My First Dredge Build/Lend Your Advice

[afreakofnature]

Well 2 years ago I embarked on building my own dredge, just because I needed a winter project. I acquired parts and pieces mainly for free or cheap, spending a few bucks here and there. The sluice, hoses, frame and nozzle came an old inner-tube Keene dredge. The sluice mats are Goldhog River hog. The 1/4 classifier tray is from grill cookware. The Aluminum bars and pump stand (frame) were from scrap at the welder's shop. The floats I got off craiglist. The pump was from my highbanker.
I made it so the old frame could adjust aft and bow so that it could hang of the aft more if needed. I also added the 2" exhaust tube to the crashbox so that a 2" hose would fit. My last steps are to 1.) See if it floats 2.) Adjust the balance from starboard to port. I think I am going to do this with a scuba belt and lead weights attached to the frame or floats. Being that the frame was the old kind where the pump was next to the sluice, I am going to have to do this. I looked at trying to make it so the pump was at the bow and the sluice at the aft, centered, but then I would have to make more of a frame and the sluice would sit at least half off the aft of the dredge. So I decided to stick with the original design and try to balance. I am going to get to do this in one of those Wal-mart inflatable pools this weekend.
I am not sure if the sluice magnet is really needed, I have had this thing laying around for years now and never use it. Trying to find some use for it somewhere and will probably attach it again to my highbanker.
The crossbars on the sluice are how I hold my Goldhog mats in place. They "squeeze" the sluice together which did a very good job for me in my highbanker. Just don't squeeze them too much or you will have a trough going down the middle instead. Just a little squeeze.

Let me know what you guys think or lend some advice. Unfortunately I do not have areas readily available to test this. I am going to take it on the road when I visit friends and relatives, like in Oregon, Wyoming and Georgia (on my way to FL).

 

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[omnicron]

Suggestion, turn your pump around as that will make your hose shorter and you have more flow.
Your sluice is to far from the water. Your going to lose lots of suction, especially with GH mat were you need lots of pitch. You want the front of your sluice to either just touch the water or a tad above.
As with Hoser mentioned with the single inner tube type of dredge, this one might also be unstable and prone to flipping. Watch out in faster water.

 

[afreakofnature]

Thank you for the suggestions. I can not turn the pump around or the intake will be facing the sluice. However I never gave thought to adjusting the frame and switch the sluice with the pump. The frame came already bolted together but I should check to see if it can be done. I am hoping that after I see it float that is will sink some to allow the sluice to be closer to the water, but if that does not work, I might have to come up with a new frame design. I was trying to keep it simple.

Since i have never dredged before I just assumed that if it was higher out of the water, that you would just get less depth in the water. Closer to water, more depth in water. Strictly based on "pump strength" thought only.

 

[omnicron]

You need to run water through it to get the true balance. Water is what 8 pounds per gallon so when you have water in your sluice it's going to change lots of things. If the intake is pointed to the sluice, that's ok as long as your intake is not hidden. You can route your hose around/over to the water or just move the engine to other side.
Another thing you could do is mount your sluice under your frame. Once you get it running in the water you'll have a better idea were you need to mount the sluice. Closer to the water, the better. You can still keep things simple but you also want things to work, right?
Look at dredge videos, you will see that the discharge end of the sluice is always at water level...some may be a little under but always close. The exception is the older triple sluice dredges, those sluice sat on top of the pontoons.

Here is a good resource:
Shacks Gold-Dredging

 

[afreakofnature]

I got thinking about lowering the sluice but I have to ask, would I really lose that much suction power? Highbanker dredges sit off the ground higher than this. I should be able to adjust my pictch more by moving the sluice/engine frame toward the aft of the dredge (I made 6 adjustments for this). That would give it more pitch I could also hang some weights off the aft too. Thank you for the advice of running water through it for balancing, I was planning on doing that as well too.

 

[omnicron]

I don't know the exact math but it's your choice, less suction = more plug-ups. Every time you stop to clear a plug up you lose production. Time is gold! My first dredge was a cluster #$%^, It was a high banker dredge and once I converted to just a dredge ie: lost the hopper, went to a flare, lowered the sluice down my production increased 2 fold. I had more suction and less plug ups.

 

[afreakofnature]

Gotcha, damn I would hate to start over with out giving it a test run. I would have to redo the whole frame, what to do? Hmmmmm.

 

[afreakofnature]

I could try to hang the sluice with chains. What do you think of that? More pitch adjustment then too and I could put the pump in the center for better balance.

 

[aarthrj3811]

I like the old header box design...Learn how to work the nozzle to prevent plug ups..Art

 

[omnicron]

Are those 2 pontoons on each side? If so, you could consider spreading them out, that would give you more stability. It would also allow you to mount the engine on the center line in the rear. Don't mount above your sluice. Leak some oil or gas and watch your gold float away.
It would also allow you more mounting options for your box. You could use chains on the rear of your box but on the discharge end, a solid mount would prolly be better but you could use chains.

 

[russau]

Omni gave some good points! i also just built another dredge (2inch)for testing my Gold Hog matting.i made it as a low profile dredge.the closer that eng/pump is to the water,the better your suction will be and less plugups like Omni mentioned. BUT in the same breath, a 2 inch dredge will only go so deep. try what you have and see how it works, but remeber Omnis words.

 

[afreakofnature]

Well I had to take the top frame apart anyways to switch the pump around. All with good success. In the process of doing that I went to see if the sluice would fit in between the pontoons and it does. With out a millimeter to spare. However what i noticed is this, for the sluice to have any support it would have to sit in the middle to middle aft. The pump would have to sit above the crashbox or slightly back. I noticed that it was going to be a lot of weight on the bow. I would have to offset that with some weight in the aft. Not only that I have no clue how low to make the sluice without knowing how much water the dredge is going to displace. I might make my sluice too low and the first test will put it to far in the water. Oh the trials and tribulations.
Anyways I am going to try out my design first tonight in the kiddie pool. I did noticed that the bow to aft balance (over a pipe) is about perfect, now I need to see about the starboard to port balance. and all with water flowing through it. Will update soon.

 

[omnicron]

It's hard to set the final sluice position without running water through it. If you seen my 6" build thread, I made my sluice 100% adjustable but never set the front 'till I ran it. I had it in where I guessed it would be but it ended up about 6" high lol.

 

[afreakofnature]

Its alive!! I got to test my dredge in a back yard kiddie pool. I am impressed. It seems to work. I just had to balance it from starboard to port. I am at the max in bringing the sluice/motor frame towards the aft with out the poontoons really coming out of the water on the bow. But I think I have enough flow for the goldhog mats. I need Doc to let me know if my last Riverhog should be trimmed more, there is a huge rooster tail in my opinion, however, it did hold up larger rocks, maybe more like a nugget trap?

 

[omnicron]

You need to look at the exchange happening in the mat ie: dancing particles to know for sure. Those larger stones should of cleared imo. Hopefully Doc will chime in as he knows.
Seemed like you have lots of bubbles on your water. It was better with your Alaskan damper down. Air leak? Did you see bubbles in your pump intake? Right at the pump is best place to look.
If you was to move your sluice down between the 'toons and motor back on the center line it would increase your stability. I understand you have the frame already but all it will take in one
tip over and your engine will be toast. That's my 2 cents. Not bad for your first build.

 

[afreakofnature]

I PM'ed Doc and here was his response;
"Looks good as far as I can see.
I would probably trim that last one a little bit.
When you get into the field you might have issues with rocks jamming there as they lose their energy towards the end as well.
Big gold is really never an issue for the river hog mat. Most of the time people just run it too slow and with too little pitch."

So one mod on the mats and I am good to go

I thought I had too many bubbles too, there was a small leak at the intake, and my buddy noticed it too and that the air might be a problem. I will have to remedy that. I thought the flow looked better with the damper up, but most of the water was going through the classifier and over the UR underneath so I will have to play with that in the field.

I thought about putting the sluice in between the pontoons but after seeing how much pitch I would need this would not be feasible with my set up. the sluice would have to come more up toward the bow so the box would not be in the water. I would have to to put the pump over the back end of the sluice to get the pitch and keep the bow/aft balance. I basically would have to make a new frame and get another set of pontoons if I wanted to keep the pump from above the sluice. All in all I think I would just buy a new one if I have to do that and scrap all the tinkering. Believe it or not, this thing is not so tippy. We really wanted to see what it could handle, you really have to put a lot of weight on the starboard or port side to try to get it to flip. I would not want to hang on this thing in the water though, that would be a problem. The only way that I could see it tipping is if a lot of weight was applied to the aft since the pitch is already in that direction. All in all, I am pretty happy with my first time putting something like this together, and to dredge my first material, granted it was from a 5 gallon bucket in a kiddie pool, the thrill was exciting. It was cool as hell to suck up gravel and watch it come down the sluice, boy it sure does beat digging.

 

[afreakofnature]

I added the aft outrigger last night to help prevent tipping. It can be adjusted up and down and back and forth over the frame bar. Pretty cheap add on and should help some.