Fly or rigging system: allows safe support and quick change scenery and lighting used in proscenium theatre.
Part of Carpentry, involves own set of skills so is almost a separate department. The flys are run by the flymen, and under the control of the Head Flyman.
Systems come in several forms.
Earliest form: Rope/"hemp" system.
A system borrowed from sailing ship industry, majority of terminology including the term "rigging" itself comes from sailing ships.
Pinrail
--Borrowed from square rigged ships, a wooden rail with holes for
belaying pins, where ropes are tied off.
Usually double tiered rail.
Lower bar used to tie off scenery at low trim.
Pin rail located at floor level or on catwalk above floor; flyrail.
Today main system is rarely a rope system; but often included
as auxiliary system.
Used for temporary or custom rigging; rope systems easier to adapt than
counterweight or winch systems.
Well equipped theatre often a flyrail on both stage left and right.
Scene loft or fly space: large open area located above stage; curtains and flown scenery stored here.
Gridiron, or Grid for short, on which are
the pulleys for the fly system.
Pulleys also called Blocks, a naval term for
pulleys on a ship, or Sheaves.
May sit directly on the grid with pulley (wheel) up, called Overhung,
or be fastened above grid to the ceiling, pulley hanging down, called
Underhung.
Often main loft blocks located on pairs of heavy support
beams with a gap between, called loft block well.
Floor of channel irons fill area between.
Channel irons can supporting lightweight temp rigs, called spot
lines.
Grid may be made of subway grating or similar lightweight metal grate; old theatres the grid and beams were of wood.
In some theatres built on the cheap the grid dispensed with;
rigging is underhung from the ceiling beams.
Makes maintenance difficult and temporary rigging almost impossible.
Head blocks: above rigging rail, a set of
loft blocks where multiple lines from rail spread out over grid to
individual loft blocks.
Head blocks usually multiple blocks, i.e. a single block with several
grooves or pulleys, or may be a set of individual pulleys used in
association. Last scheme occasionally found in older hemp houses, but
rarely used today.
Headblock well: massive I-beams designed to
resist both vertical and horizontal loads.
Pull on the headblock well consists of ALL the weight on the fly system
both down to the rail and across the grid sideways to the loft blocks.
If not accounted for, sideways pull can bend headblock well open,
causing headblocks to collapse down the well.
Traditional material for rope systems was manila hemp rope,
usually 1/2" or larger.
Replaced by polyester double-braid rope; stronger, stretches less,
reacts less to humidity, rot proof, no slivers.
Weight of scenery, curtains, lighting on battens can be
tremendous; needs counterweight.
On rope system, done using sand bags, secured to the purchase lines
with clew, cast iron clew or wire rope sunday.
Sandbags come in standard increments, e.g. 10, 25, 50, and
100 lb. when filled with dry sand.
The weight of the sandbags must be slightly less than the load on the
batten but must be nearly weight of load so the flyman can control
easily and safely.
At trim, the load is held in place by tying the lines to
pinrail.
Sunday is just below headblock when batten is in.
Note: a batten can never fly out higher than the distance between clew
and pinrail when the batten is in.
A
metal frame, called an arbor, is raised and lowered
by an "endless" purchase line passing over headblock and under a
floating block beneath rail.
Purchase line passes through rope lock mounted on rail.
Set of wire ropes attached to top of the arbor (usually aircraft cable)
are loft lines.
When line beneath arbor is pulled down (usually the rear line), pulls
arbor down, raising the batten.
When other (usually front) line is pulled, raises arbor, lowering the
batten.
The arbor is kept in line of travel either by "shoes" engaging a T-track, or by guide wires. The first is called a T-track system and the latter a Wire guide system.
Metal counterweights are placed on bars of the arbor to
balance load.
This weight ideally should exactly balance load on the batten so that
the endless purchase line can pull the arbor both up and down.
Pipe weight: part of load representing weight of the empty batten; should be left on arbor when load is removed.
Trim chains: chain lengths attached to the batten end of lift lines in a counterweight set. Pipe battens at trimmed to level by adjusting these.
Counterweights are usually iron or steel, cast or flame cut from heavy plate.
Counterweights are often referred to as "bricks" or as "pigs"
(for pig irons).
Come in semi-standard sizes, e.g. 10, 20, 30, and 50 lbs.
Cast weights usually made to an actual weight. Cut weights may be
uneven size, such as 26 or 38 lb., since they are often made to an even
dimension rather than an even weight from a standard thickness of plate.
Lead is cast, perhaps as a 30 lb. brick (about 1/2" thick). A
similar size steel weight will be about 15 lb. or so.
If both lead and steel weights are used, place leads on top of the
steel but not visa versa; lead may flow from beneath the weights above
them.
Two main flavors: Single purchase and Double purchase.
The Single purchase simpler, more common.
The arbor/purchase line travels between floor and ceiling; arbor
travels one foot for every foot the batten travels, must put the same
amount of weight on the arbor as the load weighs.
Everything, travel and weight is in 1:1 relationship.
The main drawback: one entire wall must be dedicated to the system; full floor to ceiling travel of batten requires full floor to ceiling travel of the arbor. The system doesn't work well from a fly rail, as pipe is at mid-travel when arbor is at rail.
Double purchase system: similar to reversed double pull block and tackle.
In Block & tackle, rope doubles back through a floating pulley: 2 feet of rope is pulled for every 1 foot of rise of load, but your need only pull half as hard. The load is twice the weight of the pull, and moves only half as far.
A double purchase system is similar, except that the load is
on pull side, and arbor on the load side.
Arbor moves only one foot for every two feet of travel of the batten;
can therefore be run from a flyrail located halfway to the ceiling, and
still allow the pipe to come in to the floor.
The major drawbacks: needs twice as much counterweight on arbor as there is on the batten (2 x the weight, 1/2 the travel).
Loaders typically must handle larger weights.
A single purchase "single" brick typically weights 20-25 lbs.; for
double purchase a "single" brick weighs 40-50 lb., and a "half" brick
weighs 20 lbs., the same as a single purchase "full" brick.
Double purchase systems cost more, are more complicated to use
and maintain, and must have twice as much weight on hand for a full
compliment (weighs are naturally sold by the pound, or ton).
Also, flymen can't double as deck hands because they are on a catwalk
overhead.
Another place double purchase can be useful is where the side
walls are lower than overhead grid, as with a grid located partway up a
gable.
A single purchase would not allow full travel floor to grid, but double
purchase with "muled" headblocks and loading rail halfway to the
ceiling would allow full travel of the batten.
Primary advantages: can be run remote control by single
operator. Using a control console, the operator can select and run
several line sets at once.
Some forms of winches can handle far heavier loads than could be
operated manually.
Drawbacks: more expensive per lineset than other systems.
More complex than other systems and so need more frequent maintenance.
Lack "feel", operator is disconnected from the piece being run and has
no direct sense of when trouble is happening. On a counterweight or
rope system, you can FEEL when lineset fouls or hits something. First
indication on winch may be when something breaks.
BUT, for very large loads (electrics bridges and moveable ceilings) winches can be superior.
Winch systems come in several forms.
Chain motor rig:
A form of almost-synchronous winch system that is commonly used for
show rigging.
Chain motor rigs consist of industrial chain hoists, typically one or
two-ton models, used in sets to lift trusses or other loads.
In general industry, chain motors are designed to be hung from ceiling,
and the chain is lowered for the load.
Theatrical chain motors are often attached to load, and the chain
hook is attached to ceiling, a condition referred to as "inverted".
Originally, chain motors were designed to be run "normally" and required
modification to be run "inverted" i.e. chain up. Modern chain motors
usually work in either orientation. Perversely, in the theatre industry
a motor hung with chain up is considered "normal", so motors hung chain down
may be referred to as "inverts".
These motors are fairly consistent in speed over their entire
load range, and are single speed only. They usually run at about
16 ft./min. They are NOT identical, but they can work because:
a) they are set up and taken down regularly so that the accumulated
errors don't add up.
b) they can be run both individually and together, so that single
motors can be adjusted to line up with the others.
Disadvantages; motors get out of synch quickly, are noisy, and slow.
BUT, chain motor rigs allow you to fly heavy loads (in multiples of a ton) with a system that can be quickly set up anywhere the overhead can support the load and accommodate the chain attachment points, including outdoors with a ground supported roof trussing.
Large single motor and shaft which raises all the lift lines on a batten or truss.
These are used for most motorized electrics and lighting bridges,
a form of truss work specifically intended for supporting permanent
electrics and which sometimes including a catwalk for focusing. It is
also used to lift the large lineal loads.
This system is big, heavy, noisy, and slow, and runs at one speed only,
BUT does allow the safe movement and support of heavy loads without
the need for counter weighting.
Synchronous winch system:
One winch for each line on a load, all controlled by the same control
signal.
Each motor MUST be exactly identical in speed to the others in the
system; otherwise motors get out of synch fairly quickly, and the pipe
will come in crooked.
Systems are usually single speed, as it is difficult to create a motor
with variable speed AND uniform lift capability. Running a motor at
slow speed also lowers effective power, so the motor will stall under
load.
Biggest drawbacks: expense of all those motors and the ease with which
they get out of synch; even a small variance accumulates over several
runs.
The most common use: multi-use auditoriums where ceiling can be re-configured for different acoustics. These work because the loads are predictable and the motors are carefully tuned.
Automated rigging system:
Each lineset consists of a variable speed motor attached to a shaft with
cable drums attached. The cables in turn go to loft blocks. These systems
are computer controlled, and so "automated". They combine the advantages
of single-shaft systems with the variable speed capabilities of synchronous
winch systems. The addition of computer control means that rigging moves
can be recorded as a series of cues and played back in order by a single
operator. Also, the need for handling counterweights is removed, providing
loads are within the capabilities of the system. On the minus side,
programming cues for a show takes longer, and maintenance is both more
critical and more complicated than "manual" systems, involving as it does
both mechanical and computer systems working together. Automated systems
remove a sense of "feel" from the operator that is part of manual rigging
systems, and so require safety controls to be built in that can "sense"
a problem and automatically halt the rigging system in the event of an
emergency.
Special purpose temporary rigging sets, usually with one lift
line holding a single object, such as a chandelier. A loft block is
placed in position and a line dropped where needed.
Often rigged as cable picks (pickups to carry bundle of electric cables
offstage).
May be rigged for line sets in out of ordinary positions, as for
battens run diagonally across the stage.
Spotlines are typically rigged using rope system rigging, but can be
set up with any system: chain motors, winches or counterweight arbors.
