Members StratGuy22 Posted June 13, 2013 Members Share Posted June 13, 2013 Hi, I was wondering, on a load chart for truss, is the weight of the truss included in the load? Say I'm looking at a 250mm aluminum triangle truss, that weighs 10.7kg On the chart, a 5m spam (2 truss lengths) with a 90kg load will have a deflection of 12mm according to this chart. http://www.soundking.com/html/Products/Category_display/professional_show_instrument/3/2011/0222/832.html Is that 90kg load, the load itself, or is that the total load including the 10.7 weight of each truss, (21.4kg) Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 13, 2013 Author Members Share Posted June 13, 2013 As much as I wanted triangle truss, after looking at the specs, square truss is a no brainier. The difference in load bearing is huge. I'd be close to the limit with my master plan, with the triangle truss at a 16' length. At 20' it's not possible, with the full load. (250lbs) The load doesn't even sag at a 16' length, and at a 20' length, the load I have planned, would sag 10mm. The 20' length can support 529lbs with an 18mm sag, so it will be comforting to know I'm at half the limit. Sure these things are over engineered, but just because it may hold 2x spec in reality (I have no clue) if I'm doing this upgrade, I'm doing it right, and will load it well under spec. So it will cost more than I was expecting, but peace of mind, and knowing I'm doing it the safe way, and the right way is priceless. Link to comment Share on other sites More sharing options...
Members Miko Man Posted June 13, 2013 Members Share Posted June 13, 2013 Truss is a ways down the road in my long-term planning, but I have already decided that square truss is the way to go. Plated (bolted) construction (3mm wall thickness) vs pinned connectors (2mm walls) is the next decision point, but I don't have to worry about that decision for a while. (If I ever get that far....) Mark C. Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 13, 2013 Author Members Share Posted June 13, 2013 Yeah I'm going with the aluminum box truss. The difference is pretty big between that and the triangle. Link to comment Share on other sites More sharing options...
Members BillESC Posted June 13, 2013 Members Share Posted June 13, 2013 I don't know what brand of truss you're considering but the ratings you've listed seem poor at best. For example, Trilite's 212B (12" box tuss) is rated for 2,719 pounds for a 20' span. Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 13, 2013 Author Members Share Posted June 13, 2013 This is what I have to choose from. http://www.axemusic.com/store/product/25088/Soundking-11.4%22-x-11.4%22-x-8.2%27-Box-Truss/ These are the specs according to the website http://www.soundking.com/html/Products/Category_display/professional_show_instrument/3/2011/0222/830.html Believe me, it's a pain being in the middle of buttfcuk nowhere. I'm 3 hours from Edmonton, the nearest city, and I need it tomorrow. With a total of 260lbs of load it doesn't really matter if the upper spec is 545lbs or 2000lbs as far as I can tell. It will be an improvement from the radio tower I was using up until now... The real part that hurts is the clamps are $20/each and I need a dozen to start. I'm sure I can get them cheaper elsewhere, but again, I need them tomorrow. Plus I have to rent another FOH setup (2 - LS800p's and w Unity15's) to run 2 full systems for bands due to a double booking at the bar. So it will be 5 bands from 6pm - 10:30pm at one venue, then 2 bands from 11pm - 1:30am. It will be a busy day to say the least. I could maybe even find the clamps cheaper in the city, but time is at a premium and I just don't have the time to run all over the city along with 6 hours of driving. The good news is, once I return I can set up the one venue tomorrow and the other one on Saturday, so that part will go smoothly, with lots of time. Then it's game on at 6 and that will take me until 3am the same night. Then I can load out of both venues on Sunday. So sometimes you just have to take what you can get. I was actually planning on waiting until after my high dollar Canada Day 2 day event (June 30, July 1) but I just don't want to chance the radio tower antenna anymore. Especially with my heavier light setup Maybe I'm misreading the chart. Each piece is 2.5m which will give me a 5m span. And eventually a 6m span when I add an extra 1m piece. Link to comment Share on other sites More sharing options...
Members soundlight Posted June 13, 2013 Members Share Posted June 13, 2013 I think you are misreading the chart - you're not going for CPL (Center Point Load) specifications - which are a single weight at the center - you wanna look at UDL (Uniform Distributed Load) specs because your gear will be spread out on the truss. Your load (250lbs/114kg) will only cause less than a 3mm deflection spread across the whole truss (114kg/6m=19kg/m). The UDL table is listed in kg/m (kilograms per meter, so weight per distance), so you can really comfortably go above 100kg/m, which would be 600kg, and not see much over 10mm in deflection with a mildly uneven load distribution. At that point though you'd probably be over the limit of your crank stands.In short, you could definitely go with triangle for your specified load, but box is better because it gives you a cable tray on top, and allows you more hanging options for fixtures.(This post brought to you in part by the wonderful Google search bar calculator.)ETA: What clamps were you planning on getting? Clamps are something that a lot of rental houses have extra of - you might be able to just rent a dozen clamps for real cheap rather than buying the wrong clamps for the job. Slim wrap-around O-clamps or trigger clamps are the way to go with truss - you don't want to use C-Clamps because they bite in to the truss and leave marks all over it. Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 13, 2013 Author Members Share Posted June 13, 2013 Nice! I DID misread the kg/m. For some reason I thought it was the full load for the span. It WAS 3AM What I do like about the triangle truss is that I can set up along that bottom rail like this, for more headroom.... Yes this is radio tower. Ignore that, and notice the pinspots on the same leg as the blizzards. http://i1187.photobucket.com/albums/z398/robare99/D8AF3133-577D-42BE-841C-53D2A78E6A47-15047-00000B60A44A6F39.jpg That saves me headroom vs the pinspots on the top like this... http://i1187.photobucket.com/albums/z398/robare99/3EE9DBB3-21EA-4BB8-A7C9-77CEC112436B-2443-0000022AD84D4BEC.jpg Instead of pinspots I want to mount Intimidator Spot Duos Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 14, 2013 Author Members Share Posted June 14, 2013 The box truss listed will actually hold 3175lbs on a 20' span I misread the chart, it was late. -blush- I was back and forth from box to triangle. So whatever they have 2 of tomorrow is what I'm getting. It sucks because the warehouse is about 2 blocks from the store but a monumental pain to try to get anything from there. Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 14, 2013 Author Members Share Posted June 14, 2013 ETA: What clamps were you planning on getting? Clamps are something that a lot of rental houses have extra of - you might be able to just rent a dozen clamps for real cheap rather than buying the wrong clamps for the job. Slim wrap-around O-clamps or trigger clamps are the way to go with truss - you don't want to use C-Clamps because they bite in to the truss and leave marks all over it.----------------------------------- Here's the clamps I have. 4 of the left, a few of the right. I plan on using the left ones if they fit. http://i1187.photobucket.com/albums/z398/robare99/B51C60A5-CAC7-4763-B434-FB01A84954AB-646-00000070C0B29BDB.jpg Then these are the ones I'm hopefully getting tomorrow. http://www.axemusic.com/store/product/8673/Chauvet-CLP10-Pipe-Clamp/ Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 14, 2013 Author Members Share Posted June 14, 2013 We were able to get the triangle truss which I wanted. And a dozen of those wrap around style clamps, so it all worked out. Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 15, 2013 Author Members Share Posted June 15, 2013 Link to comment Share on other sites More sharing options...
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