[Revenant]

Good cylinders/actuators are pricey, and I don't want to mess with jury-rigged pneumatics (pvc, doorclosers, sprinkler popups etc)... has anyone worked with air muscles, those reinforced bladders that shorten when they inflate? They only draw up about an inch, but I've read they're pretty strong and work well for angled applications if you have your origin and insertion points planned out well.

I was wondering about their pull-power, and air consumption as compared to cylinders. I know some applications will only work with a long-draw cylinder, and the air muscles can only pull and not push... but they're incredibly simple in their design, durable, and SO much cheaper, they're like the equivalent of the sales tax on a cylinder! Any input would be appreciated, I'd really like to start playing with pneumatics and may as well start out with something I can afford right now!

 

[Sickie Ickie]

I have not heard of these. Have any more info on them? Pic? Price?

 

[Revenant]

http://www.imagesco.com/catalog/airmuscle/AirMuscle.html

There's a place I just found online... a bit more expensive than I remembered them, but the ones I saw a few years ago at half the price may have been cheeseball cheapies, too. I noticed the same place also sells those muscle-wire air valves; pair those up with air muscles and you've got a ridiculously low-weight and low-profile pneumatic unit (though if the profile isn't an issue, those washing machine valves are still a better deal for the price than the musclewire valves since you can pull them off of junked machines for free).

They're popular in industrial robotics, far cheaper than cylinders and servos. but I was wondering if anyone here used them specifically for haunting. It looks to me like the motion might be a bit jerkier than conventional actuators.

 

[1031fan]

revenant - just out of curiosity - is there any particular reason you dont want to use door closers? safety would be my number one guess - but with the right applications they actually can be very very safe-ive been using the same doorclosers for years - especially with a few precautions - now i wouldn't ever put them into a pro haunt - but i probably wouldnt put the bladder things in either - just my 2 cents - riley

 

[Doomsday Cult Leader]

They aren't popular, just new. I don't know of any industrial application that uses them.
I'm a machinery repairman at Delphi, (the worlds largest auto parts manufacturer) robots everywhere. If you need a robot in an industrial application, you need consistency, repeatability, reliability, and durability. Air muscles are small and light, but that's really about all they have going for them.
Our engineers tried using a few on some machines about two years ago. They were springier than a cylinder, weaker and nearly impossible to adjust. Pretty much on or off, no speed controlling, no cushion. They were soon replaced with small inexpensive Bimba cylinders and simple flow control valves.

For a haunt application, as long as no-one will get hurt when the rubber hose fails, they'll probably work fine. They might be a good alternative to skull mounted servos... or skeletal fingers that move individually.

But, if you need something that works predictably, every cycle, for years, tried and true wins over new and trendy.

If you do try them, keep them out of the elements. The hose will degrade faster with exposure to UV and heat.

 

[punch]

from what I've read they are pullers, and then need to be stretched out for the next pull, kinda the opposite of what an air cylinder does.

 

[HalloweenRick]

The only thing I can remember about air muscles is that's how we thought that Distortions "Breathing Ground" worked at Transworld in 2006. The ground came up, then slowly returned to normal, and re-inflated approx 30 seconds later...

 

[Doomsday Cult Leader]

Cylinders can push or pull, or stop and hold their position.

 

[Revenant]

Air muscles are strictly pullers; they're the reverse of a single-action cylinder, using a load to return them to their resting state. This is done either with a spring or, if double-action is desired, with an antagonistically paired muscle, like real muscles in an animal. They can also hold their position in a "soft stop" by simply not allowing them to deflate; naturally this wouldn't be practical in a situation requiring a hard braking action or a heavy workload to be immobilized in the actuated position.

I do stand corrected on industrial application... when I was websearching on them I saw dozens of references by robotics engineers; when I chased the links however they were mostly in robotic research and limb replacement research where a more organic muscular action was desired (that "springiness" isn't considered a liability in every application). The lighter weight and elastic materials don't stand up to the high-load stress under thousands of cycles that a cylinder will. Still, several do tout animatronics as an area where they are well suited due to the smaller loads and lighter weight requirements. Id still choose them over a home-made cylinder or reconditioned door piston; If I need industrial strength, I'll shoot the bucks on a real cylinder and not take my chances cutting corners.

 

[Doomsday Cult Leader]

Yeah, engineers love to try new toys. Then those of us who have to make it work in a real world application, must fix it so it'll actually function longer than "Well it worked on the test bench." (That's one I have heard myself, he said he ran "well over a thousand cycles." and he couldn't figure out why his machine broke down every two days. We ran 12,000 cycles a shift, 3 shifts a day. Is an hours testing really going to tell you how good your design is?
We ended up replacing his bushings with bearings, shock mounts instead of hard mounts, adding flex couplings and cyl couplings, etc... Basically 50% redesigning "his" machine. The best part was having to get his approval for the changes!)

"Too many cooks spoil the broth... too many engineers spoil the productivity of a machine that was working just fine!"
---------

I definitely think basic animatronics is a good platform for air muscles, just fine for when you need to raise an arm. Lousy, when you need to raise an arm to the exact same position, in the exact same amount of time, every time. But for a machine that doesn't interact directly with another, like an animatronic, air muscles, even home-made ones, should work well.

Speaking of home-made, I too, strongly suggest using the proper tool for the job, primarily for safety. I do however feel that an air muscle is something that can be constructed by someone with basic construction skills and an understanding of how they function.
A rigged together cylinder can easily fail and become a hazard, an air muscle failure simply results in a pop and the mechanism being lifted, falls.
Hopefully nobody designs a prop that will strike someone no matter how it fails!

1031fan, I was wondering why you wouldn't use a modified screen door closer in a professional situation, yet feel perfectly fine exposing people to them as long as they aren't paying?
The only argument I can think of that might apply, is the Russian roulette ratio. The more times you pull the trigger (or cycle the rigged up prop) the more likely the gun will fire (or cylinder will rupture).
But sometimes the gun goes off after only a couple tries...
Just because something worked "well over a thousand" times, doesn't mean it will work forever.

I'm not picking on you personally, you just happened to be the one who said the same thing I've heard many say before. Yet I haven't heard a good answer as to why people are willing to expose their friends, family, and neighbors to something that they wouldn't put in front of a paying stranger.

 

[Sickie Ickie]

Doomsday, I understand perfectly where you are coming from. To state it simply, you believe that pro cylinders are made specifically for endurance and are less likely to fail over a number of given tries- therefore safer.

On the other side of things, there are people who believe that homemade cylinders are reliable provided they don't exceed max pressure- therefore cheaper and still reliable.

I believe that many people who use homemade cylinders have the idea that pro haunts must have pro-parts instead of homemade in order to make a prop look as professional as possible.

However you do raise an interesting question. If people who make homemade cylinders consider them reliable, why not use them in pro haunts too considering the cylinder is never seen?

*careful folks, think carefully before writing. We don't want this friendly forum to turn into a heated argument. Remember that people feel passionately on both sides.

**moderator, feel free to move this discussion to its own thread.

 

[gadget-evilusions]

I saw a really interesting display made by festo pneumatics using air muscles when I went to automation fair this past october ( i do industrial automation for a living). I have yet to come up with an application where you would want to replace a cylinder with an air muscle in a haunt application. They are mostly used when you need a very fast small movement. In haunt applications you mostly need slower moving large movements. Slow and fast being relative terms here. I guess this is one more thing to add to my pneumatics 101 class I will be giving at Hauntcon, Ironstock, and MHC this year.

I will try to find the video I took of them in action and post a link.

 

[ScareFX]

Doomsday, I understand perfectly where you are coming from. To state it simply, you believe that pro cylinders are made specifically for endurance and are less likely to fail over a number of given tries- therefore safer.

On the other side of things, there are people who believe that homemade cylinders are reliable provided they don't exceed max pressure- therefore cheaper and still reliable.

I believe that many people who use homemade cylinders have the idea that pro haunts must have pro-parts instead of homemade in order to make a prop look as professional as possible.

However you do raise an interesting question. If people who make homemade cylinders consider them reliable, why not use them in pro haunts too considering the cylinder is never seen?

*careful folks, think carefully before writing. We don't want this friendly forum to turn into a heated argument. Remember that people feel passionately on both sides.

**moderator, feel free to move this discussion to its own thread.

I'm going to leave the posts in this thread for right now since the discussion is intermixed.

But please stay on topic. If you want to discuss homemade verses professional components, please start a new thread. And please mind the forum rules.

 

[Doomsday Cult Leader]

Gadget: Cool, I'd love to see air muscles in an application that actually works.
"I have yet to come up with an application where you would want to replace a cylinder with an air muscle in a haunt application."
I hear ya bro, I hear ya! Just in case I didn't quite get my opinion of them across... I think there may be a good use for them, I don't want to be the guy who has to make it work though!

(For my next trick, I will converge the home-made & air muscle topics...)

It may be cheaper to make your own air muscle pullers, I don't know as I have no desire to use them and so I haven't priced them. But they are really quite simple, and even though I am a "Safety Nazi", I believe there is little inherent danger in them.
So, if someone were interested in giving them a try, I think home-built might be a viable option.

(Hey Rocky! Watch me pull a rabbit out of my hat!)