John Palmer
Well-Known Member
That's what I thought looking through the handbook as well.
JP
JP
Can you identify these architectural ellipsoidals?
- Thread startergafftapegreenia
- Start date
Okay...
@Van : "What exactly was you lugging around in high school then?"
(besides my sister :rimshot: )
Would that make @Van a 'bugger lugger' , a 'lugger bugger' OR ? So long as it didn't make him a 'curmudgeon cuddler'.ZING!
Toodleoo!
Ron Hebbard.
Dennis Degen
New Member
BillConnerFASTC
Well-Known Member
Silicon_Knight
Active Member
Out of an interest to broaden my knowledge from those who are vastly more experienced than myself, what's bad about using threaded elbows and T's on a bar installation like this? I thought this type of mounting seems pretty common.
@Silicon_Knight The worry is the threaded pipes rotating due to the effect of gravity on the eccentric weights of instruments yoked up or out. It would be possible to use threaded pipes and fittings and tack weld them once assembled.
Toodleoo!
Ron Hebbard.
@gafftapegreenia I'll buy that for threaded pipes supported vertically or horizontally from one end. Not so much for threaded nipples supported from both ends.
Toodleoo!
Ron Hebbard.
BillConnerFASTC
Well-Known Member
They have no structural rating. Generally riggers do not use products and materials for which there is no testing or rating whatsoever, especially when like in this case there are so many products that are rated and you can design for the usual 8:1 or 10:1 breaking strength to design load. What is the breaking strength of a threaded pipe connection like these? Not as simple as bolts since pipe threads are tapered.
PS: This is kind of interesting. http://www.ebtx.com/mech/pipes.htm Hard to google for the structural strength of threaded pipe connections - a lot "pressure" as in steam pressure.
PS: This is kind of interesting. http://www.ebtx.com/mech/pipes.htm Hard to google for the structural strength of threaded pipe connections - a lot "pressure" as in steam pressure.
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@BillConnerFASTC The effect of the tapered threads becomes even worse when electricians create "running threads to fully engage a standard coupling and jam nut when assembling pipes that can not be rotated when being assembled.
Toodleoo!
Ron Hebbard.
Silicon_Knight
Active Member
Great info, all - thanks. So, what is the best alternative to mounting to a bar full of lights to a wall (like what was done in the picture at DIA)?
The LightSource grid hardware, Kee Klamp, Interclamp, Cheeseborough and other tube & clamp fastening systems can be engineered for this. The key word there was "engineered".
BillConnerFASTC
Well-Known Member
First choice IMHO is miter cuts or coping and (shop) welding. and a lot use a steel angle bracket with U bolts to hold the pipe. A lot of riggers will go clamp type fittings if appearance is not a priority. DIY maybe rota-locks (not roto-locks - those are coffin locks). I would not eliminate speed rail and that type if it has a rating. And I've seen an internal "L" that I think n is rated - expands with set screws IIRC.
JonCarter
Well-Known Member
Ron, IF the pipe fittings (angles at both ends or angle/tee at the ends of a horizontal pipe) are made up tight, even if an instrument's "C" clamp should attempt to rotate the pipe, it would try to loosen one end and tighten the other end. Probably very little or no rotation at all. And, if the instruments are hanging "down" as in the photo there will be no torque on the pipe anyway.
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JonCarter
Well-Known Member
"No safety cables!" Well, let's safety cable the yoke to the pipe. Oh, then maybe the yoke bolts might fail. Well, let's safety cable the instrument to the yoke. Oh, then maybe the lamp cap could fall of the instrument. Well, then let's safety cable the lamp cap to the instrument. Oh, well then maybe the gel frame could hop out of the slot. Well, then, let's safety cable the gel frame to the instrument. I'm all for safety, but come on, folks. When have you ever seen an instrument fall off the pipe?
@JonCarter Fret not. Both our resident curmudgeons will find fault with it anyways. Trust me on this.
Toodleoo!
Ron Hebbard.
EdSavoie
Well-Known Member
Not often, but watching a disco ball with only a single point of attachment coming crashing down is once enough. We were lucky that the bar was lowered while we were gelling and swapping other fixtures when it decided to just drop off the bar without warning.
With regards to a normal fixture, why risk it? It's such a simple thing to do, and all you need to do is forget a wrench one time for the sizable risk to be there, especially if for example an error causes an electrical to be raised above a teaser at decent speed, giving a larger fixture a decent thwack during a hectic set change.
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