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Home Made Pneumatic Cylinder
By Scott Nicholson

 

So you need a powerful, long-throw, pneumatic cylinder. Your budget, however, cannot handle the 'off the self' price? Why not build your own? This not as difficult as it sounds, the only hard part about making a cylinder from scratch, was coming up with gasket to use between the air chamber and the piston.

You can make a washer yourself out of leather or sheet rubber, however, something a little more heavy duty, that you could buy ready made would be much easier. Several yeas ago, while rummaging through my miscellaneous parts supply, I came across the perfect solution to this problem, in the form of a washing machine drain hose adapter, and used it, along with some plastic pipe and fittings to build my own pneumatic cylinder.

This was no average cylinder either this baby was powerful! It can be made any length desired and will lift just about anything. The process is extremely simple and the parts required are very inexpensive.

Material list:

  • 1 - 2" PVC SCH40 280 PSI water pipe. (White) 8" longer than the desired throw.
  • 1 - 3/4" PVC SCH40 480 PSI water pipe. (White) 6" longer than the desired throw
  • 2 - 2" PVC end caps
  • 1 - 3/4" PVC end cap
  • 1 - 1 1/2" PVC coupling
  • 1 - 3/8" x 3" brass nipple
  • 1 - Whirlpool washing machine drain hose adapter. (Part number FSP 384496)
  • 1 - Washing machine solenoid valve
  • 2 - 1/2" Long pan head screws
  • Power cord with switch
  • PVC primer and cement
  • Enough washing machine hose (to connect from air source to valve to cylinder)
  • Compressed air source (compressor)

 

Optional:

  • Pneumatic relief valve.
  • Pneumatic metering valve.

 

Assembly:

Once you have collected all of the parts, drill a 7/8" hole in the dead center of one 2" PVC end cap. Be sure that the 3/4" PVC pipe will slide freely through the hole. Then drill four 1/8" holes symmetrically through the end cap. These will let air in and out when the ram is activated.

Fit the modified end cap over one end of the 2" PVC pipe, which becomes the cylinder. Using the two 1Ú2" long screws, secure the cap onto the pipe. A 1/8" penetration into the cylinder is acceptable. Cut the length of the cylinder (2" PVC pipe) about 8" longer than the final desired movement or throw.

Remove the attaching clamp from the Whirlpool direct drive washing machine drain hose adapter. This is a bell shaped piece of rubber and the part number is stamped on the bottom of the large end. Slide this rubber piece over one end of the 3/4" PVC with the large end facing away from the pipe. This now becomes the piston. Position the drain hose adapter so that the rubber bell shaped end extends slightly beyond the end of the PVC. This will provide a cushion when the piston retracts. Two turns of electrical tape from the small side of the adapter to the pipe will hold it in place. Slide the end of the 3/4" PVC into the cylinder and through the hole in the end cap. Temporarily place the 1 1/2 coupling in the open end of the cylinder and close it with the end cap. Check the 3/4" PVC piston for length and cut it if necessary. A couple of inches should be exposed when the assembly is in the retracted position. Be sure there is enough length to attach your prop to the piston, then glue the 3/4" end cap on the end of the 3/4" PVC piston.

To keep the gasket out of the way of the air inlet, cut the 1 1/2" PVC coupling in half at the seam and insert it into the end of the 2" pipe. Some trimming of the coupling may be required. Once you are satisfied with the fit, secure the coupling with PVC glue. Drill and tap a 3/8" hole in the 2" PVC at the base to accept the 3" nipple. Be sure you drill all the way through the 2" PVC and the 1 1/2" coupling. Remove all plastic shavings from inside the cylinder, and test fit everything one more time, before gluing the bottom 2" end cap onto the cylinder.

Run a hose from your compressed air source, to the washing machine solenoid valve, and then another hose from the valve to the 3/8" nipple on the cylinder assembly. Be sure the compressed air is regulated, and set at 30-40 psi. This should be plenty to move even the largest prop. Higher pressures can be dangerous and should be avoided.

When power is applied to the solenoid valve, it opens filling the cylinder with air and pushing the piston outward. When power is removed from the solenoid, the piston is allowed to retract. When used in an upright or vertical position, gravity and the weight of the prop should be enough to retract the piston. In other positions, attach springs from the cap on the piston to the body of the cylinder, to retract the piston. Secure the cylinder assembly to something solid and attach the prop or whatever you desire to move to the end of the piston.

And then, lie in wait for your first victim.

 

Carl Chetta is the owner of Mid-Island Appliance in Babylon, New York. As a Haunted Hobbyist, he has created several unique "pop-up" scares, and can be reached via Email at: cchetta@suffolk.lib.ny.us

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