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Fly System Safety Concerns

Discussion in 'Stage Management and Facility Operations' started by Jeremiah, Sep 23, 2011.

  1. Jeremiah

    Jeremiah Member

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    Hey guys. So I just recently graduated from undergrad and was fortunate enough to get hired on at a small college as a technical director. I was hired by the previous TD who was promoted to dept head. (Don't ask how that happened, I'm still confused by it). That being said, I was recently told by the previous TD aka my current boss that we need to re-rope all of the existing line sets on the FLY. Keep in mind that this Fly system (counterweight) is older than God, and hasn't been inspected in at least 20 years. So naturally I agree that yes, the lines should be replaced. Then he tells me that he and I are going to be the ones replacing them...... Now, this is where I'm a little unsure. Correct me if I'm wrong but I have always been under the impression that you had to get a certified rigger to do maintenance on a fly system?

    I just really don't want to kill any one....
     
  2. Sony

    Sony Active Member

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    Up until a few years ago with the beginning of the ETCP program there was no such thing as a "certified" theatre rigger for the most part, and there are still MANY people who are highly qualified riggers who do not have their certification. Your boss may very well be one of them! We don't know! There is no requirement by law for a person doing maintenance on a fly system to be "certified" in anything, but it is HIGHLY recommended. There is a big difference between certified and qualified, someone who is qualified to do the work may not be certified, but someone who is certified to do the work should be qualified, that's the theory anyways. A certification is literally just a piece of paper that states that by some form of agreed upon standards, whether it be a test, classroom time, on site training...etc, that YOU the person who's name is on the paper is "qualified" to do the work which you are doing. Basically it just gives you the ability to confirm that you are capable of doing the work that you say you are capable of doing in a form other than word of mouth.

    That being said, the hope if your boss does know what he is doing, changing out the lines on a fly system is NOT a task that is simple nor easy. However if he knows what he is doing then there is no issue with you guys doing it yourselves, just be safe, take your time and double check everything. If for one second he doesn't seem to know what he is doing or you feel like he is "just winging it" RUN LIKE HELL! and tell your school administration about his unsafe practices and beg for them to get someone certified in there to do it.
     
  3. Footer

    Footer Senior Team Senior Team Premium Member

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    Easy there, I would not go running to the admin that this guy is an idiot even if he is an idiot (and I'm not saying he is, this project it totally doable be most good stagehands). Its not really that big of a project... and if you can tie a few knots and know system operation it can be done pretty easily. Each arbor should be brought in (pipe grided), a few extra bricks should be thrown on to hold the arbor in, old purchase line is removed, new line is placed, floor block is floating correctly (most important part), both ends are correctly secured to the arbor, check lock tention, and repeat. If your a double purchase house it can be a bit more of a pain, but its also doable.
     
  4. MPowers

    MPowers Well-Known Member

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    Jeremiah,

    Of all the jobs that need being done on a fly system, replacing a purchase line is probably the least dangerous, least critical item there. This is one of the few things I feel I can give instructions over the net and not be out of line. Here is a step by step mini instruction.

    1. Remove as much weight from the batten as practical. Curtains, Track, raceways etc. can be left on. Strike as much lighting as possible and all scenery.
    2. Balance the lineset and move the arbor to an easy working position from either the locking rail (preferred) or a loading gallery.
    3. If the arbor is at low trim and sitting on the lower bump rail, put an extra 100lbs of weight on.
    4. Now secure the arbor, use a 5/16" minimum, proof coil chain and forged shackles to chain the arbor to the locking rail or loading rail in such a way that it cannot move up or down.
    5. Set up the spool of new rope on a pipe held up by stands or saw horses so that the spool can reel off the rope smoothly. DO NOT set the spool on end and feed the rope over the end of the spool.
    6. Remove the rope from the top of the arbor, cut off the old knot and all tape residue etc. If you already know how to make a long splice in three strand rope, splice the end of the new rope to the cut end of the old rope.

    Mini splice lesson. take the three strands of the rope, e-tape the end of each. unwind one strand about 24" and cut off. Unwind second strand about 12" and cut off. Do the same with the end of the new rope. Now take the two long strands left and wind them into the grooves left by the strands cut from the other rope. The two pieces cut at 12" should just meet in the middle. Trim the strands as needed to make sure they just meet and do not overlap. A little e-tape at the three spots where the strands end. This does not have to be a great splice, just has to hold the weight of the rope and a little pull. End result should be a splice that is the same diameter of the rope everywhere, with no loose ends, strands or e-tape hanging off.

    7. gently pull the old rope from the bottom of the arbor until the new rope arrives.
    8. Cut the new rope with about 36" for knot tying at both ends. (this can be reduced after you tie the first couple and find out just how much rope your knot tying takes up.)
    9. Tie to the top of the arbor. I prefer a Bowline at the top but a double half-hitch back to back is also acceptable if snugged tightly.
    10. Pull the rope through the bottom eye (or attachment bolt) of the arbor. make sure the tension block is at the top of it's travel. Have someone pull down on the back line as hard as they can, while the second person pulls up hard on the line through the arbor and starts the knot. I strongly prefer a double half-hitch back to back for the lower knot.
    11. pull the knots tight, snug them down. Trim the tails to about 4" past the knot (e-tape the rope to about an inch on each side of the mark, then cut in the middle of the tape.). Now finish by e-taping the tail to the standing part of the rope.
    12. Repeat 1-11 as needed.
     
  5. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Hey Michael,

    Is there a particularly reason why one would choose to use a bowline etc for the top knot rather than an eye splice? Time and ability to replace later are probably the reason, but as they say about curiosity and cats...
     
  6. Jeremiah

    Jeremiah Member

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    Thanks for all the info guys, It was greatly needed. I think I'm still going to try and get the rig inspected before we make an attempt to re-rope everything, just for safety sake.
     
  7. Sony

    Sony Active Member

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    Sorry! My brain was still waking up, I thought they were replacing lift lines, not purchase lines. >.< My fault! Replacing Purchase Lines is easy as pie!
     
  8. MPowers

    MPowers Well-Known Member

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    There are several reasons for a knot rather than an eye splice. The first is practicality. What do you gain/lose by using an eye splice?

    1. Strength: An Eye splice, properly done by an expert, will exceed 90% of the rope strength. A bowline knot will achieve about 45% of the rope strength. Do you need the total rope strength? The most common purchase line rope, 3/4" Multi line II has a WLL of about 1,500 lbs. In a Counter weight system, the linesets are designed to be balanced within about 50 pounds except when loading or unloading. Even during loading and unloading, with arbors tied off and secured, any out-of-balance situation should not exceed 100 pounds. Standard rope locks are designed for a 50 pound out of balance loading. There are rope locks designed for greater load imbalance but my personal opinion is that the greater capacity rope locks encourage poor rigging practice such as resulted in catastrophic run-a-ways like at the Galliger in Cedar Falls, Iowa, --- over a $1,000,000 damage to the stage and the equipment of the Blue Man Group. However we know that in practice, weight imbalances are often ignored during Ins and Outs to speed up the work. I have investigated 3 run-a-way arbor rigging accidents in the last 6 months, all due to severely out of balance linesets in the effort to speed up turn-overs.
    Even then the most severely out of balance line set was 900 lbs on a system using 1" Multiline II which has a WLL of almost 2,700 lbs. So, in all cases, even the 45% de-rating of the bowline is well above the out of balance situations. I.E. the strength of the eye splice is not needed.

    2. Cost. A Good, Reliable, well done bowline knot can be tied by any journeyman rigger in about 30 seconds. A good reliable eye splice can be done only by a skilled rigger in about 10 minutes. A knot @ $25 an hour, costs about 20 cents. An eye splice @ $75 an hour costs about $12.50. Times 30 linesets that is $6 vs $375.

    3. Time. 30 knots = 15 minutes, 30 splices = 6 hours. This can add an extra day in crew lodging, and expenses on a job.

    So the reason for a knot is:
    No strength advantage gained or needed.
    Considerable savings in end user cost.

    All that said, would I "like" to be able to put an eye splice and quoit (thimble) at the top? Well of course, If I were the owner, had a summer to do the labor myself, if it were a historical reconstruction, if I were Bill Gates.

    Bottom line, except for esthetics, there is nothing gained by the use of an eye splice.

    Hope this answers your question.--

    -
     
    Last edited: Sep 24, 2011
    RonHebbard likes this.
  9. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    So may I surmise that you're not a fan of a specific rope lock incorporating a deadman foot pedal made (still made?) in a small northern Ohio town? For the record, having tolerated one for two years, neither am I. The rest of their offerings used to be (no experience with them in the past ~25 years) top of the line; just not happy with that particular product, and its expense and operational "quirks".
     
  10. MPowers

    MPowers Well-Known Member

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    Not a fan. Also not a fan of the one manufactured to compete by a 120 year old rigging company.

    IMHO they, the locking or high capacity rope locks, lead people to rely/trust the lock and not take additional precautions such as snubbing, tying off, etc., and loading/unloading weight at the same time and same rate as the batten load. When the person moves on to a system with more conventional or "standard" rope locks, the bad habits are already learned and can lead to "incidents".
     
    RonHebbard likes this.
  11. Ianboze

    Ianboze Member

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    this input might come as too little too late but I feel for the good of the thread some additional information was needed.

    in terms of replacement intervals for handlines, it depends. different manufacturers will recommend different replacement intervals. New England Rope usually recommends 10 years. that being said replacement depends on condition of the rope. what is the diameter of the rope (how much has it stretched) , are there spots where the polypropylene core is coming out, does it smell funny (for natural fiber rope)? I recommend annual inspections with tracking and just replacing 4-6 per year. small expenditures yearly is much better than rushing mid-season to replace lines so you have operating linesets.

    in terms of replacement it is a simple task, splice the ends and pull it through. what to remember is that a fiber rope just as wire rope has a bend tendency from being spooled up and when unspooling you what to make sure that the natural bend of the rope will be in the same direction installed as it was on the spool.

    as for knots I recommend using hitches as apposed to knots. using two half hitches with a safety knot retains 75% of the breaking strength where as a bowline is in the neighborhood of 50%. also, I find half hitches easier to tie when tying a line in tension.
     
  12. DuckJordan

    DuckJordan Well-Known Member

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    Doesnt matter
    I would caution not to do two halfs and go with manufacture suggestion. Two half hitched I've seen come apart after a week of heavy use in a road house.
     
  13. Chris15

    Chris15 CBMod CB Mods Premium Member

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    And if you are using anything near those percentages of the breaking strength of the purchase line, you have a heavily out of balance lineset and that's normally bad news...
     
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  14. MPowers

    MPowers Well-Known Member

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    As Chris said, if you are worrying about the efficiency % of a knot in your purchase line, you are subjecting it to a far greater load than a normal counterweight system is designed to handle. The normal load on any CW system purchase line while in use, should never be more than 50 lbs in a static condition as that is what a "standard" rope lock (and the Thern Brickhouse lock) are designed to hold. Yes, there are two rope locks on the market which advertise the capability of holding a 1,500# out of balance load, but obviously no stage hand can move or safely handle such a load. IMHO those "super" locks foster poor loading and unloading practice and can lead to improper training and possible accidents when technicians move onto other systems with standard locks. Please read my reasoning in posts 8-10 in this thread. Be aware that we choose the purchase line size we do as a function of the size of the rope and the size of the average human hand (adult male), not because of a need for a certain load capacity. Purchase lines range in diameter from 5/8" to 1" with the vast majority being 3/4". This size is large enough to grip comfortably and grasp firmly for heavy or fast movement. A 3/8" diameter rope with a ultimate breaking strength of 3800# would handle our loads, but would be too small to comfortably grip at any load, so a larger line is preferred. Just FYI here is an excerpt from a New England Rope strength table for the sizes we most often use. Note that the common 3/4" line has a 13K # breaking strength.

    Size.......Weight lbs/100'...........Tensile lbs
    5/8" .........10.4..........................9,800
    3/4"..........14.5 ........................13,300
    7/8"..........17.9 ........................15,200
    1"..............21.1........................19,100

    In Reply to DuckJordan, If you experienced a knot or hitch that
    the knots/hitches were improperly tied, not snugged down, dead end not whipped or seized to the standing line or all of the above. Any properly tied and whipped termination should last the life of the rope. An arbor termination hitch that comes undone in a week under any use, could not have been correctly applied. There are knots that are designed to easily come undone when tension is released but these should not be used for counterweight arbor tie off.
     
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  15. ruinexplorer

    ruinexplorer Minion CB Mods Premium Member Fight Leukemia

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    I think I need some brushing up on some rigging knowledge after reading this. Admittedly, I haven't had to be a rigger in several years. My memory was telling me that a traditional bowline (tail ends up on inside of loop) was up to 65% strength while the cowboy or Dutch bowline (tail ends up outside of loop) was the one with around of 50% strength. The reason for this was how the knot put a different bend on the standing part of the line (though I don't know of an actual strength test like Delbert Hall does with other components). I did find a good blog with talks about the components of what goes into knots to help understand why they have different degrees of strength.
     
  16. cmckeeman

    cmckeeman Active Member

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    i have read that a bowline is anywhere from 50 to 60, i think the figure 8 is rated at 85, clove is 75. it would be interesting to do my own experiments.
     
  17. Eric J Carney

    Eric J Carney New Member

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    Good information here. Your rope manufacturer should provide info on how to secure loads as per its spec. I just completed a job changing out operating lines using the splice method to feed new line through. Make your terminations as smoothly as possible and don't be afraid to make a slip knot by putting two overhand loops in a line and putting the lower loop through the upper loop and then pulling down. When it gets stuck at the loft block step in the slip knot carefully and put some weight on it to make the bulky bit come through. If your splice is good you'll succeed. There is really no need to unload pipes during this process. Make a prusik loop by tying two fisherman's knots and tightening them on each other. Fasten your prusik loop with a prusik to the line you would normally use to fly a pipe in. Fasten a rachet strap with hooks to both the prusik loop and an appropriate place on the fly rail. Then shackle an appropriately sized span set or gak flex thats choked around a secure point to a fixed place on the arbor, hopefully an eye-bolt that's there for that purpose. Choose the right piece of span set, gak flex, or webbing so your knot can be tied at an appropriate height. Don't forget to block up the idler with a spring clamp or other method. A good crow bar should help you to lift the idler so your partner can get a block or clamp in there. Ratcheting down will immobilize the line set and you'll be free to tie off with the added benefit of the slack being pulled out of the operating line. Remember the counterweight system is in equilibrium with or without the operating line. That line is for the sole purpose of us interacting with it. Make sure you're in equilibrium before you mess with anything. Make sure everything is immobilized WITHOUT THE BREAK. Tighten your rigging carefully as you release the break. If you can move the line set after every things tight and the breaks off something isn't right. Be safe, communicate and watch the pinch points. Good Luck.
     
  18. Eric J Carney

    Eric J Carney New Member

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    Apologies. This is the method I used to tighten the Arbor side of the hand line after the line stretched in after they had been replaced. During the initial replacement the arbor was immobilized in a similar fashion... just not to the operating line.
     

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