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Discussion Starter #1
OK guys I am a newbie here at propbuilding but have a lot of plans for my next year haunt and am trying to start early, though I need help with some basic concepts and ideas as the topics of controllers, valves and solenoids get’s confusing, or for me anyway. To start with I will build a MIB with the rocking motion with the cylinders at the bottom and have 2 pneumatic cylinders at the bottom firing down, I have figured out the basic concepts of design and construction but need more specifics and will try and ask my questions in order.

1. What type cylinders are recommended as for size and stroke and would single action ones not work OK thus making for an easier design, something in the area of 1 ½” bore and 3” stroke about right?

2. On to manifolds, I am assuming I need a manifold block that has one air input and an output for each line into the solenoid for the cylinder or could I just go straight into one multi output solenoid which leads to question 3 below?

3. Regarding solenoids, if I were running 2 cylinders each with 2 air lines attached (if using DA cylinders) it would need to have one input for the main air and 4 switched outputs?

4. If 3 is true what solenoids are recommended, and do they have 4 wires coming from them that activate which valves open?

5. If I added another cylinder to open the lid and it were a DA cylinder then I would need a solenoid with 6 outputs, is this correct?

6. Now on to controllers to run all of this, I already purchased the EFX-TEK Prop 1 controller, and if I understand correctly this will control 7 different outputs via DC out, and if I needed AC then I would have to use a relay. So in the case above if I used 6 outputs on 3 cylinders I would then have one left for fog, lights or sound? Also will this controller work OK or is there something better that may be less expensive and/or easier to use?

Thanks in advance for any input, I am trying to make sense of all this stuff and I have been lurking here for a couple months now and appreciate all the experience, ideas and help that all you folks offer.
 

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Let me try to answer some of your questions:

1. Single action cylinders should work fine. The air entering the cylinder extends the rod, and releasing the pressure allows gravity to retract the rod. The stroke does not need to be very long; I had great success with only 1" stroke. A longer stroke would take more time to fully extend, and it's usually the quick movement rather than the range of motion that creates the startling effect from this kind of prop. 1 1/2 inch bore should be sufficient as long as your crate is not too heavy ... a larger bore will generate more thrust, at the expense of needing more air. My 3 foot by 3 foot crate was made out of pallet wood, and it got VERY heavy when it became soaked with rain.

2. For your application the "manifold" need only be a "Tee" or "Y" connector in the supply line. One port connects to your compressor, the other two connect to the "in" ports on your valves. Which leads to #3...

3. I would use two 3-way solenoid valves for this application, one for each cylinder. That way the cylinders can be activated independently of each other, allowing a more random movement which can be more realistic. Clippard makes 12V DC solenoid valves that are ideal for this kind of stuff. When activated, they allow air to pass from the input port to the output port, extending the cylinder. When de-activated, the input port is shut off and the output port is directed to an exhaust port. This releases the pressure from the cylinder, and gravity pushing the rod back in forces air out of the cylinder, back into the output port of the valve, and out through the exhaust port.

4. I think I covered part of this in #3. Each valve has two wires; connect one wire to a 12V DC power source, and connect the other one to an "active-low" or "ground-side" control signal. Do the same for the other valve, using a different control signal. See #6.

5. Adding one more cylinder would require one more "tee" in the supply line to provide the source, one more 3-way valve (assuming gravity will be used to close the lid when you release pressure), and one more output signal from whatever controller you use.

6. The Prop-1 controller from EFX-TEK is ideal for this application. It has 8 I/O pins available, so you could have a motion detector trigger input, three outputs for your three valves (2 "feet" and 1 lid), plus other outputs for lights, fog, and sound. EFX-TEX sells a solid state relay module for AC control, although you could wire your own mechanical relay and activate it exactly the same as your air valves. EFX-TEX sells an amplified sound module, too. Jon will even write your program for you if you want. (BTW, I am in no way associated with EFX-TEK other than as a satisfied customer. They have superb customer support).

Hope this helps!
 

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Discussion Starter #3
skoker your reply helps greatly, thanks for the input and the clear and concise answers. As for whether single action or dual action cylinders, while I do understand the difference now, I still wonder why do most folks with this type of prop us DA cylinders when they are not needed and don't add anything to the effect?
 

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skoker your reply helps greatly, thanks for the input and the clear and concise answers. As for whether single action or dual action cylinders, while I do understand the difference now, I still wonder why do most folks with this type of prop us DA cylinders when they are not needed and don't add anything to the effect?
The double acting just leaves you with a few more options like being able to have a powered stroke in each direction, or possibly installing a speed controller in the second port to slow down your movements for more control.

In some cases double acting cylinders are even cheaper than single acting. :)
 

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Discussion Starter #5
Yes I have found that DA cylinders can be cheaper, now just to find a few with 1 1/2" bore and around 2-3" stroke for cheap. Again thanks for the info.
 

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Here is some info I wrote some time ago

Hey robisc,

Here are some slides I put together a few years ago (maybe someday I'll write a book!) This is some of the information that I learned when I got into haunting and have streamlined over the years. I had this posted before on Halloween Forum, but I think the links went dead or something, for whatever reason they are not showing up on those posts anymore. So I'll repost these here for you to look through... btw this is 'solenoid primer part 1'. I'll post more below...







 

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More of the same

Here is part 2 of the solenoid primer... if these don't all fit in this post I'll put the last two in the next post











 

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Control Primer

I can't actually remember if I ever finished this one, we'll see when we get to the bottom! This is the control primer...



















 

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last couple slides

These are the last part of the control primer, I hope many of you can use this info, but of course I am not responsible! Let me know what you think of the material...











 

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Discussion Starter #11
SkeletalRemains this is great and obviously you have spent a great deal of time on this, it is a big help to me and I'm sure to others as well. Thanks!
 

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Glad this helps you! One of these days I might just finish the rest of these pages!
 

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Thanks for the info SkeletalRemains!!!

I'm tired of relying on people to pull strings and run props so I'm looking for a "Dummy's Guide to Building a Complete Pneumatic Prop." I'm trying my first shot at a simple pneumatic device - a flailing dismembered arm. I am NOT an engineer or a mechanically inclined person at all. I can build static structures and I've been able to do simple wiring like LEDs and I thought I'd step it up this year. I found the slides on simple pneumatics and I understand the discussion and how the props work, but there are a few confusing areas for me:

1. Solenoids and manifolds - it seems that some are 'combined' units (both solenoid and manifold) and I don't know how to tell the difference and the sellers on EBAY are typically not very helpful. Is there an easy way to tell? i.e. if they tell me it's an electric solenoid with 3 ports, do I assume it's a solenoid/manifold 3-way valve? How can I tell? Are there certain manufacturers I should look for? Is there a version that just plugs into wall power or do I need a separate power source?

2. Triggers - I havent found a good electrical diagram or discussion on how to wire in the trigger mechanism (my idea was a garage door sensor for a trigger). Does anyone have a diagram or two on that or can you describe it well?

3. Pneumatic cylinders - I understand the single Vs. dual action and the mechanics, but as far as purchasing one long distance (i.e. EBAY) I am hesitant to pull the trigger since I am not sure exactly what to look for beyond the action and stroke. Is there anything magical about one manufacturer or another? Is there a minimum bore/stroke or ratio of the two? Do I need to be concerned with how it's mounted or should I look for a particular style?

4. Compatibility - My final concern is about combining all the elements. Provided that I make sure the device is rated voltage is compatable, are all these parts universally connectable? Is there a standard tubing/connection diameter or do I need to also check that? Is it simpler to find adapters?

Thanks for your help!!!

-E
 
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