Stage Rigging:
homework #3 recap:
Design Factor
Min. DF
static wire rope = 5
moving “running” wire rope = 8
fiber rope = 10
Last Week Recap:
knot= 50% efficient
WLL of rope x .5= WLL w/knot
THERE WAS A POP QUIZ!
Counterweight Rigging:
Single Purchase
http://www.ia470.com/primer/images/cntrwt.gif
top & bottom of arbor =purchase line
whenever a load is on the batten, you load that much on the counterweight arbor.
i.e. if arbor goes up 5′, the batten goes down 5′ Ratio= 1:1
Rope lock – only designed to hold 20-30 lbs of out of balance load.
*not designed to hold out of balanced load
(also rope lock is part of a longer system called lock rail.)
Loading Bridge= catwalk, where you go to load counterwreights to arbor.
-optional, but not all theaters (unfortunately) have them.
– common
*When there’s no loading bridge it’s shitty – very labor intensive
mid rail= jump floor
– there’s a pin rail so you can do spot rigging
– if something is out of balance, you can load a counterweight
– helps a lot of things go smoother,
Any weight above pipe weight = balance out the equipment
limit capacity of arbor = how tall it is.
Double Purchase:
https://wiki.vpa.mtu.edu/wiki/images/2/2b/Arbors.gif
(Similar to the Single Purchase system except the arbors are different, as seen in the picture above.)
-design to solve for a space problem
– you need half as much travel for arbor
1′ arbor = 2′ batten
1lb. batten = 2lbs. arbor
Drawback of Double Purchase = more weight = difficult to start.
Wire Rope – rope made of steel wire
In fiber rope – strands are twisted together
# of strands= how you designate wire rope
6 x 19 1WRC Aircraft Cable
where the 6 = # of strands
& with the 19 – the higher the # more flexible, and the lower the # the more durable
Fatigue Break – constant bending of less flexible the material resulting in breaking of the material
w/ pulleys:
Ratio: d/D, where d= diameter of cable, & D= diameter of sheave
d/D= 30+ = ratio for steel cable
Wire Rope:
Termination- how you attach it to something
1. Swage (Sleeve/Nico) Preferred
– copper sleeve down on the cable
-advantage= 100% efficient when done correctly
NOT ADJUSTABLE
also preferred = eye to eye/ jaw to jaw turn buckle, where the jaw to jaw removes shackle from system
Turn Buckle – made to adjust, in or out, one is right hand thread, & the other is left.
– used alongside wire rope
*Go/No Go Gauge*
NO ALUMINUM sleeve for overhead rigging
2. Crosbies/ Wire Rope Clip
-specified torque settings
-try to avoid because people are not aware of the correct methods needed when using them.
Advantage= ADJUSTABLE!!
– 80% efficiency
