automatic front door opener (stage prop)

[paceman]

hi all,

bit a quirky one here...

i am trying to build a small prop for an amateur stage production and one of the requirements is a front door on a frame that opens outwards (toward the audience) by itself, quite quickly...

i was wondering if anyone has any thoughts/ideas on how to achieve this?

i was thinking about a small 12v actuator type of setup?  can they be set up to open and close quickly?  i am not that familiar with actuators...

remote operation is also important...

the door frame will just be pine and the door will probably be just a sheet of ply...

any thoughts or suggestions would be greatly appreciated.

[edz]

12V Solenoid on a push rod maybe at the top of the door or a two way pneumatic ram .could run from an air tank so no need for a running aircompressor during the show .  Maybe for a cheapie DIY air ram  get an old gas strut thats cactus drill a couple of holes, one  each end and plug in two air lines, one to extend it one to close it .  https://www.youtube.com/watch?v=NTDigvJ8pU4 . and   https://www.youtube.com/watch?v=rTPO0Xn9_K4  ..or cheapies of fleabay http://www.ebay.com.au/sch/i.html?_odkw=pneaumatic+rams&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xpneaumatic+cylinders+.TRS0&_nkw=pneaumatic+cylinders+&_sacat=0

[paceman]

i might be able to change the door operation to a sliding door config...

this might make using a pneumatic ram a bit easier to manage...

[briann532]

Thinking a bit differently and cheaply..........

Can you screw a spring to it down at ground level then close it so the spring is under tension then release with a release mechanism or catch of some sort?

[Patr80l]

Does the mechanism need to be hidden?    Wouldn't it be easier to have a person hiding off stage pulling on ropes?   I figure that's how it's usually done in amateur productions so probably you've already thought of that.   Are you over-thinking it?

[paceman]

Does the mechanism need to be hidden?    Wouldn't it be easier to have a person hiding off stage pulling on ropes?   I figure that's how it's usually done in amateur productions so probably you've already thought of that.   Are you over-thinking it?

ropes won't really work with the setup required... hence the outside-the-box ideas...

i might be overthinking it, but i am also using it as an excuse to broaden my mind a bit...

[briann532]

ropes won't really work with the setup required... hence the outside-the-box ideas...

i might be overthinking it, but i am also using it as an excuse to broaden my mind a bit...

Ok then spring loaded to open, with a solenoid on a catch. Ie solenoid moves pin to release door.
Electric activation or even remote control. 12 volt door actuator would work a treat.

(Can't close the door,  but that wasn't in the scope!!!)

[Patr80l]

Something like this might be part of the solution.
http://www.ebay.com.au/itm/12V-4CH-Channel-200M-Wireless-Remote-Control-Relay-Switch-Transceiver-Receiver-/311213086622?hash=item4875bed79e:g:YnUAAOSwAvJW-KP5

[Cruiser 105Tvan]

Ok then spring loaded to open, with a solenoid on a catch. Ie solenoid moves pin to release door.
Electric activation or even remote control. 12 volt door actuator would work a treat.

(Can't close the door,  but that wasn't in the scope!!!)

You don't even need a spring. 
With a couple of pulleys on the frame and a rope and a sufficiently heavy object you could open it.
It would just need a remote latch system to hold it closed, Locksmiths have them for secure doors.
You could try a servo in/on the door frame that puts a pin up through a loop on the door.
Or a magnetic latch, but that's gunna be costly.

[glenm64]

What about a el cheapo door closer(like on flyscreen doors) fitted on the outside, to pull it open when a catch is released?

Cheers Glen

[tracker]

What about a el cheapo door closer(like on flyscreen doors) fitted on the outside, to pull it open when a catch is released?

Cheers Glen

    I agree with Glen.....See if you can get hold of a screen door water closer....We used them some time ago to close security screen doors after you went through and I'm sure you could set it up to open rather that close....It's a simple pulley system hooked up to a weight inside a  square vertical rhs and the amount of water inside the rhs governed the speed at which the door closes or opens in this case...the square tube is about 2000mm long. I think you can still buy them at Porters mate.
                                                        Cheers Tracker.

                     PS.     These are used on sliding doors ..not hinged.....
                             

[paceman]

thanks all for the suggestions...

plenty to think about...

[macca]

I agree with patr80l when i used to build sets for shows we would just have one of the stage crew hidden in the set and he would use a rope or rod attached to the door to open and close it. Was hard to find crew that were happy to be jammed inside a piece of set for a whole act tho

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[terravista]

You could attach a fine fishing line out from the door and down a hole to under the stage area.
Fit an under floor Guinea Pig wheel with the fishing line attached to the wheel like a winch drum.
Rig a large bird cage behind the Guinea Pig cage, put  a wedge tail eagle into the cage and cover the cage.
Put a Guinea Pig on the wheel, and remove the bird cage cover when required.
If the pet shop is out of Wedge Tail Eagles, you could substitute it with a Death Adder and replace the Guinea Pig with a field mouse, but make sure the door opens easily and the wheel turns freely as the body mass of the mouse may struggle overcoming the inertia of the door.
Easy as and no tricky actuators or compressed air systems.

[paceman]

You could attach a fine fishing line out from the door and down a hole to under the stage area.
Fit an under floor Guinea Pig wheel with the fishing line attached to the wheel like a winch drum.
Rig a large bird cage behind the Guinea Pig cage, put  a wedge tail eagle into the cage and cover the cage.
Put a Guinea Pig on the wheel, and remove the bird cage cover when required.
If the pet shop is out of Wedge Tail Eagles, you could substitute it with a Death Adder and replace the Guinea Pig with a field mouse, but make sure the door opens easily and the wheel turns freely as the body mass of the mouse may struggle overcoming the inertia of the door.
Easy as and no tricky actuators or compressed air systems.

appreciate the attempt at levity, but would like to keep thread on-topic, if at all possible... 

[#jonesy]

You could attach a fine fishing line out from the door and down a hole to under the stage area.
Fit an under floor Guinea Pig wheel with the fishing line attached to the wheel like a winch drum.
Rig a large bird cage behind the Guinea Pig cage, put  a wedge tail eagle into the cage and cover the cage.
Put a Guinea Pig on the wheel, and remove the bird cage cover when required.
If the pet shop is out of Wedge Tail Eagles, you could substitute it with a Death Adder and replace the Guinea Pig with a field mouse, but make sure the door opens easily and the wheel turns freely as the body mass of the mouse may struggle overcoming the inertia of the door.
Easy as and no tricky actuators or compressed air systems.

Do you need an actuator to remove the cover off the bird cage?

Ons serious note. Could you make the door lean towards the audience so when the catch is released the weight of the door will swing itself open. The audience won't notice it is leaning towards them if the are sitting lower than the stage.

[paceman]

Ons serious note. Could you make the door lean towards the audience so when the catch is released the weight of the door will swing itself open. The audience won't notice it is leaning towards them if the are sitting lower than the stage.

possibly... might have to check that out...

[terravista]

appreciate the attempt at levity, but would like to keep thread on-topic, if at all possible... 

No sweat, but I would have thought offering a suggestion that answers your query to be very much on topic.
Reading between the lines and disregarding the obvious (eagles and snakes etc) is the possibility of using what could be a reasonably simple and cost effective fishing line. Not rope and sticks that would be visible to the audience, but depending on possible obstructions could be an easily hidden solution.

[Gunsrunner]

What about a remote central locking kit, if the door is light enough the actuators could be strong enough to open and close it, or you could use 4 actuators on the door.

[terravista]

OK, I promise, no animals this time.
What if you fitted an extension piece to the door like a shelf support bracket or even a rod, long nail or whatever to the top of the door frame so it extends out 150mm or so, tacked a strong rubber band to the top of the door and stretched it over the extension piece.
A catch or the door knob on the inside could have  a thread attached to it so it can be opened by an off stage helper. Then, when released, the rubber band tension opens the door?
The faster you want the door opened the longer the extension piece or stronger rubber band.

or

Take the spring off a rat trap. Fix one end to the door frame, open the spring up and force the door shut under pressure.
Use a latching system to hold the door closed until released.

[#jonesy]

A low tech release mechanism basically a stick on a pivot operated by a release rope. Probably the most fail safe release mechanism.
If the pull rope is looped over it can be pulled out of the way when the door is released.

The bottom pic is what terra vista suggested (I think)

Thought I better add the pic

[tk421]

Fishing line and a pulley or two. Stage hand pulls line door opens.

Simpler if the door is held in a flat. Stage hand stands hidden from audience behind the flat, on hinge side of door, and pushes really hard from behind, withdrawing hand quickly.

[Cruiser 105Tvan]

If your going to have a stage hand standing behind the flat, anchor a piece of 40x20mm timber across the rear of the door.
Make sure that the piece of timber extends past the frame and you can use that as a handle to open and close the door.
Just hang a piece of cloth/backdrop so the door operator is hidden from view. And maybe a lack of lighting behind so the door operator isn't in silhouette.
If it's not centre stage, you might even be able to operate it from the wings.
Or fit a weight and pulley to it, to close it, and open it from the side with fishing line, no catch needed.
The length of the timber will give you an advantage over the weight.
The weight can be a bottle of water, just fill it till it works, using a Bottle with a handle on it so you can hang it securely.
2 Litre fruit juice/Milk bottle would probably do it, won't need much.

[macca]

Keep it low tech as possible, high tech causes problems on show day, especially when someone forgets to hook up the battery or one of the kids pulls a wire out. Experience  speaking

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