What is a stage weight?
A stage weight is a heavy metal plate used in theaters and event spaces either as counterweight in a fly system or as ballast that holds down stage braces and scenery. In a fly system, stage weights are stacked in an arbor to balance whatever hangs on a batten, which lets one person move heavy scenery by hand.
Metal stage weights largely replaced the older practice of using sandbags as counterweight. In the US you'll also hear them called arbor weights, counterweights or bricks.
How a counterweight fly system works
A batten (a long steel pipe) holds scenery, lights or drapes above the stage. Lift lines run from the batten up to loft blocks on the grid, across to a head block at the side wall, and down to a steel frame called an arbor. Stage weights stacked in the arbor balance the batten's load. An operator at the lock rail pulls the purchase line to fly the batten in or out, and a rope lock holds it in place.
Parts of a counterweight system
- Arbor
- The steel frame that holds the stage weights and travels up and down a track along the side wall.
- Arbor rods
- Vertical rods on the arbor that the weights' notches slide over, keeping the stack in place.
- Spreader plates
- Plates placed in the stack at intervals that lock the arbor rods together so they can't bow apart.
- Batten
- The long pipe that scenery, lights or drapes hang from.
- Line set
- One batten plus everything that moves it: lift lines, blocks, arbor and purchase line.
- Lift lines
- Wire ropes that connect the batten to the top of the arbor through the blocks overhead.
- Loft and head blocks
- Sheaves (pulleys) on the grid that redirect the lift lines toward the side wall and down to the arbor.
- Purchase line
- The hand line the operator pulls to move the arbor and batten.
- Rope lock and lock rail
- The lock clamps the purchase line; the lock rail is the row of locks where operators work.
- Loading gallery
- A raised platform where crew add or remove weights when the batten is at its lowest point.
How to identify the weights you have
To buy weights that fit, measure one you already have. Record its length end to end, its width, its thickness, the width and depth of each notch, and its weight on a scale. Note any maker's name stamped on the arbor. With those numbers, a supplier can match the pattern from stock or fabricate new pieces.
Safety basics
Counterweight rigging moves heavy loads over people's heads, so procedures matter. A few principles every crew should know:
- Load the batten first, then the arbor. Unload the arbor first, then the batten. This order keeps the arbor from becoming heavier than the batten and running away.
- Never exceed the arbor's rated capacity.
- Install spreader plates in the stack as the arbor manufacturer specifies.
- Keep the loading gallery clear, and never leave loose weights where they can fall.
- Have the system inspected regularly by a qualified rigging inspector.
Follow the standard
In the US, manual counterweight systems are covered by ANSI E1.4-1, Entertainment Technology: Manual Counterweight Rigging Systems, published by ESTA. This guide is general information, not rigging training. Follow your system manufacturer's instructions and get hands-on training from a qualified rigger.
Common questions
How heavy is a stage weight?
It depends on the arbor it was made for. Common arbor weights range widely; we stock them from 17 lb to 64 lb. Weigh one of your existing weights and measure it to find the size your system takes.
What is the difference between a stage weight and a sandbag?
Both can serve as counterweight, but steel stage weights have largely replaced sandbags in counterweight fly systems because they are compact, consistent and stack securely in an arbor.
How many weights fit in an arbor?
Every arbor has a rated capacity set by its manufacturer. Never load past that capacity; if a load needs more counterweight than the arbor can hold, the line set needs to be re-engineered by a qualified rigger.
Why do theaters run short on weights?
Weights get moved between line sets, borrowed for floor ballast and carried off over the years, and new loads like LED walls are often heavier than what the original system was set up for.
Sources and further reading
- Stage weight, Wikipedia
- Fly system, Wikipedia
- ANSI E1.4-1-2022: Stage rigging systems, ANSI Blog