Strength of tieline?

[gafftaper]

Originally Posted by photoatdv

I thought tie line was rated to 500lbs? Am I wrong? Though I did see several pieces snap clean through when some genious decided to fly out the projection screens on my last show. That was a real mess (the screens only weighted about 20lbs, but they didn't fit between the battens on the sides of them.).

I just want to clarify that we are joking about the use of Tie Line in rigging. I got a PM from Photoadv and apparently he had two "professionals" tell him it is acceptable to use tie line for rigging because it has a test strength of 500lbs. So he was asking a serious question above. Let's be really clear here... It IS NOT acceptable to use tie line for any form of rigging. These "professionals" who told photoatdv it's safe ARE WRONG and I would be concerned for my own safety working in their theater.

While I must admit that my love of tie line is nearly as strong as my love of Gafftape let's be very clear...
It doesn't matter how strong the test strength of tie line, rope, chain, or any other material is. The question is, is it rated for overhead lifting? The answer to most of those things is No. Even in super high strength chain there are many types that are not approved for overhead lifting. We are in that gray area where the answer to many questions is, "If you have to ask the question, don't do it find a qualified rigger." Unfortunatley many people just go to home depot and find some cheap Chinese chain and quicklinks rated at 500lbs and figure it will be safe to hang a batten. It IS NOT safe and you need to educate yourself more before doing any rigging.

The only acceptable ways I can think of to use tie line over head is to secure a cable to a batten or to secure a drop/curtain to a batten (and there better be a proper tie grommet at least every 12 inches on that drop or it's no good).

Now standby for a fabulous rant from WhatRigger? on the stupidity of using tie line for real rigging...

[JD]

Umm.. It is worth mentioning that there is a big difference between the term "Tensile Strength", the point at which something breaks, and "working load" which indicates the normal stress area that is acceptable. What was said above is correct, much like scaffold planks, the object in question needs to be rated for its usage, which includes the ramifications of failure.

Rigging and Electrical are two fields we do not discuss here. It has been said before:
"If at first you don't succeed, don't become a rigger!" There is no room for error in either field.

[derekleffew]

Originally Posted by JD

...there is a big difference between the term "Tinsel Strength", ...

Yes, JD. "Tinsel Strength" is how strong the silver ribbons are that one outs on Xmas trees. "Tensile Strength" is the breaking point. SWL, (Safe Working Load) is Tensile Strength divided by the safety factor, usually 5:1 or 10:1, depending on the application.

It is possible to buy #4 (0.125") Black BRAIDED POLYESTER CORD, with a stated SWL, but the stuff should not be called tieline. It's almost as expensive, but not nearly as strong, as 1/8" aircraft cable. By the time the efficiency of the knots used are factored, load limit is severely minimized. Due to it's vulnerability to heat (fire) should not be used for overhead suspension.

The only time I've used it was when working with a company called Transformit (cool website--nice pictures). [Rose Brand offers a similar product. Buying the raw fabric makes for an inexpensive set.] It was supporting ten pounds of spandex, maximum. Hey, where'd that "wedding guy" go? This would be good for him.

[derekleffew]

Posts above "pruned" from "Truss on Crank Lifts" thread.

[gafftapegreenia]

The following is a true story, shared from my experiences. Do not lecture me, it was not my fault.

Junior year in high school we had, as usual, dozens of muslin coverd flats to hang. Hey, highschool was old skool like that. Anyway, the rigger/local tech we had hired to help us with load-in/lighting focus assured me and my TD that it was fine to hang a row of 8 flats with tie line.

Despite me voicing my conerns, we did it anyway. WE GOT LUCKY. The next day we came in, and nothing had fallen, but half of the line has had their outer braided jacket snap, and the flats were hanging from at precarious angle from the inner core of the tie line. Let that be a lesson.

In addition, the next year I made the school buy D-ring plats and hanging irons so they would stop using eye hooks screwed into the top 1x4 pieces of the flats.

[gafftaper]

Originally Posted by gafftapegreenia

In addition, the next year I made the school buy D-ring plats and hanging irons so they would stop using eye hooks screwed into the top 1x4 pieces of the flats.

Oh you bring up another VERY dangerous bit of "rigging" that is VERY common in high schools. Kids, eye hooks screwed into the top of a flat are NOT a safe way to hang them. What happens if the wood splits? Think about all that weight you have depending on the tiny little threads of those screws. Tell your teacher they are wrong and it's not safe. If they don't believe you, send an e-mail to myself( or any of the usual suspects around CB) for a stern lecture as to why it isn't safe.

Perhaps we need a wiki/colaborative article on Unsafe rigging practices. As long as we are only telling people what not to do would that be ok with the TOS?

[gafftapegreenia]

I think that was the most unsafe thing we ever did regularly in highschool. I know our sets were usually overbuilt/securely braced.

[derekleffew]

Originally Posted by gafftapegreenia

...dozens of muslim covered flats to hang...

And I suppose you hung the blacks, too?

[gafftapegreenia]

Can I blame Freud on that one?

[gafftaper]

Hey Gaffbrother, Do you Dutch your Muslims?