Theatre Design & Technology - Dec 1965 - 12

System #2 A second system was designed and built
in the University Theatre shop employing a modular
steel channel system, Unistrut, based on a 1-5/8"
channel cross-section. Other simi lar systems, like
Mult-A-Frame and Kindorf offered a variety af fittings at a somewhat lower price, but were judged of
a slightly lower manufactured quality.6 All of the
systems named have in common the basic joining
device which is in effect an oblong nut shaped so
that it is retained at any point inside the channel by
a steel spring until tightened in place with a standard machine bolt or cop screw. These systems are
particularly suited to stage uses because they are
designed for demountabi lity and rapid, accurate
assembly by unskilled technicians.
As in the earlier system, the channel leg adjustment
is central to this solution: a back-to-back channel
section allows the most flexibility, with two hex
head cap screws making the joint (Figure 2). A
separate leg is necessary for each 12 inches of leg
height, and adjustments are possible on 1 Y2 inch
centers. Diagonal bracing proves to be a key problem: with no slot or slip feature; two sets of braces
are necessary to bring the platforms to a maximum
of sixty inches of height. While the necessary three
sets of legs may appear to represent an extravagance,
these stock lengths prove involuable for additional
mounting, joining and suspending tasks: one additional result was an even deeper commitment to the
channel system through purchase of additional stock
ten and twenty foot lengths.

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SYSTEM NUMBER TWO

(modular channel system)

SYSTEM NUMBER THREE (modular channel system;demountoble
plywood top, ioined to chonnel with o"Z-shoped" fitting)

The units are disassembled at strike down to the
four channel spanners which are bolted directly to
a five-ply top. This assembly weighs about 60 lbs.
An open -end wrench is neededuactua Ily two are
necessary to break the leg lap joint, and a dozen
speed the job measurably at strike. One-half-inch
hardened and plated bolts and nuts, whi Ie unnecessary structurally, are impossible to strip, easy to
finger-tighten, and a little more difficult to lose than
smaller sizes. The two-inch flat washer is necessary
for bridging the channel opening, since smaller
stock washers of less thickness tend to collapse
and force aport the channel walls. Facing is supported by 1" x 3" stock bolted to on "L" fitting
which bolts in turn to the spanner or a leg. The
same "L" fitting is the basis for joints between
platforms, uti lizing leg lengths of the basic channel
section. Smaller platforms are possible without
adding any components except the padded top, since
a suitable leg section may be used as the spanner.
In practice, smaller sections are often filled in between stock units by simply bridging between spanners of exi sting platforms, or canti levering beyond
them, inserting a modular leg whenever necessary.

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While the system will appear overdesigned structura Ily, it is actua Ily intended to approxi mate the
established ideal with regard to depreciation. The
accidental damage which can be inflicted backstage
with a twelve foot length of two-by-four lumber by a
careless carpenter, is not difficult to imagine. The

IOSITT

THtATRE DESIGN AND TECHNOlOOY

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