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Safety Cables

Discussion in 'Question of the Day' started by ship, Jun 1, 2005.

  1. ship

    ship Senior Team Emeritus Premium Member

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    This is why you don't make Home Made safety cables unless other than of standard type.

    How many safety or liability problems can there be found with this "safety cable" I found today that came back from a show? (Someone else's gear and they won't be getting it back.)

    I'll start it off, it failed the Go/No Go gauge.



    Code:
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  2. Radman

    Radman Well-Known Member

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    Ahh I CAN find something wrong with this. There is not enough sticking out of the sleeves, and that bend around the clip is too tight.

    I'm slightly worried now because it appears that safety cables actually are that important and we don't use them much at all. Only where c-clamps aren't used. Plus we have a hanfull that look like that one, except slightly better (sometimes) in construction. Mostly this is due to the fact the I was taught that it's more likely that the pipe will fall than it is the clamp will fail. I sometimes will use a safety cable when moving lights and take them off, but generally we dont use them on pipes. I've never evenherad of a clamp failing. At least not one of the heavy duty c's!
     
  3. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Not familiar with this expression - care to explain?
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    The first answer if you look closely at the loop end you will see some of the wire rope ending at the end of the wire oval sleeve. The snap hook end is at the wrong angle to see if or if not it's the same. The wire rope should extend only to the edge of the sleeve. Less than this and it's not being crimped, more than this and while not a problem in holding, it will snag splinter etc. the users of the safety cable.

    You are correct however on the second part of the answer in minimum bending radius of 7x19 Galvanized Aircraft Cable.

    If you are not using C-Clamps, what are you using? In any case, the advent of the safety cable was because of C-Clamps failing. While these days they are much safer, the intent is still there because of them, much less for all other applications. All it takes is a gorilla with a 10" C-Wrench and you will note a very bent clamp. Once something that's cast is bent, it's no longer structural. No doubt it was more common for clamps in the past or from China to break rather than bend but once bent it has failed.
    Beyond this, given clamps are known to break, or not be clamped down sufficiently - forgot, or the screw provided in modern fixtures in my opinion are often too short, the safety cable is still very necessary for any fixture used overhead.

    I agree that I'm less seeing a Heavy Duty C-Clamp fail - either the 2" pipe Altman or the standard ETC clamp. The more old style normal Altman type clamps I see bent often. They more stip out or the 1/2-13 screw is loose to the point if only 1" long it could fall more so than them bending or breaking. On the other hand, it's necessary.

    Question beyond the 10" wrench is shock loading or what hits the fixture. Since it's cast material, it has a lot less resistance to impact than other bent forms.
     
  5. propmonkey

    propmonkey Well-Known Member

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    i wrap our saftey cables twice around and i make sure i have one on each, i cant fly the pipe up unless theres one on each, though if the instrumnet has a hook like a source 4 or parellipshperes i try to use 2, one around the yoke and one in the hook.
     
  6. ccfan213

    ccfan213 Active Member

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    I went to home depot once to see if i could just make safety cables and they told me that the handheld crimping tool they had was not powerful enough to be reaonably sure that it would hold. they told me that when safety cables are made they use a motorized crimping too. so my question to those of you who are making your own cables is, are you using a handheld tool or a power tool in crimping it?
     
  7. Lisa

    Lisa Member

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    It looks a little discolored/rusted on the right side - would that pose any sort of hazard?
     
  8. avkid

    avkid Not a New User Fight Leukemia

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    Nico-Press crimp tools are expensive, like about $90 US
     
  9. PATech

    PATech Member

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    We are rather religious about safetying our instruments. In the black box there is no need because if an instrument were to fall, it would be stopped by the tension wire grid.

    In the proscenium theatre, all of our underbalcony positions are rigged with Uni-strut. Unfortunately, there isn't really any way to safety cable those instruments, but everything over the stage and house that's mounted to a pipe has a safety cable.
     
  10. ship

    ship Senior Team Emeritus Premium Member

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    How about a 1/4" unistrut nut, 1/4" unistrut washer and drop forged shoulder eye bolt to safety to? Intent is to provide an alternative means of holding the fixture, doesn't mean you have to wrap around the conduit it's hung from.

    "It looks a little discolored/rusted on the right side - would that pose any sort of hazard?"

    Yes it would but in this case it's rubbed off gold paint. Who ever made these cables intended to keep them and used the paint to mark them as theirs. Now since there is no name on the gear it's just a question of tracking down who uses gold paint to say "hey, this stuff is ours."
     
  11. ship

    ship Senior Team Emeritus Premium Member

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    Good question, anyone care to explain?
     
  12. jonhirsh

    jonhirsh Active Member

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    Hey this is what i have never understood, why would you make your own saftey cables when you can buy one for 3-4 dollars at the most expensive fist of all when you buy it you have someone to blame if it fails that more then likely has insurance to cover the damage from there faulty product. and second how much money really could you save by making them your self realy lets say they cost 2 dollars insted of 3 in the large picture unless you need hundreds of them its probbaly cheeper to buy them not to mention the man power costs of making them.


    buy your safty chains.

    JH
     
  13. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Yep - I am with you on that one. From what I understand the savings on making them in bulk yourself are still not enough to make it worth it.

    Provided that you use them correctly and ensure they are rated for the item they will prevent from falling, then the liability if one fails will rest with the manufacturer.

    Can anyone remember what the rating specs are. 3x the weight of the item comes to mind but I am not sure if this is correct. i.e. if your can weighs 2kg then the minium breaking load of the safety chain needs to be 6kg (Based on the 1:3 ratio if in fact this is correct)
     
  14. soundman

    soundman Well-Known Member

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    GO/NO GO
    something I rememer from my rigging class. When is Compression sleeves (I think thats the real name and Nico press is a trade name) or a varity of other conectors it is important to check to make sure they are plenty tight. I GO/NO GO is simply a piece of metal or plastic with a bunch of groves or slots cut into it that you put the fitting in. If it fits it is a go, if it dosn't fit crimp again.

    ************cheating********************
    I pulled out my stage rigging handbook and it said to leave an 1/8 out side of the sleeve. I guess this is so at a quick glance you know that it crimps the whole thing.
    aren't there supposed to be 3 crimps and a copper sleeve or has that changed since printin.g of the book
     
  15. Radman

    Radman Well-Known Member

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    Uni-Strut, direct bolt, angle irons for smaller lights, plenty of options beyond Mr. C-clamp! Gaff tape, hot-glue...

    I see what you mean about the bent clamps. I am disappointed to say that half our clamps are twisted, stripped, bent or otherwise deformed in some way. I wish we could afford new ones. And more safety cables. I need to get a camera of my own, I've got so many "what's wrong with THIS?" items I'm stuck with using, the younger padawans would be learning nonstop!
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    John figured out the hard one. There is three more very important problems with the safety cable in question yet to go I noted about it. Should be fairly obvious.


    Good on the Go/No Go gauge, but if it failed the test, because you always close the tool until it locks, the crimp failing would indicate a tool that is out of adjustment. Very dangerous to fall into a false sense of security with these tools in thinking that just because it's crimped, it's safe. You will note in the tool manual also that the tools are supposed to be sent in for adjustment once a year. I'm more for verifying with the gauge each time it's used. There is also a different gauge for Stainless Steel verses other types of oval sleeve.

    Average pricing on the tool is more like in the $150.00 range for a good price.


    I will have put the manufacturered cable question like this:
    Does not use traceable elements. All rigging is required by liability to have traceable elements to it. In other words parts making it up that can be traced back to the manufacturer or supplier, this as a pre-made safety cable that's bought assembled should be able to be tracked back to the source.

    Since in this case it's "found safety cable", and cited above to be obviously home made, should there be a problem with it, it's use would make the user not the manufacturer liable. Much less since the parts of it used cannot be attributed to any specific manufacturer or supplier, the end user is very liable for this cable when it fails and this cable has a really good chance of failing. Had I made the cable in the case of an unstandard length it will have been a different story by necessity. Given of course it will have been made properly.

    Given a snap hook probably costs about $2.50 each, and say another $0.25 for the Nico Sleeves/ovals the best you could hope for would be breaking even on making it yourself verses buying a safety cable.
     
  17. SketchyCroftPpl

    SketchyCroftPpl Active Member

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    I don't know what its called off the top of my head but there isn't any protection on the wire loop to stope ware from the caribeaner thing from moving. I know thats not why it failed but it could have been another thing that could have done so later.

    ~Nick
     
  18. ship

    ship Senior Team Emeritus Premium Member

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    Did someone delete their post in having one part of the right answer? Yes it was correct in minimum bending radius. Re-post because you noted something that you should credit yourself for noting.


    The snap hook or as McMaster calls them "Load-Rated Snaps" has what's called a eye to it which is used to retain the wire rope loop. The snap hook is not the problem in this case thought they frequently will rust bend or fail.

    Frequently in rigging one will use a "thimble" to prevent the wire rope from bending beyond it's minimum bending radius. New Euro safety cables some day might become our standard in using at least a smaller "AN" type thimble. Always wondered about bending radius of the wire rope verses the snap hook dia. In any case, It's when a question of how tight that cable is wrapped around the snap hook correct in being a wee bit too tight in my opinion.

    Carabineer's are repelling D-shaped items for wrapping rope around.
    Snap hooks are similar in principle but are of other than D or augmented D shape and much smaller. Their intent is to do industrial latching but not much rated for overall load or repelling.

    While it's hopeful that you get to speak without having to do research into terms, unfortunately where the difference between safety items are concerned, giving the wrong term can be very dangerous. Much less in me posting say mcmaster.com # 3716t51 as common verses for example http://www.peaktrading.com/productpages/default.aspx?ProductPageId=1709 in even the website noting that it's not something you want to climb with unless you double up and reverse, yet similar to a snap hook.

    Similar concept and even latch mechanism, but should a aluminum carabeener be bent in an incorrect way, it won't function properly. Much less a aluminum carabeener won't get along well with galvanized aircraft cable.

    Neither is ideal, but the steel will hold up better and be more cost effective. In saying carabeener, one might think they can go to their local Sport Mart and buy what is acceptable for a safety cable snap hook - especially even settle on a key chain version.

    Thus the correct term is important. Just wait until you spend a few $K a day as a buyer. At such points if you use the wrong term, you get what you ask for - given even the sales staff is compitent.

    Don't know if it's any help in me and some others knowing what you mean in not meaning a carabeener but others would not. That's the intent.

    Still by my count three vey basic problems with this "safety cable."
     
  19. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    I think you are referring to the following post by Radman (first reply to your original question):

     
  20. propmonkey

    propmonkey Well-Known Member

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    are you sure thats homemade? most of ours look like that(40+) we have some homemade ones(dont use much) that have copper nico sleves. we just bought 10 new saftey cables i wish we had more of them.

    i was taught to do 3 crimps not 2. and the loop on the connector side looks to small.
     

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