100 Pound propane tank (second tank optional)
120/220 volt electric motor
Flat Iron 3"
10 " steel U-channel 32" long
one way air valve
Tank water drain valve
Variety of brass and gas pipe fittings.
Pipe joint compound
To start with and this is very important, a 100 pound propane tank that is completely drained of propane and should be aired out for at least several months as you will be welding to this tank. I sure don't want anyone blowed up.
Take your 3" flat iron, should be 1/4" thick and bend it at both ends at 90 degrees. You will need two of these. The length of the flat iron is up to you depending on the height you want your compressor. My pieces were 26" long and the middle piece is 12" with the 90 degree bends being 7" on each side. These are the legs. Weld these legs to the propane tank at the front and back making sure they are level with each other. With this done you can now place the tank on the floor and it should be solid.
Next take your piece of 10" steel U-channel and put the air compressor motor at the back of the tank and electric motor the front on this U-channel making sure that there will be enough tension on the drive belt. Mark the position of the mounting hole on both. Drill out these holes. Now put in the nuts and bolts you will be using to mount these two motors. Turn the U-channel upside down and weld the nuts to the under side. Once these are welded, remove the bolts. Place the U-channel on the top of the tank, opposite the legs. Make sure this is level and weld the U-channel to the tank. At the back of the tank you will have to drill out a hole big enough to fit the seat of the one way air valve. You know have to weld the valve seat to the tank making sure you have a complete seal on the weld.
Turn the tank upside down so the legs are up in the air. At the front of the tank on the bottom (where the legs are) drill and tap a hole that will fit the brass fitting you will use as a water drain. Once this is done and the fitting is installed with a on/off valve, turn the tank back over and mount your air compressor motor and electric motor. You need to run an air line from the air compressor motor to the one way air valve at the back of the tank. I re-wired my electric motor from 120 volt to 220 volt and put a 220 volt plug on it. There was too much initial electrical drain when the motor started up on 120 volts and would blow breakers.
You know have the basic compressor done. You know have to decide on the configuration you would like for your air outlet. You will need a reduction fitting to fit into the threaded hole where the original propane valve was. From there install the fittings you want . You will have to incorporate the air switch in your configuration. I used a Penn switch that is wired from the electric motor then out to the plug in. I adjusted the air switch to shut off at 110 pounds of pressure. Prior to the air switch you will also need a air pressure relief valve. For my compressor I also put in a T-fitting to run a line to a second 100 pound propane tank for extra air storage. I also put in an air regulator on mine. Be sure to use pipe joint compound on all the fittings to seal them. You should now be able to plug in the motor and fill the tank with air.
This is fairly complicated project and requires careful planning. These are fairly basic instructions, but should be good enough to get you started. The biggest concern is to not weld through the tank. Dry fit all of your fittings to make sure you have the configuration the way you want. Good luck and if you have any questions please email. Looking at the photos will give you a good reference. I know there is a lot of smarter guys out there and if you have any suggestions on how to improve or simplify this project, your comments are most welcome and will those of you who decide to take on this project.