 - 12

NO WINGS?!
NO FLIES?!
DAVID Y. JAGER, Illinois State University
In most college production programs there is a desire
to use a turntable for scene shifting purposes. This desire
is particularly acute in theatres where there is little or no
wing (see Westhoff Theatre plan) or fly space. Such a
problem faced us.
I wanted a turntable that was, first of all, relatively
inexpensive ($900 - $1,000). It had to be a permanent
piece of equipment that cou Id be used at any time without
permanently mounting it on the stage. When not in use,
the complete unit had to be stored compactly. The turntable was to be used for the summer season and
necessitated an overall height of 18 inches. Thus not only
did we have to design the turntable for the summer season, but in order to make it possible to use at other
heights at other times, some sort of leg device would be
needed.
TRUSS CONSTRUCTION: Taking these criteria into
consideration, I decided to use 16 trusses (figures 1 & 2).
Since wood construction defeated the variable height
criteria, I decided on slotted steel angle for the structure.
Everything on the trusses remains intact for storage except
the verticals, which are cut to length as required. The end
vertical is placed closer to the center of the turntable to
allow for the drive track (figure 3). A 4 inch diameter steel
wheel caster is bolted in place near one end of each truss.
The casters ride on a ring 6 inches in width made of laminated 1/4 inch tempered masonite and 16gauge galvanized
sheet metal, which is screwed to the stage floor (figure 4).
The other end of the truss is bolted to a 1/4 inch steel
plate -(figure 5) that rests on a thrust bearing plate also
attached to the stage floor (figure 6).
Four of the trusses are joined at the center over the
thrust bearing for basic stability (figure 7). The other
twelve are not attached at the center except to the plate.
A piece of 1" x 4" is attached to the top of all the trusses
for securing the plywood tops (figure f,'.
Additional slotted angle is used to tie the bottom of the
trusses together in such a manner to provide a place to

mount the casters (figure 3). The slotted angle is also used
to support the perimeter of the plywood tops and to tie
the tops of the trusses together (figure 8).
TOP: Three-quarter inch plywood is used for the top.
It is covered with 1/2 inch homasote and canvas to provide a sound absorbing, long-wearing surface.
DRIVE TRACK: A 6 inch wide ring of 3/4 inch plywood with a 1/4 inch reinforced plywood facing 3 inches
wide is bolted around the circumference for the drive
wheels to push against (figure 8). The facing is coated with
safety tread paint for traction.
DRIVE UNIT: A 3/4 horsepower, 110 volt gearmotor
is used to power the turntable. It is provided with a speed
controller (0-35 rpm at 826 inch/pounds of constant
torque), a forward/reverse switch and a dynamic brake
(figure 9). I found the gearmotor to be a most efficient
unit, in fact more than I needed in terms of the torque
rating. The gearmotor is bolted to a separate frame that
simply rests on the floor. The tension on the drive chain is
taken up by a sleeve with a bolt and nut work ing against
it. The sleeve is crossbraced and welded to the wheel
plate (figure 9).
DRIVE WHEELS: Power is transferred via a #50 roller
chain to two motorcycle rear wheels. An additional ball
bearing idler sprocket provides a greater purchase to the
wheel sprockets (figure 10). The shafts for the wheels are
welded to a 1/4 inch steel plate reinforced around the
edges with 3/4 inch square steel tubing. These wheels
come with rubber shock absorbing devices wh ich I feel
are a definite asset for smooth starts. The wheels just rest
in these devices making it possible to remove them for
maintenance and storage.
A plate with a hook is attached to the stage floor at
each end of the wheel plate. These hook plates are the
only other parts that have to be attached to the stage
floor besides the center thrust bearing plate and the
caster track. A turnbuckle connected from the hooks to
the back of the wheel plate can be tightened to exert

THEATRE DESIGN AND TECHNOLOGY

FEBRUARY. 1973

Table of Contents for the Digital Edition of Theatre Design & Technology - Feb 1973