This Instructable will show you how to build a cheap air ram for holiday props, robotics or whatever else you want to do with em! You could just go out and get a screen door closer, but for the price of two and a few extra steps, you can make around 10 of them a foot long ! If needed, you can change the length of the cylinder as well as the diameter of the pipe used. Here I am using 1/2“ pvc. If you want to use larger pipe, you will have to do some trial fitting at the hardware store for a piston and seal. Let’s get to it!
Step 1: Materials and Tools
1/2“ sch 40 pvc pipe
1/2“ end caps (2)
1/4“ steel/aluminum round rod
1/4“ 20 nuts (2)
Plastic bottle cap
5/8 o.d. 5/16 i.d. rubber grommet
5/8x1/4x3/8 nylon spacer
1/4 20 die
Sand paper or belt sander
Step 2: End caps
Drill a 3/8 hole in the center of one 1/2 end cap and a 17/64 hole in the other.
Thread in the air fitting into the cap with the lager hole and put this one on the 1/2 pipe.
On the pipe, you may need to bevel the inside edge of the opening to make inserting the piston easier.
Step 3: Piston
Take the nylon spacer and see if it fits easily into the 1/2 pipe. If not, lightly sand it down so it slides very easy in the pipe. A belt sander is handy for this!
Take the bottle cap and cut a washer the same size as the nylon spacer with a 17/64 hole in the center.