# Barrel popup - my first pneumatic!



## GPSaxophone

I have been wanting to get into pneumatics for quite some time, but never quite got around to it. This year I decided to give it a shot and it was easier than I expected.

I used the basic design I found at Snyder Central and made a couple of minor changes due to parts availability. I also added a couple of 90° elbows to save space at the bottom, just in case I move it to a smaller barrel eventually. Because of this, I eliminated the flexible riser and used a cut-off riser instead.

I wasn't quite sure how to attach a head/skull to the popup tube. I ended up using a 7/16" wooden dowel which almost fit perfectly. I added a strip of electrical tape to one side (wrapping the tape around it made it too thick). The dowel is attached with more electrical tape, using enough around the end to keep 1/2" or so of the tube from retracting into the housing. This seems secure enough to make it through several hours on Halloween.

The 20V power supply I was going to use didn't like being connected to the solenoid - it needed to be unplugged in order to reset. I connected it to a computer power supply and it worked well even at 12V. I thought I had a stash of NO switches, but it looks like I'll need to run over to Radio Shack tomorrow to pick some up. My remote switch wiring is cat5 since I have a lot of that around for my Christmas light display. I have a long enough cable to activate the popup from inside the house.

This prop isn't quite complete, but I don't think it's bad for a 1/2 day's work. I rebuilt my kicking legs this morning and spent the afternoon on this. I plan on adding a biohazard/nuclear label and stenciling "Toxic waste" on it. I have a couple more barrels to put next to it that will be labeled the same. One will be laying on its side and if I can get it done, I'll have a crawling zombie torso in front of it. I also bought some Great Stuff to go around the rim. The skull will be wearing a hood (and be secured better) and I'll have some green lights inside the barrel so it will glow. I'll post more pics when I finish, but here's what I have so far:


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## DarkLore

I think it's great that you are delving into pneumatics. Be very careful about the amount of pressure you use.

I mean no disrepect to your prop, but I agree with Joker's previous posting regarding safety. Parts that aren't intended for pneumatic use, shouldn't be used for pneumatic actions. Pvc doesn't have the same specifications for pressure and its weakens with time and other factors such as UV exposure.


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## GPSaxophone

Thanks for the link to Joker's post. I agree that props need to be built safely, but I do have a question about using PVC. Sprinkler systems are designed to work on 45-70 psi. Why wouldn't it be safe to use air at the same pressure?


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## HalloweenRick

I think it has something to do with the quick burst of air that weakens the PVC. I think the funny thing is that almost all of us got started using PVC cylinders or storm door closers, and then graduated on to pneumatic cylinders. My education began when my PVC cylinder burst- luckily 2 weeks before halloween and I replaced it with a SMC cylinder from Evilusions. Now when I say it "burst", I mean it shattered like a hand grenade went off and sent PVC pieces flying everywhere- I was extremely lucky I was not near the cylinder and was near the air compressor fiddling with it instead. I also thank God my 2 year old was not out in the garage with me at that time. So please consider switching this out with a pneumatic cylinder for safety's sake- If not from Evilusions or another vendor, you can always find a cheap lot of them on Ebay. Please ask here on the forum or drop a line to Evilusions if you need help.


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## GPSaxophone

I just had a thought...I could take the air fitting off and connect this to my faucet. The prop would be water powered instead of air powered and still use the same control mechanism. This would eliminate the noise from the air compressor as well. 

Thoughts?


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## DarkLore

GPSaxophone said:


> I just had a thought...I could take the air fitting off and connect this to my faucet. The prop would be water powered instead of air powered and still use the same control mechanism. This would eliminate the noise from the air compressor as well.
> 
> Thoughts?


I would think that's a bad idea. Not just because of electrical hazards and leaks. Ever see a little trick or treater named Murphy running around your area? Btw...how would you exhaust water?


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## GPSaxophone

The same way I exhaust the air...the black solenoid in the picture above. With air, I don't need a drain pipe, but with water I would. Fortunately, there would be a very small amount of water used each time it wouldn't pool up. 

Just a thought. I'm going to keep it as is for Sunday night and build something better next year.


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## dna1990

Life is mitigated risks. So you have the barrel to contain the shrapnel if a burst occurs, if you can add some covering near top leaving just an opening for piston or head, even better.

Add maybe a safety wire to the piston itself to guard against blow-off.

Tune PSI with a regulator to have the absolute min needed...if that skull is the only lightweight prop, it should only need a few pounds.

Place prop somewhere other than right next to the main walkway for your TOT...and call it good.

Don't leave the unit 'open' for any longer than needed. Meaning don't trigger the piston and leave it 'up' for 30 seconds before discharging and letting it down. Up for just a second (or less).

For startles like these, an loud and sudden audio is more important than raw motion.


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## GPSaxophone

It's triggered by hand, and only takes a second to engage. I can either open the second solenoid to release it and make it pop back down fast, or the air will bleed off after 15-20 seconds on its own.

I do have a regulator so it doesn't receive the full power of the air tank.

The prop is out of arm's reach from the walkway, and since it's activated by hand, I'll have my eye on where kids are when I activate it to be sure they aren't too close.


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## wheussmann

the burst rating on pvc is based on the surface area of water. and energy stored in water. there is a long math formula for this, and don't want to bore you to sleep so I will use laymens terms

air contain approx 6 times the energy force of water under the same presure. so yes pvc will work for a given time due to the bonds in the pVC, but if there is one flaw or nick in the Pvc you can call that spot a fuse, as it will burst.

pvc will work for a short life, if you want to stick with Pvc and run say 60 PSI you will need to have PVC rated to handle ruffly 360 psi. for that you will need a schedule 60 pvc. and the cost is starting to fringe using steel. they do make a product that is light weight like pvc and has great quick release fittings for more versatility, http://www.garage-pak.com/

I am not trying to shy you away from PVC as I am jumping into that realm as well (tired of motors burning) but I work with air systems in my field and I would suggest to shy away from pvc.


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## GPSaxophone

The prop worked great on Halloween. I managed to scare (or at least startle) several people. As expected, the middle-schoolers tried to make it activate again by waving their arms and walking away, then towards it again. I kept watch, and activated it once they got far enough away. They never figured it out. 

Now that I have an idea of how pneumatics work, I'll make next year better with equipment designed for that purpose. Thanks for the tips!


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## wheussmann

glad it went well. it is a cool looking prop. good luck with it next year.


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## gadget-evilusions

GPSaxophone said:


> Now that I have an idea of how pneumatics work, I'll make next year better with equipment designed for that purpose. Thanks for the tips!


And you have 11 months to find the cylinders you need off of ebay, or save up and buy new.


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## bfjou812

gadget-evilusions said:


> And you have 11 months to find the cylinders you need off of ebay, or save up and buy new.


And they are really not all that expensive.................


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## RLukard

I attached my skull to the cylinder using a thread reducer. The thread reducer coupled to a threaded lamp nipple. But as for air pressure, I read that it was between 40 and 60 PSI for a gravejumper/popper


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## ouizul1

DarkLore said:


> I would think that's a bad idea. Not just because of electrical hazards and leaks. Ever see a little trick or treater named Murphy running around your area? Btw...how would you exhaust water?


If you have a pool, a water based system works great. It can be powered through a sprinkler system control valve from any garden hose. And the exhaust water just vents into the pool. Did this once in an above ground pool, attaching the pop-up to the pool ladder so the creature raised up out of the pool like it was climbing out over the ladder.


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## X-Treme Torment

I totally agree wheussmann. A nearby haunt built 3 air cannons out of pvc and used a sprinkler valve for the solenoid and about the third day (hundreds of groups later) the air chamber made out of pvc exploded cutting a hole right through the 1/2 inch thick wooden wall and shoot splinters all over the group. Luckily no one got hurt. So I think saving a couple bucks on pvc is not worth a lawsuit and people getting hurt.


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