Theatre Design & Technology - Summer 1984 - 22

Stock
2 x4 Wood

Frame
Weight'

I I

341bs.

$20.66

53.0 Ibs.

$22.48

Frame Cost'
(Materials

Onl~')

Deck

Total
Weight'

Total Cost'
(Malerials Only)

¥.l CD

1061bs.

$39.21

15/16 "

V2 AC

951bs.

$42.33

3h"

3h AC

1161bs.

$50.08

9/16 "

V2 AC

101 Ib .

$44.86

9;'16 "

3h AC

1221bs.

$52.61

9;'16 "

V2 AC

77 Ibs.

$36.93

I Y,."

3h AC

981bs.

$44.68

'/,"

V2 AC

81 Ibs.

$39.30

1"/,."

3h AC

1021bs.

$47.05

V2 AC

861bs.

$41.68

15;;6 "

3h AC

1071bs.

$49.43

'i, "

V2 AC

821bs.

$39.41

I 'Is"

3h AC

1031bs.

$47.16

V2 AC

861bs.

$40.74

1J1t61/

¥.l AC

1071bs.

$49.49

s/,"

V2 AC

92 Ibs.

$44.28

13/16 "

3h AC

1131bs.

$52.03

s/,"

Flex

Steel
2 x 2 x 16g

B
E8

59.0Ibs.

$25.01

Steel
lx2x16g

0
ITO
CD

rn
§

34.7 Ibs.

39.4Ibs.

44.3 Ibs.

39.7Ibs.

44.4Ibs.

$17.08

$19.45

$21.83

$19.56

$21.89

there was not an opportunity to test thf
bolted legging system under the rigor!
of actual production. The odd shape~
of the CSF units meant that some wen
larger than 4 I X 8 I and some werf
smaller. Therefore, an exact compari·
son of strength and deflection is nOI
possible, although it can be assumec
that stock 4' x 8 I units would be a!
strong.
To summarize the results of thf
original study and the subsequenl
follow-up, I recommend constructin~
stock platforms as follows. The fram
ing of the stock units should be made 0:
I" x 2" by # 16 gauge steel tubing anc
the deck should be 314" AC plywood
The frame design should include a Ion
gitudinal support so that the plywood i:
supported on 24" centers. Legs am
casters can be mounted to a pre-drillec
\14 " steel plate in each corner. Lockinl
can be solved by using casket lock.
mounted in a logical arrangement to al
Iowa variety of configurations. Use 0
this system of platforming will sav,
much time and effort in that the plat
forms are quite durable, light, strong
inexpensive, quick to assemble, inter
lockable, and easily adapted to legginl
and castering. While there is alway
room for improvement and refinement
this system is certainly a solid beginning

NOTES
49.6Ibs.

$24.43

Clear fir @ 1.25Ibs/ft., 2x2x 16g @ l.71lbs/ft, I x2x 16g @ 1.26lbs/ft
Clear fir @ 75.8!! ft, 2x2x 16g @ 72.5!! ft, I x2x 16g @ 62.1!! ft
3. 3h CD @ 72 Ibs, V2 AC @ 42 Ibs, 31<1 AC @ 63 Ibs
4. 31<1 CD @ $18.55, V2 AC @ $19.85, 3h AC @ $27.60
I.

Based on standardized weights of 2.2 pound
per square fOOl for Jj," plywood, and 34 pound
per cubic fOOl for clear Douglas fir, the theoret'
cal weight of the frame and deck would have bee
109 pounds. However, there is often considerabl
\ eight difference from board to board, due i
pan to water content as well as type of wood.
I

According to Milot, there is no chan COlT
paring the relative strengths of wood and ste,
beams. It was necessary to consult trength spec
fications for each and then work the figures int
formulas to determine deOection and maximul
loading per square foot of surface area.

lent to approximately eighteen 4 I X 8 I
platforms). Early in the planning, I decided to employ the results of the yearlong study. The platforms consisted of
I" x 2" by # 16 gauge steel tubing frames
with longitudinal supports on 24" centers. Tops were cut from 314" AC ply\vood. Legs were made of I" x I" tubing and placed roughly in each corner
of the platforms, equating to four legs
on a stock 4 I x 8 I unit. These legs were
braced with \14" steel rod. Casket locks
were used as an interlocking device.
By the end of the season, I realized
that the design was an excellent one in
many respects. The frames were quite
rigid and strong with hardly any flexing. Extensive acrobatics were used in
the production but they failed to harm
20

the platforms. No warping was encountered during the full season even
though the units were stored outside
without cover. Weight was also reasonable. The platforms were shifted almost every day (Shrew ran in repertory
with two other productions that did not
use the full stage extension) with little
serious complaint from the stagehands.
The casket locks worked well but were
noticeably aged by the season's end.
The platforms worked so well that they
were stored for possible future use.
The major differences between the
research-developed platforms and the
ones used at CSF were the legging and
the general shapes. The CSF platforms
were rigged with permanent legs built
for the particular production. Thus,

Theatre Design & Technology / USITT /Summer 1984

3 For a more complete under tanding of dete

mination of plat form strength see" Paper Hone:
comb Sandwich Structures: Engineering Data,
by Jack eveaux, TD& T, Spring 1981.
-l Platforms that must withstand greater weigl
are normally specifically designed and would n<
be stock units.

5 These additional suppons were not pan of tt
original deOection testing, nor are their weigh
and costs included in the test results chan.
[

Stancil Campbell is on the Design Fa(
ulty at the University of Alberta, an
Technical Director of the Colorad
Shakespeare Festival.

Table of Contents for the Digital Edition of Theatre Design & Technology - Summer 1984