MID Control WAV Control

PVC PNEUMATIC CYLINDER
(c) By: Carl Chetta 1997
Text written by: Larry Lund

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This is no ordinary PVC pneumatic cylinder, this baby is powerful! It can be made any length desired and will lift just about anything. The secret is a readily available ram washer (Whirlpool direct drive washing machine drain hose adapter) that really works great. [Adapter] It is extremely simple and very inexpensive to make. It also can be made to any length desired.

Carl Chetta, being the owner of "Mid-Island Appliance" found this beauty while rummaging through his parts supply. He is always looking for something that he could use for Halloween.

Material list:

Optional:

  • Relief valve.
  • Metering valve.

Directions:

  • Drill a hole in one of the 2" PVC end caps so that the 3/4" PVC ram will fit inside it. The piston (3/4" PVC) or ram will slide through this.
  • Glue the 2" cap with the hole in it to the 2" PVC pipe. Better yet, use a couple of small screws through the side of the end cap and into the cylinder wall to secure it. This will allow it to be taken apart if something goes wrong.
  • Once the 2" PVC cap is secured to the top of the cylinder, drill 4 1/8" holes symetricly through the top to let air out and in when the ram is activated. [Cap]
  • Cut the 2" PVC to the proper length needed for your effect.
  • After removing the attaching clamp from the drain hose adapter, attach this special rubber fitting (Whirlpool direct drive washing machine drain hose adapter) over the 3/4" PVC with the large side down. Just wrap 2 turns of electrical tape to the small side of the fitting and the PVC pipe to hold it on. I found that the adapter had a tendency to slip so I used 2 very small stainless pipe clamps attached together and tightened on the small end of the bell. You must use small clamps so it does not hit the sidewalls.
  • Slide the 3/4" PVC into the 2" PVC from the bottom and temporarily put the 1 1/2 coupling and the 2" end cap on the bottom of the 2" cylinder. Cut the 3/4" PVC to the proper length so that a couple of inches will be exposed when the ram is fully closed inside the 2" PVC. Glue the 3/4" end cap on the 3/4" PVC. This will complete the piston. [Ram Top]
  • Once you are satisfied with the fit, insert the 1 1/2" PVC coupling into the base of the 2 inch pipe and secure with PVC glue. This stops the ram bushing from being in the way of the air inlet. Some trimming of the coupling may be required, I just cut one in half at the seam and it fit nicely.
  • Test fit everything before gluing the 2" end cap on. The 3/4" piston should extend through the 2" cylinder enough so that your working end has something to connect to. Once you are satisfied, glue the 2" end cap on the bottom.
  • Drill and thread the 2" PVC at the base to accept the 3/8" x 3" nipple. You will be drilling through the 2" PVC and the 1 1/2" coupling. This is where the air comes in.

Notes:

If you attach the drain hose adapter so that the rubber bell shaped end extends slightly beyond the end of the 3/4" PVC it will provide a cushion when the piston comes down. This piston will retract by gravity when in a vertical position but some other method of retraction (springs?) must be used in other positions. You could easily insert a spring inside to force retraction. Or mount one on the outside from the base of the cylinder to the top of the ram. On some applications the stress on the 3/4" PVC might be too much, just substitute 3/4" steel pipe instead. I found that using 3/4 steel pipe allowed me to attach something on the working end. Of course you must plug the bottom of the ram so air will be prevented from passing through. I just hand threaded a 3/4 PVC end cap onto the ram threads and it worked fine.

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Copyright 1996-2002 by Lawrence H. Lund Last Modified on: November 2004