Mounting lasers on stage

[Jem]

Cheers Ian,
I know you're fairly knowledgeable in that sort of area, so could you suggest a decent tripod if the ones I suggested are naff...?

Hey Dan

These are what i'm using... Rock Solid

http://www.mypowerdrive.com/asp/news/newspage.asp?id=6

Jem

[White-Light]

One thing you could do to improve your safety for audience scanning is fit a Pangolin PASS system. Not cheap, but so robust that its passed for audience scanning in the US by the FDA, thats no mean feet.

Details on the PASS system are here but basically it monitors the scans and cuts out anything thats unsafe:

http://www.pangolin.com/PASS/index.htm

[danielbriggs]

Hey Dan

These are what i'm using... Rock Solid

http://www.mypowerdrive.com/asp/news/newspage.asp?id=6

Jem

Cheers Jem
Pricey but look good. I'm only gonna buy one, so might as well make it a gudd'un

Ta,
Dan

[mixedgas]

Somebody find this guy the FDA pdfs I posted a year ago with the actual math.

Steve

[Carl B]

Without meaning to threadjack;
Could I just ask recommendations of a half decent stand for my "Toblerone" rig?
I've seen these two; any preference?
http://www.dolphinmusic.co.uk/produc...ker-stand.html
http://www.djkit.com/product.php?id=2290&cat=278

I was planning to make a plate (from some really thick kitchen top laminated chipboard cut to the size of the base of the triangle), screw on some square section around the edges for location, and mount a top hat adapter on the base for mounting to the stand.
Can anyone advise on a better way to do this? I don't really want to mount the tophat adapter directly to the aluminium base...

Ta,
Dan

Ask Kevski if you could have a look at his Stand. He bought the same one as I have from CPC. They are well built and very robust. Cost about £90. Avoid stands that don't have a safety pin for the upper half of the post.

Carl

[mliptack]

I wouldn't call it an obsession, I prefer to use trussing where possible but sometimes it's not.

My projector weighs about 60lbs, my tripod is rated at 3 times that and has a rack and pinion winch that raises it to 10 feet. Even at maximum height it is rock solid and the legs have a spread of 6 feet. It's no lightweight itself though, but it will fit into a medium sized car and is a godsend at 5am when you are packing up.

Just an FYI (after re reading my post and this thread since last night) I didn't mean to come off harsh either. I just always saw it as being odd that *everyone* uses tripods. I am glad you know the limitations of your tripod, I too have some *very* nice tripods, but oddly enough, I still don't like to use them. The main reason why is they are so easy to trip over. Even if it only slides that still knocks the alignment of your projector. One inch change here, and a 15-20' difference out in an audience.

Many times for shows we have these 240lb bases that are only 3/4" thick (approx 4' square) they are made for vertical truss sections. I made a curved goalpost outdoors that was 20' tall and about 300' long with 12x12 truss. Using only 11 of those bases (talk about no easy feat!) but ROCK SOLID... of course I am not suggesting something that long for a laser

Respect!
So how were the lasers mounted?

Thanks! Honestly I don't recall. I didn't deal with them too much. There were 2 crew guys and 2 Union Labor hands to load all of lighting in. So lunch could easily be pushed back to dinner time/show. Also just to specify this was on the US/Canada tour - not sure how it was elsewhere.

Yeah I saw The Wall tour this year, light show was a bit disappointing to be honest. To make up for it I am seeing this tomorrow

I've never seen them... although I do enjoy floyd, I should at some point try to get to see them. I missed the APF show this year, the closest they came to us was Rosemont, IL., and I was working somewhere else...

but that's only because the linear distance around a tunnel is a lot longer than the diameter of the tunnel. The laser is tracing over a longer "line", thus the average power along that line is lower.

However, if you instead compare the circumference of the tunnel with the width of the fan, your calculation yields the same energy density. (Which, as we've already discussed, ignores the fact that there will be slight "hot spots" at the ends of the fan, which you obviously won't have with a continuously-scanned tunnel.)

This reminds me of a simple physics demo: you see a rotating disc, on the disc there is a red peg. looking at the surface of the disc you see the peg going in a circular path. But now change your point of view so you are 90 degrees from perpendicular to the disc (you should be looking at the side of the disc). Now you will see the peg making a linear travel up and down. I cant remember what this idea of physics was called...

Another theoretical physics argument: what happens if you dug a hole through the center of the earth and jumped in? You would accelerate until you hit the center of the earth, then as soon as you passed you would begin to accelerate in the opposite direction. So you would be just going back and fourth forever (neglecting friction of course). But how long would one "cycle" take? In theoretical practice it would take approximately 90 minutes. But why....? Open ended question... anyone got the answer?

Sorry I got a bit sidetracked by one of my favorite things... physics...

[Doc]

Dan, the tripod that Jem linked to looked like a better option. Mine uses a rack and pinion rather than a cable and was from CPC but I don't see it in the current catalogue.

Remember; tripod = no use on a timber stage or as Steve mentioned; lots of bass = fuzzy beams, or worse lots of bouncing = potential danger.

The tophat piece attaches to the equipment permanently and intudes in to the case by about 2"



Mliptack;

I'm guessing that the answer to your question is based on an inititial acceleration value of 9.98ms², slowly diminishing as gravity is progressively balanced by the mass that would be behind you as you journey through the mass?

[smokeAndMirrors]

The hole-in-Earth problem just looks like a simple harmonic oscillator to me, so start with the ODE for that and a force term that -GMm/x^2 where G is the gravitational constant, M is the mass of the earth, m the mass of you and x the radial coordinate. Provided you can solve that ODE then the period will drop out just like in the basic case.

[mliptack]

@Doc, yeah those are all too common on speakers. I wonder if you can buy the ones on the Mackie powered speakers... that have the threaded screw knob on it. Which allows you to tighten it down to the stand.

@SAM remember this is intro to physics... using my round peg example in reverse what would that be like that we observe on earth? I cant get any more descriptive w/o just giving it away.

[Adrian Cavaleru]

Dan, the tripod that Jem linked to looked like a better option. Mine uses a rack and pinion rather than a cable and was from CPC but I don't see it in the current catalogue.

Remember; tripod = no use on a timber stage or as Steve mentioned; lots of bass = fuzzy beams, or worse lots of bouncing = potential danger.

The tophat piece attaches to the equipment permanently and intudes in to the case by about 2"



Mliptack;

I'm guessing that the answer to your question is based on an inititial acceleration value of 9.98ms², slowly diminishing as gravity is progressively balanced by the mass that would be behind you as you journey through the mass?

I'm just curios how will you fit that piece of junk inside of an already built projector