Design Stabilize bouncing fixtures in catwalks

[theatre4jc]

My facility has a large balcony that is built with canter leaver system. Great design with few columns and looks great in the room. However that means my catwalk system (6 cats) is connected to the balcony. Me alone standing in the balcony can jump and cause equipment to bounce. I have some VL3500s aimed at a wall behind the preacher with a slightly out of focus gobo shuttered to the area I want textured behind him. Usually the bounce from the cat/balcony is minimal but today it was constant and is annoying. I'm looking for a way to stabilize this, almost like a shock absorber. The RSC LightLock will not fix the bounce but I want to find a way to absorb the bounces through the rigging and that way the light will main still. It is mounted onto a pipe that is cheeseboroughed to the catwalk. It is a horizontal bar with a angle brace providing the extra support creating a scalene triangle.

Couple questions, 1 does anyone know of a device that would fix this? 2, if no device exists would this be something that is needed by others in the industry that could justify the time and money to engineer something?

 

[FMEng]

It sounds like you need a structural engineer to examine the situation. It seems to me that one person should not be able to significantly shake the balcony, so I would be concerned for the safety of it. Mistakes can be made in the design and construction of buildings, and they can lead to outright structural failures. Even if the balcony is safe and just naturally moves a little, I should think that the catwalks could be disconnected from the balcony in such a way to decouple them from movement, and the SE is the person to help you do that.

 

[DuckJordan]

Actually our Catwalk shakes as well. Its fairly common in wide spanning catwalks that have to be secured to the grid and not the walls as well. Our Mezzanine seating used to bounce when we had a concert in due to people dancing to the music. It was completely safe we had several structural surveys done and it was designed to swag and bounce a bit to help keep the beams from cracking under the stress.

 

[MNicolai]

I think the problem is not that it shakes when people are walking on the actual catwalk, but that the audience can cause it to shake from movement in the balcony -- very undesirable when that VL3500 is pointed at the preacher and suddenly starts shaking up and down as people move around in the balcony.

I agree with FMEng that this sounds like a thing you'll need a structural engineer for. Either by reinforcing the balcony so it's less sensitive to movement, or by attaching the catwalks to something else. Either way, it will likely not be an inexpensive project.

 

[chausman]

Actually our Catwalk shakes as well. Its fairly common in wide spanning catwalks that have to be secured to the grid and not the walls as well. Our Mezzanine seating used to bounce when we had a concert in due to people dancing to the music. It was completely safe we had several structural surveys done and it was designed to swag and bounce a bit to help keep the beams from cracking under the stress.

http://www.controlbooth.com/forums/safety/21859-bouncing-balcony.html

Pretty common. There are places in one theater that bounce just from people walking to their seats.

 

[emoreth]

Yeah, we actually had to move our projectors cause they were originally balcony-mounted and couldn't take the shaking. One person running would make them vibrate visibly.

Have you considered mounting static battens near the catwalks but having them supported by something else? It might not be possible, but if it is, it'd probably be a lot cheaper than re-engineering the catwalks.

 

[derekleffew]

...Couple questions, 1 does anyone know of a device that would fix this? 2, if no device exists would this be something that is needed by others in the industry that could justify the time and money to engineer something?

I don't know of anything. I'm thinking some sort of rubber or neoprene isolation pad. It seems like something in which The Light Source may be interested. I wondered if these or similar could be adapted: Vibralastic‡ Isolation Mounts ?

 

[StNic54]

If you come up with an anti-shake feature for VL's, please patent it as quickly as you can - you'll make everyone in the cruiseline industry very happy.

 

[jglodeklights]

If you come up with an anti-shake feature for VL's, please patent it as quickly as you can - you'll make everyone in the cruiseline industry very happy.

It actually would not be that difficult taking into consideration that Nikon developed an application of this technology for the photographic market back in the early 1990's, and that similar scale systems have been used on airplanes and helicopters for quite some time. However, it would likely be less effective on land and in calmer waters, where the system could often create false compensations; similar to not being able to use image stabilization on a tripod.

I really need it for my template washes from fixtures mounted to my vertical grid mounted to the fly loft. The one flyman is a bit of a buffalo and it doesn't help that there isn't much space especially when all the pieces are at out trim as we work in a hemp house. #sandbagproblems

 

[Syphilis]

Howdy folks,

I'm in search of vibration damping C Clamps.

The scenery in this production has been tied off to a tension grid, so that when actors walk on certain platform all the IQs do a dance. I've seen this type of clamp on speakers before, and I'm wondering if anyone has recommendations for specific models, or if there are other home remedies for reducing vibration to an instrument.

Thanks!

 

[KeepOnTruckin]

This may not be a direct solution, but it works with 1.5" pipe.
Nigel B Design has an excellent line of vibration isolators intented for pole mounted projectors and cameras. I've used these to prevent a pole mounted projector from shaking when the hvac makes the whole ceiling shake or someone slams a door nearby. I havent tried it in a lighting situation but I wonder if it might be of use

http://www.fullcompass.com/prod/197704-Nigel-B-Design-NB-UIM-52