3 Axis Pneumatic Arm

3 Axis arms

This will show details and information on how I built the 3 axis arms used in my haunt over the years. Including a little info for the versions that came before and when its finished it will also provide some information for the new design I am currently working on.

What you will need:
1. 2 large slide hinges of an old door
2. 2 caster wheels with the wheel removed
3. 6 pneumatic pistons with 2″ stroke and valves to run it all
4. Assorted nuts and bolts, Lock nuts are needed with all the motion
5. Hose to hook everything up
6. Drill, Saws all, socket set, Chain breaker
7. Some small bike chain

The first time I built these arms I started with just one arm with two pistons and very limited motion. Each year since they have undergone a complete rebuild, Each time adding more pistons, better movement with a wider range of motion.  As of the last version there are two arms with three axis movement using six pneumatic pistons. I will provide details on how I built the third version.

I started on this design last Halloween, and managed to get a 2 axis set working for the season, with the extra time I decided to add the 3rd axis. The design is based on a caster wheel, This allow the lifting a twisting motion from a simple design. The first step is cutting the wheel out of the caster, I did this with a saw to cut thought the pin. This will leave you with the caster frame a few more holes will be needed to add the necessary hardware. I drilled a small hole at the top of the caster to attach a piece of bike chain to pull it back raising the arm. This makes adding the lifting motion easier. The other end of the bike chain is attached to a 2″ pneumatic piston That will pull the chain causing the caster to rotate, This piston is mounted directly to frame and is extended when the arm is down. You need to drill another hole in the caster that will be for attaching the piston that will move the arm out. This will attach about half way down the arm and to the back of the caster, when the piston is activated it will push the arm away from the frame. The Arm is mounted to the caster using the existing hole from where the wheel was removed and a hole drilled thought the top of the upper steel the arm is made of. A bolt if installed and locked in place with a locking nut.
The Last piston that will be installed is for the elbow, you mount one end of the piston to the lower arm, and then the other half to the upper arm, to avoid and binding issues, I cut 2 small metal brackets, to move the piston away from the arm. These just bolt to both sides of the arm and the piston gets bolted in the middle. This gives it the space it needs to move with out hitting anything.

Test Runs:

Changes I hope to achieve in the next version:
Add Air speed regulators for smooth motion
Better design for the shoulder
Add hands with individual finger movement
Add polycarbonate form to the arms to give them shape and protect against binding

Any questions or comments email: HauntHacker@outlook.com