A hand dredge, also called a gold sucker, is basically a pump that will allow you to suck up material. They allow you to suck up material in hard to reach places, such as under rocks, and in crevices. Hand dredges work extremely well if you are prospecting for gold as they allow you to quickly move lots of material.
30" 1-1/4" PVC
36" 1/2" PVC
1x 1-1/2" ABS Wye Fitting
1x 1/2" PVC Slip Cap
1x 1/2" PVC Threaded Cap
2x 2 1/4" PVC Slip Cap
3x 1-1/2" x 1-1/4" PVC Bushing
1x 1/2" Slip to Threaded Adapter
1x 1/2" Foam Pipe Insulation
1x 1/2" Elbow
1x 1-1/4" x 1/2" Reducer Coupling
I purchased all of the parts new for just under $23. I did not have to buy any of the tools.
Dremel or Sand Paper
Pipe Cutter or Hack Saw
This dredge is not my original design, it's based on this: http://www.youtube.com/watch?v=YCozzarSk5A
Please note I am not responsible for anything you do, so please only use my instructions as guidelines. Use proper safety equipment and common sense. Also check with local laws to make sure you're allowed to use a dredge in your local area.
Step 1: Step 1 - Drill Cap, Sand 1/2" Adapter
Find center of 1-1/4 PVC Cap and drill a hole that is 5/8" in size. Slightly larger than the 1/2" PVC pipe. It doesn't have to fit tightly, it's really just for aesthetics, and to keep the handle from pulling all the way out.
The easiest way to find the center of the circle is to place a square over the circle, lining up the the point on the edge of the circle. Then mark the spot where the square goes outside of the circle. Draw a line between two marks. Repeat this again by moving the square part way around the circle and drawing another line. Where the two lines intersect is the center of the circle.
For more in-depth instructions:
Next you'll want to use a dremel or sand paper to sand the PVC Bushing (1/2" slip to 1/2" threaded) so it can fit inside the 1-1/4" pipe.
Step 2: Step 2 - Cut PVC to Length, Create Seal
You'll need to cut the PVC accordingly:
Once done, cut about 1/2" of the pipe insulation to create the seal. Remove the plastic from the insulation and glue the two pieces together.
Step 3: Step 3 - Dry Fit
Dry fit the pieces accordingly to make sure everything is the size you want and that you have all the parts needed. Make sure the ABS Wye connector has both ends facing down with the other end connecting to the pump section. That way as material falls down, it can collect inside the part with the cap.
To create the pump section, take the 24" long 1/2" pipe and pit the 1/2" elbow on one end. Then put the 1-1/4" cap with the hole drilled in it over the pipe. Then, place the 1/2" slip to 1/2" thread bushing onto the end. Take the pipe insulation and place it over the threads, then screw on the 1/2" cap. This creates the seal needed for the pump. On the other end, take the 6" long 1/2" pipe and connect it inside the elbow. Then place the 1/2" cap over the pipe. This is the handle.
To create the collection piece, take the 6" long 1-1/4" pvc and place the undrilled 1-1/4" cap over on end. The other end is then connected to the 1-1/4" to 1-1/2 bushing. This is then inserted into the 45 degree part of the ABS Wye connector.
To setup the sucking piece, take the 6" long 1/2" pvc and insert it into the 1/2" x 1-1/4" bushing. Then insert that into the 1-1/4" x 1-1/2" bushing. Then, insert that into the bottom of the ABS Wye connector.
If you can find a 1-1/4" wye connector, then you could leave out the 1-1/4" x 1-1/2" bushings, but I wasn't able to find one. hence why I used so many bushings.
Finally, insert the 24" long 1-1/4" pipe into the top of the ABS Wye connector. Then insert the handle assembly into it. There should be a tight fit. Connect the top cap where the handle bit is. That's basically it for the dredge. Now you'll just need to glue it together.
If you pull the handle up, you should be able to suck up water from the sucking end. If you hold your hand over it, it should feel some force when you pull the handle out. Or if you push the handle, you should feel air on your hand. This means the pump assembly has a good seal and is working correctly.
Step 4: Step 4 - Glue Pieces
This step is pretty self explanatory though you won't want to glue everything together, just key parts.
Start by gluing the handle assembly together, the end cap, elbow, and 1/2 slip to 1/2 thread connector. Don't glue the cap on the handle assembly to the 1-1/4" pvc as you'll want to be able to take it apart to clean it out or replace the seal.
Once done, insert the handle assembly where the seal is at into the 1-1/4" pvc like you did in the dry fitting.
Next, glue the cap onto the 6" 1-1/4, then glue the pvc into the bushing. Do not glue the bushing into the ABS Wye connector. This is where material will collect and you'll need to be able to take it out to pan through your material.
After that, to create the part that sucks up material, glue the 6" long 1/2" pvc into the 1-1/4" to 1/2" bushing, then glue that into the 1-1/2" to 1-1/4" bushing. Do not glue this to the ABS Wye - you'll need to clean this out occasionally.
Then, take the 1-1/2 to 1-1/4 bushing and glue it into the top of the ABS Wye connector. Do not glue the handle/pump assembly into this bushing. Dry fit the handle/pump assembly, collection piece, and sucking end together and then it's complete!
Step 5: Complete!
Your dredge is now complete. To suck up material, just keep the collection piece faced down and pull the handle to suck up water and material. As material falls back down, it will get stuck in the collection piece. Water will then drain out the end of the pipe. Keep doing this until you think the collection piece is full.
Then loosen the collection piece and pour it into your gold pan. Rinse then connect it back together and repeat!
Good luck with finding gold! If you have any better ideas, please feel free to share them.