Nick LX Posted June 1, 2008 Share Posted June 1, 2008 Hi,I am planning on having an upright square truss which will be attached to a heavy duty base plate. It will also be secured to an upright pole which is set in the ground with concrete. What I am wondering, is if it is possible to rig a moving light on the side of the truss. Hope you understand. Thanks Link to comment Share on other sites More sharing options...
iamchristuffin Posted June 1, 2008 Share Posted June 1, 2008 Yes it is - make sure that the truss is stable enough to take the 25+ kilos that the moving light puts on one side. The higher up the truss the mover is, the more force needed to counteract it. HTH, Chris EDIT: PLEASE NOTE: As Ynot pointed out below, I have no real-world experience. This is purely based on common sense and AS level Mechanics! Link to comment Share on other sites More sharing options...
Nick LX Posted June 1, 2008 Author Share Posted June 1, 2008 Well, it is only 3 metre high truss. There will be a mover on each side. Thanks Link to comment Share on other sites More sharing options...
Ynot Posted June 1, 2008 Share Posted June 1, 2008 Yes it is - make sure that the truss is stable enough to take the 25+ kilos that the moving light puts on one side.Sorry, Chris, but you base this definitive answer on what, exactly?Experience?Training?Back of a fag packet guesstimation....? It will be feasible to do what the OP is suggesting, BUT there are several things to bear in mind. If the moving heads are going near the top of this 3m truss, then there is a definite potential for a LOT of stress to be placed on the supports. I sincerely doubt that any of the head movements will be synched in any way to counteract each other, so there are going to be a LOT of varying forces pulling the truss every which way. The OP also doesn't say what ML's he's looking at...Tin-pot disco movers, or heavy duty VL's are at opposing ends of the weight ratio scales... This is not something I would contemplate without a good deal of investigation, to be honest - and certainly not on the basis of having discussed in an insecure 'net forum. The potential for 10 feet of truss being pulled over with a fair weight of moving heads on the top is to be quite frank a bit of a high risk... Link to comment Share on other sites More sharing options...
iamchristuffin Posted June 1, 2008 Share Posted June 1, 2008 Sorry, Chris, but you base this definitive answer on what, exactly? Whoops! Wasn't mean to be so definitive! I've added a disclaimer at the bottom of my 1st post! Sorry, Chris Link to comment Share on other sites More sharing options...
Nick LX Posted June 1, 2008 Author Share Posted June 1, 2008 <snip> If the moving heads are going near the top of this 3m truss, then there is a definite potential for a LOT of stress to be placed on the supports. I sincerely doubt that any of the head movements will be synched in any way to counteract each other, so there are going to be a LOT of varying forces pulling the truss every which way. The OP also doesn't say what ML's he's looking at...Tin-pot disco movers, or heavy duty VL's are at opposing ends of the weight ratio scales... This is not something I would contemplate without a good deal of investigation, to be honest - and certainly not on the basis of having discussed in an insecure 'net forum. The potential for 10 feet of truss being pulled over with a fair weight of moving heads on the top is to be quite frank a bit of a high risk... Literally the upright square truss will be in a 75kg base plate, and also secured to an upright pole which is set in the ground with concrete (ie it is permanent.)There will be 2 Mac250+ ML which are 22.0 kg each. Obviously I won't only use your advice, but I thought here would be a good idea, because I wanted to know if it was worth contemplating. Link to comment Share on other sites More sharing options...
gareth Posted June 1, 2008 Share Posted June 1, 2008 As long as you use appropriate kit to secure it to the concreted-in pole, and the final structure is pretty well balanced in terms of its centre of gravity, then I don't really see any problem with doing what you describe. (And I have quite a bit more experience than Chris Tuffin's "none" ) It's probably worth adding, although you probably already appreciate it, that any advice you receive through this or any other internet forums can only be taken for what it actually is - informal generic advice, given without any specific knowledge of the particular situation that you're facing or the specific risks involved. As with any other rigging project, if you're at all unsure it's best to seek professional advice. Link to comment Share on other sites More sharing options...
smalljoshua Posted June 1, 2008 Share Posted June 1, 2008 secured to an upright pole which is set in the ground with concrete (ie it is permanent.)How sure are you on the stability of the post? It may be Just in the ground a couple of inches or it could be in the ground a couple of feet. Unless you are sure it is a strong point to attach to I wouldn't be relying on it. Josh DISCLAIMER: I have not got any real world experience of this. I am basing it on what I have learnt in my GCSE Engineering class. Link to comment Share on other sites More sharing options...
Nick LX Posted June 1, 2008 Author Share Posted June 1, 2008 Although it isn't part of the building, it is a permanent bar for rigging lights. it doesn't come out of the ground. Link to comment Share on other sites More sharing options...
bruce Posted June 1, 2008 Share Posted June 1, 2008 I have no real-world experience. This is purely based on common sense and AS level Mechanics! DISCLAIMER: I have not got any real world experience of this. I am basing it on what I have learnt in my GCSE Engineering class. C'mon chaps. You both admit that you have no experience in this area. So why do you feel the need to post something? The original post asks for advice in an area where safety is paramount. I probably have more knowledge about the theory behind this than either of you two - I certainly have more relevant letters after my name than "GCSE engineering" or "AS mechanics" - yet I do not feel qualified to comment. So I didn't. I may have a "gut feeling" about whether it would be OK or not, but I wouldn't dream of posting that on a professional forum. There is little risk of a question going unanswered - there are plenty of experienced folks here. If none of them have contributed after a considerable time, then perhaps it would be valid to post your comments, with appropriate disclaimers. But leave it for a while. Link to comment Share on other sites More sharing options...
Nick LX Posted June 1, 2008 Author Share Posted June 1, 2008 I have no real-world experience. This is purely based on common sense and AS level Mechanics! DISCLAIMER: I have not got any real world experience of this. I am basing it on what I have learnt in my GCSE Engineering class. C'mon chaps. You both admit that you have no experience in this area. So why do you feel the need to post something? The original post asks for advice in an area where safety is paramount. I probably have more knowledge about the theory behind this than either of you two - I certainly have more relevant letters after my name than "GCSE engineering" or "AS mechanics" - yet I do not feel qualified to comment. So I didn't. I may have a "gut feeling" about whether it would be OK or not, but I wouldn't dream of posting that on a professional forum. There is little risk of a question going unanswered - there are plenty of experienced folks here. If none of them have contributed after a considerable time, then perhaps it would be valid to post your comments, with appropriate disclaimers. But leave it for a while. Do you have a gut feeling? Also for extra support would it be worth putting diagonals in to balance it? Link to comment Share on other sites More sharing options...
bruce Posted June 1, 2008 Share Posted June 1, 2008 Do you have a gut feeling?Yes I do. But I don't feel that it would add any value to this discussion. Also for extra support would it be worth putting diagonals in to balance it? I guess you mean "brace" rather than "balance". The answer is, as with all these things "it depends". You don't say how the truss is going to be linked to the vertical pole. You don't give details on the truss itself - is it "industrial strength", rated and certified truss, is it stuff that is intended for "Dave the DJ", or is it something in between? I would suggest taking advice from either the truss manufacturer, a structural engineer, a rigger etc - ideally one who has either seen the installation, or a drawing. Link to comment Share on other sites More sharing options...
Nick LX Posted June 1, 2008 Author Share Posted June 1, 2008 It is this: http://www.litectruss.com/en/prodotti/deta...mp;TipoLayOut=0 with a 75 kg base plate. Thanks Link to comment Share on other sites More sharing options...
AndyJones Posted June 1, 2008 Share Posted June 1, 2008 Hello It's decent enough truss I see no issues with it providing ground is level and solid. Maybe add some stage weights for ballast aswell? One extra thing worth noting is that it's probably best to not be using the standard mac hook clamps. Try and get some half couplers to attatch the movers to the truss. and put an LED at the bottom of the truss to make it look pretty As said before make sure that you get some one competent to over see the rigging of said structure and for final clarification I would give the truss manufacturers a call. and run it buy there guys to make sure it's safe as I can't seem to find any definitive load tables on that site. HTH AndyJones Link to comment Share on other sites More sharing options...
Nick LX Posted June 1, 2008 Author Share Posted June 1, 2008 Here is the load table I found: http://www.pslx.co.uk/Datafiles/Litec/QX30S.pdf Definitely helps alot, and will make sure to get it checked out first. Thanks Link to comment Share on other sites More sharing options...
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