Thread: pnuematic clown prop help!

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okay! ive set my pneumatic cylinder up tested it and it works very well. Its time to start setting it up for my frame behind the prop here it my plan!

I have a 2 by 4 whick the back part of the cylinder will go to... there will be a wood plate for the front of the cylinder stroke to attach to the the clown. then it will be bsed withh wooden legged frame behond the clown body so its not visible. My cylinder has a 4'' stroke. I need to get the nose of tghe cylinder to attach to the prop part of thr back of thre clown. this prop will be a pop out prop with the cylinder horizantally.

does anyone have any pics or videos that vould give me a better idea!
Thanks,
Chris

The clown is going to jump out correct?

So are you mounting the clown on a hinge at the feet?

How far do you want the clown to jump forward. If you mount the clown to a board that is hinged at the bottom, then depending on where vertically you mount the cylinder will govern how far the face of the clown comes forward. Of course the further down you mount the cylinder the stronger it will need to be.

Maybe use bolts as opposed to wood screws. Wood compresses easily, so good idea to use fender washers to spread the load.

well i only have a 4'' stroke cylinder and i was hoping to find a way to make the prop pop out further.. at this point the prop is on a wooden band i wasd going to put the cylinder horizantally to the prop in the back of the neck on no angle just straight aross i wanted it to kind of look down becuase it is 6 ft tall and it already manually has a tilt when you hold him upstraight and let him go he moves foward because of the uneven weight distribution so makiong it pnuematic would be great!
please help!

you can use a 4-bar linkage mechanism... see this page, and download the 4-bar simulator. This will allow you to experiment with lengths and angles before you assemble..

http://www.boopack.com/software.html

Ctarpey,

If the clown is 6 ft tall, you can get more movement if.

1. The clown is mounted on a vertical board that extends to the feet. There you can use a heavy gate hinge to mount the unit to a floor plate. You will need to either secure this plate to the ground or weigh it down with concrete blocks. The plate should be large enough to easily hold the prop upright, and when th prop swings forward to say 45 degrees. Keep in mind that momentum will be your enemy here., You don't want the prop falling on people. I would make sure that the people can not get too close.

2. You can mount your cylinder further down, but the further down you place it, the stronger it will need to be. I hope you have a double cylinder. You need to return the prop to an upright position. You can counter weigh the prop by using a cable attached to the back of the prop and loop it over a small pulley with a weight attached. The higher you mount your counter weight the better and less weight required.

3. So lets say you mount your cylinder 4 " from the base. Your prop would come forward to a 45 degree angle. At 12 " it would come forward about 30 degrees. At 24 " maybe 15 degrees. So you can see that just using the cylinder directly may not achive your goal.

Now the 4 bar linkage is the way to go, but I am not sure if you are equipped to produce such an item. But you might be able to use a simple slide lever concept. On the back of your prop on the vertical board you mount a piece of drawer guide. Just go to Home Depot and get the kind that is white steel channel. Not the ball bearing kind. You mount one channel on the back of the prop. Say mid back. Now you will need a lever that you can mount one of the drawer guide rollers too. That should be steel or thick aluminum. In your vertical cylinder mount board, you will cut a slot. This should be at mid back level. I advise you use a 4X4 for this board, and support it at the base with at least three braces. One on each side and a larger one toward the rear. The slot is to create a pivot point for the lever. The cylinder will be mounted on the back of the 4X4 below the slot. A hole will be drilled in the lever. You can drill a few to get different strokes. So the lever with the drawer guide roller will be nearly vertical with the roler at the top of the guide mounted to the back of the prop. The lever will come through the slot and be held there with a bolt through the slot. If you want to get fancy you can get a nylon bearing to fit in the hole of the lever and the correct id for the bolt. The other end of the lever will be attached to your cylinder and the cylinder will be fully closed. Make sure that the full stroke does not cause the lever to become 90 degree's to the prop. You want some angle to remain at full extension. What you are doing is increasing the amount of movement via geometry. If you have 6 " of the lever sticking out the back and 12" sticking out the front to the prop, then you will double the length of your stroke. 6" and 18" and you triple the amount of movement. Just keep in mind that the more extension, the higher the load, so be prepared to counter weigh the prop.

As the other member mentioned. The 4 bar link is the way to do this properly, but you may find this idea a bit more acceptable. Just make sure you make your mounts and base and braces strong. Always over engineer when it comes to pneumatics.

you wouldnt happen to have a video of the 4 bar linkage or how is hould mount my cylinder like u suggested... its hard taking it all in without images or videos

I wish I could do pneumatics. My father-in-law works for a pneumatics company in Michigan for crying out loud. Any air-heads in L.A. that want to join up to build some stuff, hit me up.

Like this?

YouTube - IMG 0029

Not usually a good idea to suspend props on a cylinder. A very light prop perhaps, but pneumatic cylinders are not designed to take side loads. Ctarpey's prop is 6 ft in height. I do not think this is a viable solution for his needs. Not to mention that he only has a 4" throw cylinder. Jumping out 4" will not be too impressive. IMHO.

Here is a video that can give you a good idea. Just look at the bottom left and think about attaching your cylinder there. Disregard the full rotation. This linkage would work with a motor as well. But I think you will see that a short distance of movement in the linkage in the lower left corner results in a big movement at the bar end on the upper right. There are all kinds of examples to look at. Just google 4 bar linkage. You will see more than enough.

YouTube - straight line linkage


Here is another one.

YouTube - Four bar mechanism