Solenoid Actuated Spring FX

[redshiftcreation]

Working on a production that needs to make a bunch of papers fly into the air. Haunted writer type play.

So, what were are thinking is a lever that is on a spring that a pull solenoid holds in a depressed position, and then at the moment effect is needed, pull the pin out of the catch, release the spring, papers fly.

My concerns are the pressure from the spring bending the solenoid, and also am very new to this sort of work so advice on types of solenoids, wiring, etc. would be appreciated. Also, since this catch would probably be something that had to be loaded by hand it may be left in the deployed position until someone can get to it to reload or otherwise mask.

Plan B involves an electromagnet that would hold said spring loaded lever in place, and then when electricity is killed manget demagnetizes and releases the papers flying.

Thoughts? Anyone done something like this before? Any words of wisdom would be appreciated.

David

 

[sk8rsdad]

Something similar was discussed in another thread that I cannot locate.
[EDIT by DL: This one? http://www.controlbooth.com/forums/scenery-props-rigging/25724-flying-paper.html ]
I think the solution I suggested then was to load the paper into a hopper and use a motorized rubber wheel to fling the paper out. The rubber wheel likely needs to be on some sort of swing arm to maintain contact with the paper.

 

[redshiftcreation]

Thanks, but that isn't exactly what I'm talking about. This is flinging papers off a desk, not so much dropping from the sky. Like, stack of manuscript that magically flies off of desk when the spring loaded lever is released. Thanks though. Sorry wasn't more clear.

 

[sk8rsdad]

I think the solution works in either case. The only difference is the orientation of the hopper.

 

[beachbum]

We have often used solenoids as triggers--they seem to work best when used indirectly. Try using the solenoid to pull the pin on a latching device rather than using the solenoid bar itself to hold the effect in place, that way the solenoid can be mounted where it makes the most sense, and not necessarily on the effect. It takes a certain amount of trial and error to get everything right, but the simplicity of the device makes it pretty reliable. They come in a variety of sizes. Make sure the stroke length and pull force will work for your needs.
Solenoid, Laminated - Mechanical Solenoids - Solenoids - 4X894 : Grainger Industrial Supply A momentary contact switch is probably best, since the solenoid will vibrate loudly if power is inadvertently left on. Small pneumatic cylinders also make great trigger pullers, if you have access to them

 

[silicsound]

I'm not sure how far you want to the paper to fly. But a stack of paper would more jump over the side rather than fly if you used a spring mechanism. In my experience, you need a large solenoid if you need to pull a pin with pressure on it, like you describing, it would be much simpler if you had a stagehand pull the pin with a rope. You should not use Plan B(electromagnet), the risk of it being accidentally set off is pretty large if some knocks out the cable or mechanism lost power.
I would use a group of compressed air nozzles to blow the paper off the desk. Or the mechanism that sk8rsdad was describing.

 

[redshiftcreation]

I'm not sure how far you want to the paper to fly. But a stack of paper would more jump over the side rather than fly if you used a spring mechanism. In my experience, you need a large solenoid if you need to pull a pin with pressure on it, like you describing, it would be much simpler if you had a stagehand pull the pin with a rope. You should not use Plan B(electromagnet), the risk of it being accidentally set off is pretty large if some knocks out the cable or mechanism lost power.
I would use a group of compressed air nozzles to blow the paper off the desk. Or the mechanism that sk8rsdad was describing.

You are totally right about compressed air nozzles. That was the ideal solution. Unfortunately its just out of budget range.

Looked into string option, but this happens at a point in the play where basically every FX we have is going, and we have no hands to spare unfortunately. Hence trying to get it controlled via lx console.

The hopper poses budget issues, as well as just plain size issues. It needs to happen from on top of the writer's desk, i.e. no place to hide a hopper and we don't wan't the paper to magically appear, we need the players manuscript he has been carrying as a hand prop the entire play to get thrown. I may misunderstanding what you mean by that system, but it sounds like the actor couldn't put the manuscript down on the desk, and then have the manuscript he placed down go flying with that sort of set up.

So, what we are going to try to get to work is a automatic car door opening solenoid stepped down from line voltage w./ a live load (work light) on same circuit working as trigger to pull a pin on some sort of spring loaded device. Will let you know how well it works, if at all. Hopefully the powers that be will make it work, wish we had the money to go compressed air as that is something I would be much more comfortable with. The curved walls and spiral stair set ate up most of the budget pretty fast.

Thanks for all your help.

 

[DuckJordan]

If its too expesive for air its too expensive for the size of solenoid.

 

[Van]

If its too expesive for air its too expensive for the size of solenoid.

It's been my experiences that Pneumatics are diffcult to use with Paper. Do this experiement: Fold a piece of notebook paper in half, now bend two 'legs' down and set this on a tabletop. The middle of the paper should be about an inch off the desktop. Now, Blow under the paper, through the airspace. The "bridge" will collapse, bending down in the middle. Yes, you are pushing a lot of air through and you would think it would act like a solid or a liquid and just push the paper out of the way. Nope, the large quantity of air rushing under the paper creates a low pressure area and the atmospheric pressure on the other side of the paper presses down on it . Now when you try to do a stack of paper the same thing happens , If the weight of the paper is sufficient to overcome the initial blast < and it doesn't take much> then the large volume of air moving under the paper creates the same low pressure area and the atmospheric pressure will keep the stack from moving.

I Kind of like the idea of the lever, a spring loaded board, but I was thingking along the lines of a Wire Bail. Somthing like a giant Mousetrap. It would live under the paper the pin of the solenoid holding it down, then when the pin is reatracted the bail springs free, flings the paper, and comes to rest flat against the desktop. you could hide the solenoid under the desktop and have a small wire running through the desktop that would act as the retaineruntil released.

Hope that helps