Rigging guys... a question

[Bradfo69]

I've thought about that. In a perfect world, there would have been acoustic tile ceiling over the stage and I could have rigged something with a bracket that poked through the tile and just swap the tile out when necessary. With it being drywall, I'm a little more limited since I also don't want something unsightly when it's not in use. Plus, the retractible projector screen is in the ceiling right there too so I need to think about that clearance.

Thanks for the links norty - that kit with the 3 sections of triangle truss is a pretty good deal even with the exchange rate - I'd just have to calculate shipping. I'm trying to locate vertical truss adapters in the states. Quick search turned up nothing but, I'm at work and only had a few minutes to start looking.

[norty303]

Contact thomann for a quote, they have an international shipping rates thing on the site, but I suspect they'll need to work it out for you. Tell them what you want, they'll respond quite quickly.
If you can't find vertical ones in the States, I have 3 pairs of the ones in the Thomann link, so could probably spare a pair. Depending on shipping it might jst be cheaper to get them from thomann as it'd be a 30EURO flat rate up to 31KG

http://www.thomann.de/gb/helpdesk_sh...ml?country=usa

[Bradfo69]

The big issue you will have is actually not the loading, but the fact the truss will start to deflect forward or backward, as it basically has no strength in that axis. I'm talking from experience of an 8m span here, that started oscillating back and forth under very minor shocks through traffic on the stage.

One other question... deflection. You're saying back and forth. That doesn't make sense to me. Isn't deflection how far the center of the truss can dip down in the middle? If you're supporting a long pole from both ends, the natural weight of the pole is going to cause the center to bow downwards. I thought deflection was that measurement downward towards the ground away from it being truly level. Kinda like the middle of a tennis court net cable not being tight. I don't understand "back and forth". Am I not grasping the correct definition?

[norty303]

Deflection can be in any axis, although they assume to mean down because thats where the load is right?

However, in practise, if you use a piece of F32 in the vertical axis over a span in excess of its rated span, load it up a bit so you see a bit of deflection, then give it a little push or bounce on a less than stable floor (temporary stage for example) you will see deflection in the back and forth axis, sometimes alarmingly so, due to the mass of the fixtures. This will be worse if any fixture is not hanging directly under the bottom chord, or there is anything overhung. I beam/ladder truss simply doesn't have any rigidity in this axis, and so big spans really show it up.

The tennis net has relatively little mass, so any oscillations are small and quickly stop. Hang a big weight in the middle and you'll find it takes much longer to stop,and will probably deflect further.
A single pole reacts differently to bi-beam truss. The single pole reacts more like a pundulum, the bi-beam seems to be more linear in movement.

It was being in exactly this position that caused me to buy my F33. I hadn't considered for a second that I would encounter back and forth deflections until it did, and by then it was too late to do anything about it.

[Bradfo69]

Gotcha. Thank you! I'm probably just going to hold out for box truss then. The hard part I suppose is going to be finding someone interested in buying 2 brand new - 16" baseplates and 2 brand new 6.5 foot sections of I-beam for anywhere close to the $500 I spent.

Edit: Let this be a lesson to you kiddies... don't get addicted to lighting and lasers. You buy shit you don't need. LOL

[Bradfo69]

Well.... I did the deed. 'Tis only money.

I got this...

http://www.ebay.com/itm/400590008145...84.m1423.l2649

and then added another meter of F33 so the legs of the stands clear the stage at a 24' width. It's still not as long as I would like but should suffice for now.

The one question I had Adam, is as it relates to this:

If you want to use the F32 as a t bar you will need another set of adapters, probably a 35mm to 28mm TV spigot adapter and a half coupler on a 28mm TV spigot.
I'll take some pics of mine later if that doesn't make sense. In fact I could take pics of all the adapters for single bar, F32 and F33 if you like.

So, do I need something else besides the vertical truss adapters I just bought from you? (If I periodically want to use the ST-132's as sort of "T" stands for the 2 meter sections of I beam I have?)

Thanks!

[norty303]

Yes, you cannot use the F32 adaptors as T-bar mounts, they don't actually clamp the truss, the truss just sits in them (albeit locked in place, but not clamped solid. This allows you to crank end by end on your own, as the truss will tilt in the mount)
That's why I said you need the half couplers in my previous link, as these clamp the truss/scaff bar tight. You need a different piece to do each job, half coupler for T bar, vertical adaptor for F32 and horizontal for F33/34. Personally I would just get a couple of 48mm aluminium 1.5m bars (very cheap) toi use as T bars, rather than ladder truss. The truss offers no benefits over plain bar when used as a t-bar, and some disadvantages (i.e. you clamp the top bar, the truss cannot hang vertically due to the stand. You clamp the bottom chord, the top tries to fall backward/forward all the time, putting twisting load on the clamp)
Ask the vendor if the ST132's come with the square t-bars, they should do what you need. All of ours in the EU have done.

Also, DO NOT EVER mount your truss the way be has it in the pictures. The adaptors should be inside of the last cross brace at the very least, not on the bare end.
A swift kick to the stand could cause the truss to pull out of the adaptors. They are not clamped, just resting in there.

[Bradfo69]

Thanks. That's one reason why I bought an extra small section of F33.

I may have to go with your suggestion of a couple of 48mm aluminum bars as I know this set does not come with the T bars. Most every web site over here seems to sell the T bars separately from the stand. I don't really "need" it as I mentioned I have about 7 - T stands already. I've just been trying to figure out "some" way using the stuff I already bought. Think I may have to just list it on eBay... I'm not coming up with a working solution. That's about 500 pounds translated in your money thrown out the window.

[norty303]

If your other stands are a 35mm top then you do have the option of another truss bridge using the vertical adaptor sand F32 lengths