The hand dredge has many nicknames, including gold sucker, crevice sucker and picker stick. During the California Gold Rush, hand dredges were used to extract gold-rich earth from streams and other small bodies of water. They are used for the same purpose all over the world today. You can build your own hand dredge by simply gluing together together a body and plunger from pieces of PVC piping. The plunger absorbs soil, earth, and hopefully valuable materials into the body. You can then dump the contents of the body into a sifter to complete your prospecting.
Assembling the Body
Apply a thin layer of PVC cement to either tip of the 6-inch length of 1/2-inch PVC pipe and glue it to the 1 1/4-inch-by-1/2-inch reducer bushing. The tapering of the reducer bushing will prevent blockage when you start to dredge.
Complete the nozzle by gluing the outside edge of the reducer bushing to either end of the 1 1/4-inch-by-1 1/4-inch bushing. The nozzle is made up of the 1 1/4-inch-by-1/2-inch reducer bushing glued to the 6-inch length of 1/2-inch PVC pipe on one end and the 1 1/4-inch-by-1 1/4-inch bushing on the other.
Glue to nozzle to the 24-inch length of 1 1/4-inch PVC pipe. The nozzle and the 24-inch length of 1 1/4-inch PVC pipe make up the body. The plunger will be inserted into the body to create suction when the dredge is complete.
Assembling the Plunger
Cap off either end of the 4-inch length of 1/2-inch PVC pipe by gluing it to the 1/2-inch unthreaded end cap.
Glue the opposite end of the 4-inch length 1/2-inch PVC pipe to the 1/2-inch-by-1/2-inch slip elbow.
Glue the opposite end of the 1/2-inch slip elbow to the 22-inch length of 1/2-inch PVC pipe.
Glue the other end of the 22-inch length of 1/2-inch PVC pipe to the 1/2-inch slip to 1/2-inch threaded bushing.
Fit the 3/8-inch length of pipe insulation onto the other end of the 1/2-inch slip to 1/2-inch threaded bushing.
Complete the plunger by gluing the threaded 1/2-inch pipe cap to the 1/2-inch slip to 1/2-inch threaded bushing.
Insert the plunger into the body. When you draw on it you should get a suction effect forceful enough to draw rocks and soil into the body for prospecting.
If you would like to use different nozzles with the same hand dredge, do not glue the nozzle to the 24-inch length of 1/2-inch PVC pipe in step 2 of building the body. Instead, simply squeeze the nozzle onto the 24-inch length of 1 1/4-inch PVC pipe.
Your hand dredge will not hold its suction for long, so you have to transfer the materials to your sifting machines quickly.