James Posted March 16, 2005 Share Posted March 16, 2005 Please feel free to shoot this unquantified solution down in flames :unsure:<{POST_SNAPBACK}> OK then :) OK, I know that "bolts don't fail", <{POST_SNAPBACK}> You might believe that bolts don't fail, the existance of the guotes in your post indicates some scepticism but I have been standing under a lantern where the bolt failed in use and I was only saved because there was a safety. This particular failure may have been due to the bolt not being tightened up enough, there might not have been any shakeproof washers, it might not have been lock-nutted BUT this was a mechanical lighting effect that under its own motion caused the bolt to come undone. As it was I was only just missed by the falling bolt. James Link to comment Share on other sites More sharing options...
sam.henderson Posted March 16, 2005 Share Posted March 16, 2005 I would be a little bit dubious of attaching a safety chain to more than one lantern even on a stand! If a lantern did fail then it is going to start pulling down the other one and lets face it if a hookclamp is going to fail then its probably down to an incompetent person rigging it/ attaching the hookclamp that may mean the other lantern has been rigged to a similar calibre and with excess weight from the lantern dangling it could also come unattached. I agree with Lightnix that if you just put a sort of barrier on each end of the Stand that would stop failed lanterns sliding off!! Sam. Link to comment Share on other sites More sharing options...
TomLyall Posted March 17, 2005 Share Posted March 17, 2005 I have to disagree with the statement about secondary suspension always being a good idea, it is not as simple as that. One of the most important things to concider, is the shock loading which may result from a failed primary suspension. In this situation, it may result in the stand becoming unstable, which I would imagine may be a worse outcome. If you are going to safety something, leave as little 'slack' in the safety as possible. The less distance the fixture has to fall, the less shock load it will generate. Link to comment Share on other sites More sharing options...
Ekij Posted March 17, 2005 Share Posted March 17, 2005 One of the most important things to concider, is the shock loading which may result from a failed primary suspension. In this situation, it may result in the stand becoming unstable, which I would imagine may be a worse outcome.Would rope (including a piece of bungee-cord to reduce the shock load) be a good safety connection then? Link to comment Share on other sites More sharing options...
Andrew C Posted March 17, 2005 Share Posted March 17, 2005 Would rope (including a piece of bungee-cord to reduce the shock load) be a good safety connection then?<{POST_SNAPBACK}> Yes; but only if it is certified etc. Link to comment Share on other sites More sharing options...
Stu Posted March 17, 2005 Share Posted March 17, 2005 Another idea you could use for the attaching of safety bonds / chains to a t-bar setup is to use those half couplers which have a ring on the other side of them, most commonly used for attaching lines to tops of booms etc. Anyway then you can loop the safety through there... Stu Link to comment Share on other sites More sharing options...
Matt567 Posted March 18, 2005 Share Posted March 18, 2005 Would rope (including a piece of bungee-cord to reduce the shock load) be a good safety connection then?<{POST_SNAPBACK}> Yes; but only if it is certified etc.<{POST_SNAPBACK}> This of course wouldn't keep Mr Fire Officer happy. Has anybody ever seen a hook clamp fail? Link to comment Share on other sites More sharing options...
Brian Posted March 18, 2005 Share Posted March 18, 2005 Has anybody ever seen a hook clamp fail?<{POST_SNAPBACK}>I've never heard of a hook clamp failing as such. I've heard of lanterns falling because the bolts weren't secure and I've heard of lanterns falling because they were lifted up off the bar by scenery flying past. In the US it's diffferent; they use cast hook clamps with the chance they can fail, even days later, if you over tighten them. That's said, for the sake of a few pounds, it's better to be safe than sorry. Link to comment Share on other sites More sharing options...
Andrew C Posted March 18, 2005 Share Posted March 18, 2005 This of course wouldn't keep Mr Fire Officer happy. Has anybody ever seen a hook clamp fail?<{POST_SNAPBACK}> What's it got to do with him? And no, I've never seen a hook fail, I've never met anyone who has, nor have I spoken with anyone who has seen a chain doing it's job. Maybe it's just that I've worked in places where the bolts have been done up properly! :( As Brian says, some places do have higher risk factors, and they only cost a little and it's very little extra effort. Link to comment Share on other sites More sharing options...
Matt567 Posted March 18, 2005 Share Posted March 18, 2005 This of course wouldn't keep Mr Fire Officer happy. Has anybody ever seen a hook clamp fail?<{POST_SNAPBACK}> What's it got to do with him? <{POST_SNAPBACK}> Not a lot, but I would imagine he wouldn't be too happy about a safety device that that would burn in a fire......the same way that they're not too happy using spansets when theres no steel safety. Link to comment Share on other sites More sharing options...
Guest lightnix Posted March 19, 2005 Share Posted March 19, 2005 OK, I know that "bolts don't fail", <{POST_SNAPBACK}>You might believe that bolts don't fail, the existance of the guotes in your post indicates some scepticism but I have been standing under a lantern where the bolt failed in use and I was only saved because there was a safety. <{POST_SNAPBACK}>Pardon me - the scepticism on my part was towards other people's arguements (not mine) that "bolts don't fail" - they do and I know it. Your own experience backs up what I was trying to say, but failing to make clear (seems to be par for the course at the moment) :( Link to comment Share on other sites More sharing options...
Just Some Bloke Posted March 19, 2005 Share Posted March 19, 2005 Having just looked at this discussion for the first time due to being busy at work (I'm sure you all know how that is!), I'm a little worried that the following comment hasn't been sufficiently slapped down yet: Another thing I've always heard is you don't need safety chains on stage, only over the auditorium.<{POST_SNAPBACK}> This is COMPLETELY WRONG!! Everything that could fall needs secondary suspension. Read the thread about hanging lights in Maplins recently and you'll get the gist. In respect to the comments here about stands tipping over: if a stand has more weight on one side than the other, making it likely to tip one particular way, I like to tie the opposite leg to a stage weight (or two) to try to avoid that happening. I've seen several stands go over in my time and I'm just glad I've never been hit by one (yet!!). Everyone needs to take every precaution they can with stands. Just a couple of thoughts for those who are still learning (not that we ever stop!). Link to comment Share on other sites More sharing options...
ianl Posted March 19, 2005 Share Posted March 19, 2005 Has anybody ever seen a hook clamp fail?<{POST_SNAPBACK}> yes I've seen a hook clamp fail on 2 ocasions, in both the hook clamp peeled open and turned into a straight bit of metal,once the safety wire cought the light, on the other the safety chain snaped and the mains cable/15A plug cought the light Link to comment Share on other sites More sharing options...
the kid Posted March 19, 2005 Share Posted March 19, 2005 What kind of load was on the clamps for it to become a straight peice? it must of been a crazy load on a weak clamp. Link to comment Share on other sites More sharing options...
gareth Posted March 19, 2005 Share Posted March 19, 2005 What kind of load was on the clamps for it to become a straight peice? it must of been a crazy load on a weak clamp.<{POST_SNAPBACK}>My thoughts exactly - for a bog-standard hook clamp to "peel open and turn into a straight piece of metal" you'd have to be applying an absolutely phenomenal load to it. The worst instances of damage that I've ever seen to a hook clamp are ones which have bent a little at the 90-degree corner directly above the wing-bolt - often because some numpty has tried tightening up the wing-bolt with a really big AJ. But to actually bend the clamp into a straight piece of metal?!?! On top of which, apparently somewhere out there there's mains cable and 15A connectors that are strong enough to catch a falling load which has already bent a steel hookclamp and snapped a safety bond! I have my suspicions that Ian might just be exagerating a little bit! ;) (Or buying hook clamps made from Bacofoil :P ) Unless, of course, he can furnish us with a slightly more in-depth explanation of how this gross deformation of the clamp actually occured .... I'm particularly keen to know what was hanging from the clamp to cause it to fail in such a way, and to know what these connectors are that seem to possess some sort of magical load-arresting power which can deal with forces large enough to bend a steel clamp and snap a metal chain ... :( Link to comment Share on other sites More sharing options...
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