Pump Construction
Written by Drenchenator
Last updated on 2007-12-20
Theory
Pumps in separate chamber water guns do one thing: move water from a reservoir to the pressure chambers. This action powers the gun. The quality of the pump determines the success of a homemade water gun. I tend to choose quality, which is why I designed this style of pump.
This guide does not show or tell a builder where or how to attach the check valves. These are vital to build pressure and are discussed in the article Separate Chamber Design. This design creates a pump with about a 12 inch stroke. The stroke can vary though based on the needs of the new design though.
Materials
- 1" schedule 40 PVC
- 1/2" schedule 40 PVC
- 1/2" CPVC
- 1/2" schedule 40 PVC endcap
- 1/2" ID 5/8" OD O-rings (3)
- 1/2" wooden or aluminum dowel
- Epoxy
- Bolts and Nuts
Construction
- Cut two pieces of 1/4" lengths of 1/2" CPVC pipe, and cut 15.5" of 1/2" wooden dowel. Cut 4.5" of 1" Schedule 40 PVC pipe. Gather 3 1/2" ID 5/8" OD O-rings.
- With a pair of scissors, cut both of the CPVC pieces on one side to allow them to be slid over the dowel.
- Arrange the CPVC pieces on one end of the dowel, allowing 1/4" between them for the O-rings.
- Glue the pieces down to the end of the dowel. Let sit for the time recommended by the gun.
- Drill a 1/2" hole in an unthreaded 1/2" Schedule 40 PVC end cap.
- After the glue has set and the O-ring mounts are secure, sand them until they are about 1/16 of an inch thick (or until them can easily fit inside of 1/2" PVC). Sand the middle area where the O-rings will go as well, because this will give the O-rings more room.
- Place the O-rings in the mount, and put the end cap over the dowel.
- Drill two holes on the end of the dowel opposite to the O-ring mounts. Drill one 1" from the end and another 1.5" from that one.
- Drill two holes in the 1" PVC section, one one in from one end and another 1.5" from the other.
- Using spacers or washers (as well as nuts and bolts), make a handle from the 1" PVC and attach it firmly to the dowel. Cut off extra lengths of the bolts as needed. File the ends smooth.
- Insert pump rod into the pump shaft of the gun.
