Post by nomuse on Sept 27, 2006 15:09:39 GMT -4
Got a problem I've run into before with flying scenery and was wondering if any of the other theater techies here had seen or tried solutions.
Specifics of this case; a 6' diameter "stained glass window" weighing approx 45 lbs, flying on two lengths of 1/8" aircraft cable. Because this is not actually a fly house, the cables run up to a pair of pulleys bolted just above the "out" trim height and thence to an improvised counterweight arbor.
Problem is, of course, if there is any hitch or jerk while flying in, or even significant vibration on the catwalk (such as the volunteer crew person moving about a little too vigorously), the window begins to pendulum on its twenty feet of cable. Rather distracting to the scene, as it plays just twelve feet above the DSC acting area.
Because of the restricted space, the scenic piece is its own batten -- so I can't do diagonals there. In the out position there is maybe six inches of cable left between scenic piece and pulley, so I have a pretty restricted area to work in there, too.
What I've tried;
A diagonal down by the unit, using a bit of thinner AC. Failure mode; the pivot point for the pendulum action merely moves up to the top of the diagonal brace.
Re-routing the operating line (1/2" cotton/poly in an endless loop containing the counterweight) to make it easier for the operator to move it without jerking at it. This has proved sufficient to get me past most of tech, and will probably be what I'll live with for the run.
What I've thought about;
A pair of damping springs in a diagonal, either secured to the cable right above the unit (thus in sightlines) or to a sleeve or free-running pulley just below the supporting pulleys. Theory is that as the unit swayed, the springs would gently tug at the line itself and slowly damp out the pendulum action.
Any ideas? Comments? Commiserations?
Specifics of this case; a 6' diameter "stained glass window" weighing approx 45 lbs, flying on two lengths of 1/8" aircraft cable. Because this is not actually a fly house, the cables run up to a pair of pulleys bolted just above the "out" trim height and thence to an improvised counterweight arbor.
Problem is, of course, if there is any hitch or jerk while flying in, or even significant vibration on the catwalk (such as the volunteer crew person moving about a little too vigorously), the window begins to pendulum on its twenty feet of cable. Rather distracting to the scene, as it plays just twelve feet above the DSC acting area.
Because of the restricted space, the scenic piece is its own batten -- so I can't do diagonals there. In the out position there is maybe six inches of cable left between scenic piece and pulley, so I have a pretty restricted area to work in there, too.
What I've tried;
A diagonal down by the unit, using a bit of thinner AC. Failure mode; the pivot point for the pendulum action merely moves up to the top of the diagonal brace.
Re-routing the operating line (1/2" cotton/poly in an endless loop containing the counterweight) to make it easier for the operator to move it without jerking at it. This has proved sufficient to get me past most of tech, and will probably be what I'll live with for the run.
What I've thought about;
A pair of damping springs in a diagonal, either secured to the cable right above the unit (thus in sightlines) or to a sleeve or free-running pulley just below the supporting pulleys. Theory is that as the unit swayed, the springs would gently tug at the line itself and slowly damp out the pendulum action.
Any ideas? Comments? Commiserations?