Welcome to netHEADS!
The Occasional When-we-feel-like-it Email Newsletter from Sapsis Rigging, Inc.
004 May 29, 2000
Contents:
Memo From Uncle Bill: Counterweight Arbors
Introducing Mike Yocum
On the Road with Uncle Bill
GreenGoods - Earth Day Specials
Babyland
A Sapsis Enviro-Tip
With Tongue in Cheek
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Greeting campers, and welcome to another edition of Heads! online.
It's mid-spring already. The seasons are just whizzing by. Let me get this article finished so I can go outside and play.
The topic for today's epistle is counterweight arbors. I know I talked about counterweight equipment in the last issue (See Uncle Bill Talks About... Rope Locks) and you may think I'm in a bit of a rut, but I'm not going to stop writing about counterweight gear until people start using the equipment properly and stop hurting themselves. Fair enough?
Counterweight arbors ("cradles" to our good friends in the UK) are a relatively simple, but essential element of a manual rigging system. A counterweight arbor is a metal frame that rides in a guide track. It is where you put the steel weights (the counterweights) that balance out the load when you put something on the pipe (also called a batten.)
The three most important things to know when working with counterweight arbors are:
1) when to load weight into the arbor
2) how to keep the weights in the arbor
3) when to take the weights out.
Lets start off with getting the weights into the arbor.
Just for giggles, let's assume you've just started loading a production of Kiss Me Kate into your local high school theatre which is equipped with a full counterweight rigging system, including a grid and loading bridge. The first thing you'll want to do is hang the onstage lighting. So you bring down the battens that have been designated for lighting. Lowering these battens causes the counterweight arbors to raise to the loading bridge. Next, get out your lighting plot, the lights and lots of minions (crewpeople). Send two minions to the loading bridge and keep the rest onstage to hang the lights. Once you have all the lights, hardware, cable, etc. on a batten, calculate (notice I didn't say "guess") how much the pipe and all the gear weigh. (Take off your shoes and use your toes if you have to.) When you know that amount, call up to the nice minions waiting patiently (i.e.: napping) on the loading bridge and ask them to load counterweight into the arbor. If you have a single purchase counterweight system you'll load an amount equal to the weight on the batten. If you have a double purchase system, then the nice minions will have to load twice the weight on the batten. (They may not like hearing this part, but there's nothing you can do about it. That's the way a double purchase system works.) When the loading is done, you should have a reasonably balanced counterweight set that can be raised or lowered by one person.
To unload the arbor when you are taking the show out, you simply reverse the process. Bring the batten to the deck but don't take the lights or scenery off. Not yet. Remove the weights from the arbor first, then take off the weights. And remember the batten also has weight. You will need to leave a few counterweights in the arbor to balance out the empty batten.
Now, let's chat about keeping those weights where they belong. There are two key pieces of hardware that help prevent the weights from coming out of an arbor.
The first are spreader plates. These are steel plates about 2" wide and roughly 14' long with 2 holes in them; one hole for each of the 3/4" Ø arbor rods. These plates slide up and down those rods. Their sole purpose in life is to prevent the arbor rods from bending in the event of an out-of-balance accident. Whoa! Hold on for a sec. What's an out-of-balance accident, you ask? Well, I'll tell you.
An out-of-balance accident is when the weight in the arbor is greater than the weight in the pipe, or vice versa. It happens when too much weight is put into the arbor, when the weights are put into the wrong arbor (hey, it happens) or when the scenery is removed too soon from the pipe. When one of these scenarios occurs, the heavier side of the system (either the batten or the arbor depending on the problem) can come crashing down to the floor or go screaming up to the grid. Need a visualization? OK...
You are the deck chief. You just loaded 500 pounds of lights onto set #10 and have now asked the crew on the bridge to load 500 pounds of counterweight into the arbor for set #10. But the loading crew gets confused and loads 500 pounds into the arbor for set #11. There is nothing on the batten for set #11 to balance this new weight. At some point the rope lock for set #11 gives up and lets the rope run through. This allows the arbor to come crashing to the floor and the pipe to go crashing into the grid.
OK? Got the picture?
So, about those spreader plates. They are designed to keep the arbor rods from bending. Without the plates, the force of the collision of the arbor against the bottom stop, combined with the weights crashing around, could turn the 3/4" steel rods to spaghetti. With the rods all twisted, the weights could easily fall or be forced out the sides of the arbor. This is a bad thing. Weights bouncing around the stage are a definite no-no. The plates hold the rods by being placed into the counterweight stack properly. There should be no more than 2'-6" between plates in the arbor. So just before the loaders on the bridge start putting weights into the arbor, they have to lift these plates up to the top of the arbor and tie them there out of the way. Then they start putting weights in. When the weight stack gets to be 2'-6" high , they allow one of the plates to drop down on top of the weights. Then they continue putting weights into the arbor. (Yes, right on top of that first plate). When they get another 2'-6" of weights in, they let another plate come down on top of the stack. See how this works? The plates are stuck there in the stack and they hold the rods together.
The other extremely important items in the arbor are the weight hold-down collars. These collars are steel tubes that ride up and down the arbor rods. There's one on each rod. They have a threaded hole in them with a thumbscrew inserted into the threads. These collars exist to prevent weights from being forced off the top of the stack when the arbor crashes into the top stop. How could that happen? Well...
Maybe the deck chief didn't calculate properly and there's not enough weight
in the arbor to balance the load. But there is enough to allow two people to
pull the arbor down, which they do. So the pipe is pulled out to trim and locked
off. An hour later, the master electrician needs to bring that pipe in because
there's a dead lamp he/she needs to replace, but doesn't know about the out-of-weight
condition. The rope lock is opened. The pipe starts moving by itself because
it is heavier than the arbor. The master electrician says a bad word. The pipe
starts coming down faster and faster until the arbor crashes in to the top stop
bar. The force of the crash is
more than enough to knock a weight or two off the top of the stack. That's where
the collars come in. They're supposed to be on top of the very top weight with
the thumbscrews tightened against the arbor rods. That's what keeps those weights
from flying off. The thumbscrews need only be finger tight to do their job.
If the arbor hits the top stop and the collars aren't tightened down, or not
there at all, then a weight is going to come off that stack. And if you thought
a weight falling out the side of the arbor 2 - 3 feet off the ground was a bad
idea, a weight falling from grid height can be absolutely lethal. The weight
hold-down collars must be tightened down at all times. The loaders are not finished
their job until those collars are in place.
And that, as they say, is that. Using the spreader plates and weight hold-down collars properly will not prevent runaway arbors. But they will certainly help minimize the damage and possible injuries caused by one of those accidents.
OK, enough of my prattle. I'm going out and walk the dog. We both could use the exercise.
See ya in the funny papers.
Be Well
Bill
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Visit the Uncle Bill Archives at
http://www.sapsis-rigging.com//UB.ArticleIndex.html and catch up on those
veritable pearls o' wisdom from our favorite rigging master.
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Welcome to Mike Yocum
Mike joins Sapsis Rigging as our new Production Manager. Mike moved here
from Boston with his wife and brand new baby . We are currently considering
possible nicknames for him so as to alleviate the confusion caused by having
more than one Mike in the shop. When we come up with a suitable moniker you
can be sure we'll keep you posted.
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On the Road with Uncle Bill
Our own Bill Sapsis has been on the road dispensing his words of wisdom to
several lucky groups of technicians. Recently he spoke to the good folks at
The Way International in New Knoxville Ohio and to the technicians at IATSE
Local 133 in Stamford CT. At the end of May Bill and associate David Hearn
will be conducting a week-long rigging seminar in Tampere Finland for
Teatterikorkeakoulu - The Theatre Academy of Finland. In June he will be
paying a visit to QVC in West Chester PA. And he just scheduled a seminar
right in our own backyard at the Keswick Theatre in Glenside PA.
Go to http://www.sapsis-rigging.com/seminars.html for more information about
the Sapsis Rigging Seminar program.
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BABYLAND!
Our friends Kevin Pitcock of Peak Trading and Dee Dee Pitcock
are the proud
new parents of Sophia Pitcock born
May 9, 2000 6:45 pm
Just about 7 lbs and 19" long
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From Chris & Heidi Sprague:
Hello! and Happy Holidays! I just wanted to share our good news with everyone!
The little one decided to show up right in between the two holidays, because
there's not enough happening between the end of Dec. and the beginning of January!
Trentin Christopher Sprague 8 lbs 7 oz
21 -1/2 inches long
Born at 5:30 PM on Tuesday the 28th of December
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From Helen Willard:
Eli Charles Peterson Wood
Born April 24, 2000
9lbs. 7ozs. 22" long.
Joins brother Ryan James Peterson Wood, 20 months. The proud parents are Jennifer
& Terry Wood -- Jenn is my sister.
This news may be a bit stale, but another of my sisters had twins in October
-- Collin Matthew and Meganne Kathryn were born October 14, 1999 -- joining
brother Luke Peterson Brenon, now 2 and 1/2 years. Their proud parents are Anne
& Matt Brenon.
Uncle Frank & Aunt Helen are delighted to be major spoilers of their niece
and nephews.
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A SAPSIS ENVIRO-TIP
Celebrating our favorite natural house-hold product, Baking Soda. It's inexpensive,
it's versatile and it's non-toxic. For more uses than you ever imagined check
out The Baking Soda Page.
http://frugalliving.about.com/parenting/frugalliving/library/blbakingsoda.htm
For some cheap thrills try making your own Baking Soda Bubble Bomb
http://www.exploratorium.edu/science_explorer/bubblebomb.html
Is any one out there using baking soda in their shop? We'd love to hearabout
industrial applications and creative uses as well. We'll publish ourfavorite
responses in our next HEADS! newsletter.
Write us at netHEADS@sapsis-rigging.com
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With Tongue in Cheek
We apologize for for the unseemly length of time between issues, but we at Sapsis
Rigging have been straight-out in our preemptive corporate organization planning
sessions. In an attempt to delay the Justice Department from arbitrarily splitting
SRI "in order to prevent future monopolistic practices", we are currently
considering the following divisions of our corporate entity:
SRI Synthetics Division - all Polyester and Dacron based ropes, roundslings,
and webbing based goods.
SRI Natural- manila and tweezers
Sapsis Rigging Stage Right
Sapsis Rigging Stage Left
Sapsis Lite: One rigger with a Leatherman
The We're not Sarris' Candies or Quality Foods, but Their Phone Numbers are
Just One Digit Different than Ours and We'll Be Happy to Give Them to You in
Spanish or English Division
SRI Popular Services - Those gigs that save a client's butt at the last minute.
Why walk on water when you can drive a Rolls over a swimming pool?
SRI Secret Services - The jobs we don't admit to knowing how to do, but at least
twice a year find ourselves doing as a favor to a client; like those gilded
PVC Gold-Leafed Palm Trees.
The Sapsis Halloween Department: No we don't have fog machines, bubble machines
or anything we would let you "hang" someone with, but we do have a
kind of scary looking guy who sometimes freelances in New York.
Uncle Bill's Road Show - Come on, don't you think it's time he had his own corporate
logo?
The We Don't Fly People, (Not even just a little bit; not straight up and down
again and not a few inches off the floor) But We Know Who Does Referral Service
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Copyright 2000 Sapsis Rigging, Inc.
http://www.sapsis-rigging.com
233 N. Lansdowne Ave. Lansdowne, PA 19050
800/727-7471 FAX: 215/228-1786
