Newbie to air cyclinders need help, anyone have tips??

Im sure someone will shoot me for suggesting this, but I was in the same boat as you a month before halloween and the way I became comfortable with how air props worked was by hacking a couple together with PVC, Door closers and sprinkler valves.

They didnt work like I was hoping, but the amount I learned was priceless and now that I figured it out with a small amount of trial and error, im now decommisioning the two props I built and am going with welded steel and commercial valves and cylinders.

You can either start the way most everyone here has with non-commercial parts and work from there (My recommendation) or you can grab a cheap bimba cylinder from ebay, I would suggest at least a 4-6'' stroke (how far it moves) and a 1 1/4'' diameter rod, a decent air valve (someone else will have to suggest one becuase im in the same boat) but I would still suggest using 1 1/4'' PVC that way you can easily adjust the linkage to get the desired effect.

Here is a quick pneumatic for beginners
http://www.wickedstone.com

**Looks like his website is down, if you would like the .ppf of the file, PM me and ill email it to you.

***I also have a couple of easy 4-bar linkage diagrams that I can email you that will help, just shoot me a PM with your email address if your interested.

Here are a few links I dug up.

http://www.scaryguys.com/slinger.htm
http://www.halloweenpropmaster.com/coffin_sit_up.htm
http://www.halloweenfear.com/Manifold.html
http://www.hauntedillinois.com/pneumatic.php
http://www.virtualplacebo.com/halloween/props/grave_jumper/index.htm

Here is a 4bar program that you can use to help design your linkage, you will have to play around with it to familiarize youself, but once you get the hang of the software, its a great thing.
http://www.boopack.com/software.html

You can easily design your linkage around your cylinder, the only problem would be if you didnt have enough stroke. (and even then, you can still solve it with alittle work)

I suck with trying to explain things, so bear with me here.

For example, you can get the same amount of action in a body slinger (distance your body is slung from rest position) using a 6'' stroke or a 10'' stroke, the placement of the cylinder (further up/down the linkage, depending on which way your looking at it) or length of linkage is what matters.

Dont worry about getting the wrong cylinder, try and stay in the 6'' or higher department unless your wanting to use the cylinder for small movement.

on the body slinger I built, if I position the same 6'' stroke cylinder at different positions on my linkage, I can get more or less action from it.

If I attach my cylinder 6'' from the back of the frame, it wont move as far as if I placed the cylinder 4'' from the back of the frame, but becuase its lifting more, I would need to increase the amount of PSI going to the cylinder.

If I was stuck using a long stroke cylinder, I would place it as far down the linkage to get the desired action (Lifting less=less PSI), if I was stuck with a small stroke cylinder, I would want to put it as close to the fram as possible for maximum action possible.(Lifting more=Lots of PSI)

Hope this helps alittle, let me know if anything isnt clear

Let me know if this helps.








I used those metal hose clamps in conjunction with the hardware that comes with the door closers, with alittle modification so that I can adjust the position of the cylinder on the bottom linkage, thus adjusting the throw of the prop.

I will take some pics this weekend and post them up, everything is in storage and it will take that long to pull it out :ninja:

A word of caution, I had issues with my valve and I used the same exact webpage that you have listed.. if you look at how the pictures show how to put it together (note the flow direction of the valve) and then if you look at one that propmaster allready built (in one of the movies) if you look close, you will see that his valve is put together backwards from how that picture shows..

I had a terrible time with mine, but I havent tried to take it apart and reverse the orbit valve to see if that makes a difference.

Alot of people here have built these with great results, becuase of all the issues I had, im thinking I have it backwards, so you will want to try and experiment alittle with it.

Id allmost suggest getting bimba cylinders from eBay, I ended up buying a 1/8? tap and handle to thread the door closer, which was around 6.00-8.00 and with all the brass fittings I used, I think I would have been better off buying a commercial cylinder, as long as you take your time, you will find one for as much or even lower than what it might cost you to build your own, in either case, ill take pictures of everything I have for you and post them in this thread this weekend.

**

I wanted to add on the commercial cylinders, if you have a heavy prop, you will want to use all commercial parts (cylinder/valve) since I would be very weary of putting more than 60-70psi through sprinkler parts, I have done it before, but it scared me to death to keep it up, mabey someone here can add a comment on maximum psi for DIY air props.

I want to buy a mig welder this year and start building prop frames out of steel so I will have to go the commercial route, I cant see a door closer and sprinkler valve lifting anything this heavy.