"Sunken Arbor Well"....or Basement Bricks How Come?

tdtastic

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Sep 16, 2014
Location
Alabama
Random question:
I was on a site tour of a new facility the other day that's still in the concrete-pouring phase, but when looking at the stage house I was told they are preparing for a rigging system that will allow the arbors to pass below stage level into a basement pit.

I've only ever seen this before in another very large heavily-used space. Why is this done? Is it really just to allow the battens to lower all the way to the floor?

I can see how allowing the arbor to travel sub-level would help overcome the loss of batten travel due to height of the floor block and the arbor itself.

Is that really the big advantage? Would love some input on the benefits of this rigging feature.
 

JAC

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Jan 10, 2018
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Cleveland
You bet, if you ever worked anyplace that had this feature you would curse every place you worked that didn't.
 

RonHebbard

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Location
Waterdown, ON, CA
Random question:
I was on a site tour of a new facility the other day that's still in the concrete-pouring phase, but when looking at the stage house I was told they are preparing for a rigging system that will allow the arbors to pass below stage level into a basement pit.

I've only ever seen this before in another very large heavily-used space. Why is this done? Is it really just to allow the battens to lower all the way to the floor?

I can see how allowing the arbor to travel sub-level would help overcome the loss of batten travel due to height of the floor block and the arbor itself.

Is that really the big advantage? Would love some input on the benefits of this rigging feature.
@tdtastic Placing the idlers below deck level moves the noise of arbors hitting high travel / lower EOT (End of Travel) stops off stage and into a basement. If the system includes motorized bull winches, the motors, their drives, their RF, magnetic and mechanical noise are also moved to one, or more, levels below stage level. This also facilitates servicing and maintenance with less disruption of stage time.
Toodleoo!
Ron Hebbard.
 

RonHebbard

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Waterdown, ON, CA

SteveB

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Mar 20, 2004
Location
Brooklyn, NY
The limitation on travel of the pipe is driven by limitations of travel of the arbor.

Placing the arbor bottom blocks in the basement increases arbor travel, which increases pipe travel. One benefit is pipes that come to deck, where it’s easier to attach to flying scenery.
 
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BillConnerFASTC

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Jan 30, 2010
Location
Clayton NY 13624
I routinely plan arbor pits for the reason Steve points out. If there is a full grid, not as necessary but to get maximum travel to underhung blocks without a grid, the pit helps.

Just visualize the tall arbor and the batten habing no heigth. Skettch it.
 

Van

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Portland, Or.
I'm currently working on a project that does NOT have an arbor pit designed into it. As a result of this we are having to request that we install a significantly shorter Arbor in hopes of squeezing every last inch of travel out of the t-bar wall. Without the extra travel, afforded by the pit, you either cannot get a batten all the way out, or it's 8' off the deck when it's all the way in.
 

RonHebbard

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Waterdown, ON, CA
I'm currently working on a project that does NOT have an arbor pit designed into it. As a result of this we are having to request that we install a significantly shorter Arbor in hopes of squeezing every last inch of travel out of the t-bar wall. Without the extra travel, afforded by the pit, you either cannot get a batten all the way out, or it's 8' off the deck when it's all the way in.
@Van Have you considered double purchase? I realize the arbor needs to be at least twice as long but have you at least sketched it out?
Toodleoo!
Ron Hebbard.
 

Van

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BillConnerFASTC

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Location
Clayton NY 13624
Just for the record, I hate double purchase. Too much extra loading and unloading, 1/2 again as much friction, and much larger structure - head block beams and loading bridge. (Only bigger design blunder is no loading bridge!) Wider arbors and weights. And if stuck in a retro fit, I do long trim chains or similar so you can get the highest possible trim if needed - albeit tying that drop on from a low scaffold - or have the battens 405' from the floor.

High trim, travel, capacity - nearly first drawing I do is to make sure whats needed can be installed. If motors instead of manual, speed becomes the fourth fundamental. Those 3 or 4 factors determine a large majority of the structural framing.

And a rigging pit is always nice because it allows a lower loading bridge. I love it when the loading bridge is fully under the gridiron and you can walk to the head blocks. The pit also makes upright head blocks more feasible - which is a desirable option for install, service, and safety.

Too much caving in when planning these things. Its a tiny fraction of the total cost of the building to do it right.
 

egilson1

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Feb 25, 2009
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Boston, MA
But arbor pits stand in the way of my global plan to re-educate flyman in the proper use of tension blocks.

Ok, maybe not. But they do prohibit the already underutilized function of tension blocks. That being the ability to release the tension block in order to pull the “out” line onstage which in theory will help the flyman “put more muscle into it”.

Ethan
 

BillConnerFASTC

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Jan 30, 2010
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Clayton NY 13624
Well, yes. However Midwest Scenic at least more than once built a push rod the "stepped on" the Welsh block in the pit from the lock rail.

The fact is if it weren't for taking a bite on the hand line, the need for a floating block has gone away with synthetic rope. I have two projects with wide flanges half in the rigging pit floor and upright blocks clipped to them. Makes some forms of motorizing very simple. Floating tension blocks we're a response to manilla handlines significantly varying in length with humidity.
 

Robert Books

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Oct 22, 2014
(Only bigger design blunder is no loading bridge!)
my undergrad had the stairs up to, and platform for, the loading bridge, but no actual loading bridge. Some bean counter decided they didn't need all the extra steel and the cost of it. We were the largest theater in the area outside Boston, so had many touring shows in. Was fun watching the union guys bitch about preloading or hoisting uncountered lines.
 

TimMc

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Feb 15, 2017
my undergrad had the stairs up to, and platform for, the loading bridge, but no actual loading bridge. Some bean counter decided they didn't need all the extra steel and the cost of it. We were the largest theater in the area outside Boston, so had many touring shows in. Was fun watching the union guys bitch about preloading or hoisting uncountered lines.

Yeah, we bitch about preloading and hoisting uncountered lines because they're inherently unsafe. The "unsafety" can be mitigated to a certain extent but there is no way to make this "safe" in the minds of anyone outside of theatre. How much compensation is the venue owner willing to pay to the survivors of the deceased and for the disabilities created when the safety kludge fails?