Teach @Dagger Rigging.

As I mentioned in another thread, go and buy Harry Donovan's Entertainment Rigging RIGHT NOW. It's expensive, but if you really want to learn this stuff, it's the single best investment you can make in your personal education. Other books such as Glerum's go into more detail about the theory and mathematics behind rigging, but Donovan's is really written for a blue-collar worker - literally hundreds of very clear diagrams, easy-to-understand procedures, and much more grounded in actual "boots-on-the-ground" knowledge than just theory. I just leafed through my copy and found DOZENS of diagrams of different ways to construct bridles, as well as pages and pages of advice for how to deal with a wide range of rigging challenges. Let me be clear - this book is NOT a substitute for hands-on knowledge and learning from actual people in actual situations. But you can find the answer to nearly every question you've posed over the last few days in this book, and reading it will allow you to have a much better understanding of what you're learning while on the job.

And also, just so you know that we're not all being mean by holding out on you, bridles are tools that vary based on the application and venue. Just as you wouldn't get responses to "send me a good lighting design for Beauty and the Beast", there's no one correct way to make bridles. Yes, there are fairly standard ways to do it when you're blessed with excessive trim heights, no weight restrictions, and unlimited gear, but it would be foolhardy, not to mention unsafe, for you to look at a bridle from a 100' arena and try to use that in a 20' gymnasium. Pick up the book, learn the theories behind his diagrams and approaches, and then you'll have a much better idea of where to start when planning your own rigs.
 
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...Never seen a truss used like that apex should be on the sides not on the top , am I correct?
Normally yes, but I believe the truss in question* has diagonals on all four surfaces.
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BTW, I don't think "apex" is the correct term, as that usually applies to one of the point of triangular truss.


*If I'm not mistaken, manufacturer Arcofab, as used by Solotech and Christie Lites, among others.
 
If whoever put the spanset on actually took the time to backup the spanset with steel I highly doubt they choked the truss sideways. That is photo proof that someone out there does backup spansets...
 
I stopped using nylon only spansets a while back for this application, steelflex is all I use. How do you all feel about the use of a backup steel when steelflex is used? Redundant?
 
I just
Ordered the book and should be here anytime next week ! Very excited , expensive paid $240
Rochem's link had it for $94, after converting to Canadian dollars, thats still almost double. Must be some expensive shipping.
 
1)no pics , but same venue ( like the pic I posted in other threads with roof truss)

this time it was deadhang ( 5ft steel and chainfall )

because of the dead hang the chain was rubbing against the low steel when pulling chain up/down.

I thought it was wrong.

I have seen gigs where in order to keep the chain away from the low steel being done like this

( no pics but I made a drawing, )

drawing is off should be a chainfall
 
choke on low steel and then up over highsteel attaching a chainfall ( grey circle is a choke0
 

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2) 6ft spansets were used on truss but no backing it up with 5ft steel..... because the whole truss was safety with 10ft steel on low steel

what you guys think?
 

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First of those safeties are useless. Second choking low steel and wrapping up and over high steal (in what I'm guessing is a standard expo hall rafter) doesn't eliminate the chain rub. What I like to see is a stinger that drops the hook below low steel so what is rubbing is steel cable on steel beam with a piece of burlap between. (5/8" Steel cable is much stronger side loaded than CM lodestar chain.)
 
First of those safeties are useless. Second choking low steel and wrapping up and over high steal (in what I'm guessing is a standard expo hall rafter) doesn't eliminate the chain rub. What I like to see is a stinger that drops the hook below low steel so what is rubbing is steel cable on steel beam with a piece of burlap between. (5/8" Steel cable is much stronger side loaded than CM lodestar chain.)

If using he 10ft steel for safety around low steel is useless

How should the safety be for the truss?
 
The problem with suspending off of the bottom chords of truss is that all of the load is being hung off of the welds between the bottom chords and the cross braces. The top chords receive a minimal amount of the load and serve little purpose in this configuration. Whereas if you suspend from the top chords, the load is evenly distributed across all members of the truss because the top chords allow the forces to compress down the bracing, be reinforced by the bottom cords, and while diluting the loads across all of the welds. Not just the bottom half of them.

Think of it this way. If your production truss fell out of the air and got caught by the safeties, would you rather the shock load be applied across the entire frame of the truss or would you rather it just yank on the bottom welds of it?
 
The problem with suspending off of the bottom chords of truss is that all of the load is being hung off of the welds between the bottom chords and the cross braces. The top chords receive a minimal amount of the load and serve little purpose in this configuration. Whereas if you suspend from the top chords, the load is evenly distributed across all members of the truss because the top chords allow the forces to compress down the bracing, be reinforced by the bottom cords, and while diluting the loads across all of the welds. Not just the bottom half of them.

Think of it this way. If your production truss fell out of the air and got caught by the safeties, would you rather the shock load be applied across the entire frame of the truss or would you rather it just yank on the bottom welds of it?

If I understand correctly
Safety should be wrapped around the high steel and around the top cord of the production truss ?

(Not wrapped around low steel)

Is that correc?

What about the production truss ,safety around top only cord only is okay? Or should the safety be wrapped around the whole production Truss ( top cord and bottom cord) if so i can see the safety sliding out of the production truss .
 
Any safety should be configured in a manner where there is almost no shock load. Basically, the safety should instantly pick up load should the primary fail. In my training class I show an example of a very specific set up where I demonstrate that a poorly implemented safety will fail.

Another thing about J-bar roof trusses is that they have almost zero lateral stability. Bridling off of them perpendicular to its major axis is a no-no.
 
I commend your interest in rigging. As stated in this and other threads, the internet is NOT the place to learn rigging. I HIGHLY recommend you take a rigging course if you are actually interested in doing rigging.

However there are several good books to read if you are interested that will get you started. Hands on practices cannot be taught though a book or internet post or video, and they are critical to proper and safe rigging.

There is MORE THAN ENOUGH bad rigging out there to begin with unfortunately. So good on you for trying to see if things you have seen are safe, or proper. Perhaps a thread "Rigging I am pretty sure is no good", but I am really not sure what the administration would think of even that.

It is CB policy that no rigging instruction is to be given on this board for the above reasons. The best riggers could try and describe what to do, how to do it and why. People would then read that, think they know what they are doing, and put peoples lives (and property) at risk.
 
I am looking for explanations rather than instructions from now

Looking at this pic and from what Posts I read I come to my conclusion ( correct me if I am wrong)

- using pipe or in this case a ledger

It has no strength because there is no top and bottom cord and no connections between them . As well as the pin in the Rosetta comes lose and both ledger disconnects
Is that correct ?


But what I really want to know is in this configuration how much weight is the motors taking and how much weight each point of the ledger ? (let's assume it's a truss instead of a ledger and assume the points on ledger are symmetrical)


Ex . say the video wall weighs 500lbs
So each motor is taking 250 lbs

But how to calculate each point on the ledger?

Starting from left to right

1st point =35 lbs
2nd =95lbs
3rd=75lbs
4th=90 lbs
5th=75lbs
6th=95lbs
7th=35 lbs
( according to the chart )
Because the 2nd and 6th point are the heaviedt the motors are placed closest to them ?

Is that correct?
 
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