Dead Hung Batten - Threaded Rod v. Wire Rope Cable

[MNicolai]

We've got a project coming up where we're dead hanging a batten somewhere. The WLL of the 70' batten is supposed to be 1200lbs or so.

For the rigging part of the package, Company A bid $n to do exactly what we asked/expected, which was wire rope cable for the lift lines.

Then Company B bid $n-5k to do an 80' batten instead, but with threaded rod as the lift lines. They claim it will reduce swing in the pipe, but the absolute last thing we care about is swing in this pipe. We're going to hang some LED fixtures on it and then never get near the pipe again.

Given that information, do they appear equal bids in merit/design or should we be cautious about one design approach over the other?

 

[jglodeklights]

Done properly, threaded rod is actually an extremely strong and durable, especially when painted/sealed properly to prevent corrosion.

As long as an additional 10 feet of pipe isn't a problem, which I'm guessing they have specified as necessary to properly rig the pipe in your space, Company B makes sense. Less 5 grand with more space you could use. You say one thing now, but in 2, 5 or 10 years, when you need that one leg and slight jog DS to mask that area because the set/scenery is weird............

 

[SHARYNF]

Famous last words "we are never going to get near it"
NEVER HAPPENS if it is there someone will come up with some additional use for it

Sharyn

 

[egilson1]

The thing to be careful about with threaded rod is your terminations at either end. A lot of time people use unrated hardware to connect to the structural steel and batten. I would make sure you get a cut sheet of each component of the "lift lines".

Regards,
Ethan

ETCP certified Rigger, Arena & Theatre

 

[What Rigger?]

Hard to make any kind of a call on this without being in the space itself. I get the quivers whenever I hear "never going near it again" like SharynF says.

'Cause somewhere along the line, somebody else will. Eeeek!

 

[MNicolai]

Famous last words "we are never going to get near it"
NEVER HAPPENS if it is there someone will come up with some additional use for it

Sharyn

Well, we know when, how, and why we'll need to get near it. "Never" was hyperbole to mean, "I don't want to get into a debate on why I'm hanging a dead-hung pipe and not spending an extra $40k on a hoist mechanism for what will already be a $30k project." We fully intend on hanging some S4 PAR's or fresnels up there, but only running the lamps during concerts that require the bright, no-color wash. Then we'll have LED's for all other lighting on that part of the stage (the apron downstage of the proscenium arch).

Getting up there with scaffolding is easy. Getting up there with a scissor lift is less easy, but possible. Still trying to work out purchasing a vertical mast Genie lift which would be perfect for this application, but presently we only own a couple sets of scaffolding and two scissor lifts that are too heavy to drive on our orchestra pit fillers.

Without getting into the messy details; I had every possible option in the book priced out before we came to this.

 

[jglodeklights]

One recommendation I will make is- leaving some spare circuits (terminated to power or not) up there, whatever the decision is regarding rigging. SOMEONE, will want to put additional lights there. Running and leaving cable is easier than having to always re-run it.

My advice, again, save the 5 Grand. I don't think you are crazy for not wanting to having a moving pipe, especially one of that length. While it is convenient, Good LED units, properly focused, will be able to replicate many colors commonly used for down washes, side washes, etc, especially combined with some conventional units.

 

[MPowers]

We use All-Thread (threaded rod) for many installs. It saves a lot on the install time and labor costs. It is not right for every installation but is very good for the right installations. For over head rigging where rigidity is desired, pipe grids, display lighting, etc., it is a winner. Make sure the rod is grade 5 or better and all the components are the same. Eyes, turnbuckles et. al. drop forged, etc ad infinitum. My preferred pipe connection method is a two piece batten clamp

H&H Model 680 Batten Clamp
Formed of 10 gauge steel for snug attachment to 1-1/2" Sch. 40 pipe battens.
Two-piece assembly is attached using 3/8" Grade 5 bolts. Top hole is
sized for installation of thimble, turnbuckle, or shackle. Working load limit of
1400 pounds based upon straight pull

coupled to a H&H 448 rod suspension hanger http://www.hhspecialties.com/CAT16 2011.pdf page 55.

I do make one difference between the picture and my installs, I always double nut the lowest and highest connections, the actual weight bearing ones.

 

[beachbum]

We have 2 spaces--600 seat proscenium and 300 seat platformed space. The big house has 50' battens dead hung on steel cable with chain tails, the smaller space 48' battens on threaded rod. Both do the job just fine. Both spaces have woven cable skydeck grids also hung with threaded rod. The only real difference for us is that in the larger space, the grid(at 28' )is above the battens and cable connection allows us to change heights. In the other space the grid is at 14' with the pipes above it so immobility is not an issue. If you are not planning height changes, or do not allow them, the lower price seems a good bet, all safety concerns being equal

 

[egilson1]

Another thing to consider is how long the lift line/rod is. With long threaded rod you don't want to be shifting the CG to far from under it, as the rod will "bow" and will de-rate it.

Ethan
ETCP certified rigger
Arena & Theatre