How fast should I run?

[Skervald]

I have a renter who would like to hang this from a bar joist in my black box. He claims it weighs 150lbs.

We don't do a lot of rentals and I've never had anyone ask to do anything like this so we don't have a policy in place. I'm really not comfortable letting someone [read: not a certified rigger] hang some 150lb. home made contraption over a crowd of people.

To the question: How do you deal with this kind of request? A simple, "no, you can't do that" or "it must be inspected and hung by a certified rigger at your expense".

**this is my first attempt at inserting a photo into a post. I apologize if it didn't work. I will do my best to fix it quickly.

 

[viking33]

If those balls are as big as they look (24" on the outside perimeter) then its more then 150lbs. Its your space so what you say goes. If you want to be nice about it you offer for it to be certified.

 

[EdSavoie]

Jesus Christ!

I'd say having it inspected first is putting it nicely...

 

[TheaterEd]

It's a hard no if they're asking me...

 

[cbrandt]

Checking out the additional safety cables holding up each arm, it doesn't even look like it can support its own weight. That things needs a heck of a lot of inspection before it is ready to hang over someone's head.

 

[Footer]

Well.... first that thing is pretty damn cool. Would love to see it all spin.

With that... who built it? It looks like it was done by someone who has half a clue. Unistrut and such. Have them give you a drawing with how they intend to rig it. A real drawing. If its being hunt on less than 8 points then you have an issue. Depending on the kind of strut they are using how you load it really does matter. http://www.unistrutohio.com/techtalk/beam-and-column-load-tables-for-unistrut-p1000-and-p1001

I would want to see a clean point hit at the center of each of those arms. Also keep in mind a 24" mirror ball weights around 25#, so right there you are over their weight and you haven't added the structure yet.

Its doable. I would have them do some more work to give you good drawings. Could you also give us a bit more insight to what you have in your space to hang from?

 

[Amiers]

That looks very cool. I am going to say that it was made by someone that does know what they are doing but the cables holding it we're not included. I am suprised the garage hasn't fallen down since one cable wrapped are the main garage door beam.

Like was said drawings and actual weight and a point for each arm and suggest proper AC cables terminated from motor to ball or point to ball with rated shackles and not what looks like cheap quick links.

If you do install this please take a video of it in action lights and all cause it looks like it would be a great effect.

 

[theatricalmatt]

I think I'd rather see it welded as one piece, rather than sections of unistrut bolted together. Makes it more difficult to transport but much stronger. The pick points supporting the individual arms should be closer to the ends, and more uniform in placement. Seeing custom swaged eye-to-eye steel rather than what look to be re-purposed lighting safeties would also help. Knowing they were rated shackles, properly moused, would also be a reassurance. Lastly, some backup steel as a safety for the entire armature is in order.

It does look.kind of cool, though! Bet it'd look great with a bunch of pinspots, or even a laser or three.

 

[EdSavoie]

How about 10W lasers?

*Sizzle Sizzle*
"Is that burning the wall over the- Ah my eyes!"

 

[Skervald]

I have to admit my desire to see this thing in operation is the only reason I didn't give an immediate, "no". I was pretty well decided that was the answer before I posted here but I'm glad to see there is general agreement. They want to hang it from regular bar joist that looks something like this:

(the above photo is not in my space but the joists are very similar)
The weight of the thing spread out over multiple points would probably be okay but I don't have a load limit from a structural engineer and I'm not willing to stake human life on "probably". Also, given the spider-like layout of the thing, it would be difficult to get a hang point exactly where it needed to be. The renter is a local DJ (who, with my luck is probably reading all of this). I don't know a lot about his background but my guess is that all the materials came from a big box store. I would be surprised if any of it is rated.

 

[StradivariusBone]

With the unistrut "arms" it would be a simple task to put forged eyebolts to create points to hang the strut from. That's how it's used in most industrial applications with threaded rod anyway. I'd do some homework on deflection of unistrut and how much can be supported in cantilever applications. Also if channel up or down makes a difference in strength. I can't recall seeing unistrut used as a cantilever, so I would at least want to find out about it. Seems reasonable that 25# on one end shouldn't matter too much so long as it's not too long of a lever.

I'd also be curious to see how he bolted the motors of the mirror balls to the strut and if there are any safeties to the motor housing and the frame or just single-point. Finding enough points to hang this from would be tricky and if it's just a beam, then bridling it comes into play which gets more math-y than I'm personally comfortable with. That hits the point where I'd call a better resource, at least for me.

 

[JohnD]

I was wondering what the trim height is for your black box?

 

[Skervald]

Just a hair over 17' to the bottom of the bar joist and just over 21' to the deck above. I think I know where you're going with this and I thought the same thing. How tall is that contraption?

 

[JD]

Crazy darn thing! I would be far more worried about the structure of the device itself. Looks like the multiple rig points are because the uni-strut cannot support itself. Can't say I didn't see crazier things in all the years of doing rock shows, but the qualifier was that any contraption should at least be self contained. And then there is this- "home made contraption over a crowd of people" It just sounds like part of the news headlines the day after someone gets hurt or killed.

 

[Van]

By my count that unit is WELL over 150#.
I can see a lot of places to make improvements on the rigging of the item but as others have pointed out I see nothing inherently 'wrong'. As long as that is not light-duty strut, which is hard to tell from a picture. As long as decent points are made 1/2 - 3/4's of the way down each arm and in the center, there is no reason this shouldn't fly.
The only caveat to that statement being that it better be well built, redundancies built in to the engineering, all esna nuts all the motors bolted not tapped into the strut.

Apparently these guys got all those mirror-ball motors that were supposed to go to Tunisia.....

 

[JD]

Apparently these guys got all those mirror-ball motors that were supposed to go to Tunisia.....

Ha! You saw that post too! He never did check back in, but at least this guy figured out the "spinning" part

 

[kicknargel]

I'd say that since you personally are not comfortable saying this is OK (hence posting here), you should not say it's OK. Requiring evaluation and installation by a certified rigger is 100% reasonable, and make sure it's clear that the rigger's decision stands, and the client needs to pay the rigger whether or not the piece gets hung.

 

[ruinexplorer]

Many places that I have gone in require a secondary insurance for flying pieces, usually doubling the original. I don't know what your rider is like, but that might also help him change his mind.

 

[Dionysus]

Honestly when the guy who built it says it was 150lbs, and we can determine that the mirror balls alone are OVER that (thus he did not build it with the actual weight of the balls in mind) I'd give a flat out "NO". With the caveat that I'd give a yes if he got it inspected and passed by a repuitible source.
That thing can certainly come apart and fall on heads.