Cheeseborough Question

[willbb123]

The group currently in our space have rigged spotlight to our far box lighting position. I have spoke with the architect and the railing can hold the weight, so I'm not worried about that. We have "truss mounts" for them, so all they did was cheeseborough the mount to the pipe. My concern is that the truss mount is around a foot long, so they can only use one cheeseborough on it. I am worried that the spot might shift, then spin, and fall.


Should I be worried about the set up?

 

[gafftaper]

The picture is so poor it's hard to see exactly what's going on.

From a load rating point of view everything appears to be fine... from what I can make out in the picture at least. This is probably what the person who sat this up is thinking, and what they will tell you if you complain about their work.

However, that isn't the safety issue. The question is: Are all parts of this system being used to bare weight the way they were designed to work? I would have to say no. This is a major problem something designed to support 500 lbs one way can be very week if force is applied in a different direction. Would a safety first rigger consider this setup unsafe? In my opinion YES! Your fear that the spot might shift is a very good instinct. If it does shift, what happens to the components of the system that are not hanging the light the way they were designed to be used? Will they hold or will they fail? Unfortunately, there's no way of knowing if it'll hold because it's not rated to work like this... and the phrase, "There's no way of knowing if it'll hold" is not something you will ever hear coming out of the mouth of a real rigger. Safe riggers KNOW the right gear and use it the right way or they don't do it at all.

We are stepping into rigging territory so I'm going to have close this thread down before someone comes along and give dangerous advice. If you are reading this and have something you are dieing to ad to this thread send me your comment by PM and I'll ad it in. Senior team/Mods feel free to edit my post and ad your own comments.

 

[Footer]

I would be a bit concerned about asking an architect a structural design question, they usually can not answer that.

I would make sure the physical light is safetied off to the pipe as well, not just the yoke. Now, it would be possible to run another pipe at a 45 or something like that to secure it a bit better. However, I don't know what else is around there to secure to. I would keep a wrench around to make sure that thing is tight at all times. Spinning could happen. Also, if the spot fits into the yoke so that even upside down you could use it you are a bit safer. All in all, I would try to get it back onto the yoke if you are unsure about it.

 

[gafftaper]

I've had several people PM me wishing to comment. All are concerned that the current situation is unsafe. Several are concerned that the hand rail is not actually safe to hang from. I know that my handrails are safe to hang from because I spoke to the engineer who designed the theater and asked what their load rating is. Do you have that certainty as well? Standard handrail is NOT safe to hang from. ESPECIALLY like this.

All have suggested other ways of hanging the light that unfortunately I feel would cross the limits of the TOS to post. However, I think it's safe to give you some general strategy. It would be much better to hang the fixture below the handrail from two connection points. If that isn't possible then you would be wise to find a way to incoporate the floor. You could either attach some pipe from floor to the rail, or just build a floor stand that allows the floor to support it completely. Unfortunately the TOS doesn't allow me to tell you how to do these things.

 

[ship]

Your plan of two points or spud mount type pipe sounds good to me. A Cheseborough normally designed for 2" aluminum pipe but can at times as assumed do 1.7/8" Sch.40 1.5" steel pipe in hanging a light but I would say not persay prevent it from slipping either on axis of the mounting bolt given a single clamp or in rotation given a friction coeficient by way of tension on the clamp verses serface area of the aluminum clamp verse the size and type of pipe clamped to.

Long story short, if a clamp designed for holding to 2" O.D. aluminum pipe is used to clamp to a 1.7/8" steel pipe in this way, no matter how much you dog down on that clamp in possibly causing it to fail, you cannot achieve sufficient surface area on the clamp to prevent it from moving should the weight of a pushed follow spot be on it in an usupported way. This much less various blots mounting fixture to pipe if left able to swivel by way of tension could loosen as a possibility.

Can support the weight yes, best way to support the movement of the fixture no.

I was intially thinking span two clamps by a piece of steel or aluminum which at its center the fixture mounts to by way of fiber or teflon washer between fixture yoke and plate. I better like your idea of hanging from both top and mid-rail as I think I understand it. Say some form of L-shaped steel which by cheseborough mounts to both rails and has on the L' the fixture mount. Not going to move at that point and more within the concept for the clamp for holding to the pipe.

This concept if even Unistrut and Unistrut hardware making it up with the clamps installed on it would I think work better.