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The Pocket Sluice

Author Topic: Built my own drop trap sluice  (Read 92044 times)

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Offline astrobouncer

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Re: Built my own drop trap sluice
« Reply #10 on: February 03, 2011, 11:50:47 AM »
Mines mostly done, just waiting for the waterproofing to dry so I can test it out.




Offline Vagadero

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Re: Built my own drop trap sluice
« Reply #11 on: February 03, 2011, 02:09:32 PM »
Can you post a front and a side view, if it's finished picture please?

Offline astrobouncer

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Re: Built my own drop trap sluice
« Reply #12 on: February 03, 2011, 03:51:51 PM »
Here's some improvements I made over the Bazooka.

My version has a pre-screen in the front to block leaves from clogging up both the pipes, and the grizzly which is super annoying every time you walk in front of the sluice you kick up leaves or other debris. And on the bazooka you have to bend down constantly and pull them out. No more for mine. This pre-screen is easily removable at the creek in case you need to clean it out. I used some 4 mesh. I could and might go smaller if needed. This is the front view.  



My version is also 8 inch's tall versus the bazookas 6 inch. Some of that is due to the larger wood base, but only 1/2 inch of that.

My version also has a 1 and 1/2 inch gap from the grizzly bottom to the top,  versus the bazookas 1 inch gap. This lets more water in the top to help push the gravel into the trap. And that extra water flow will help clean out the trap since the trap acts like the base of a waterfall.  

The grizzly on the bazooka is a mere 3 inches long, whereas the grizzly on mine, is 5 inches long. This extra length ensures the gravel is classified properly into the trap.



My version is also considerably narrower then the bazooka at the end, which should increase water velocity considerably to help push the oversize gravel out. The narrowest point on the bazooka is 9 and 1/4 inch, whereas mine tapers down to just 6 and 1/4 inches. Either will process a full shovel of bank run dirt, just mine will do it faster due to increased water velocity.

Mine cleans up into a 5 gallon bucket, same as the bazooka.

Either tomorrow, Saturday or Sunday I will try to get some testing in on this, depending on the weather.

Side view isn't much to look at, just looks like 2 4x4s stacked together. But if you want a pic I will try to get one up tomorrow.  

I tested a version of the screen already using both a 4 mesh classifier in front of my sluice and a screen on the bazooka and both worked great. Its a lot easier to reach down and move 20 leaves every couple minutes then constantly bending down to remove one or two every time you walk. And then when you come back with the shovelful of gravel more leaves are on the grizzly so you cant put that shovelful into the sluice because the leaves block the grizzly and let the material ride the current up and out. Remember I made these improvements into the sluice based on the testing I did with Indy's bazooka. Also the leaves on the screen actually helps the current build up around them since they form a restriction and a pool of water will form around the sluice. And around the bottom and top of the screen the current is increased. Then when you do remove the leaves all that extra water from the buildup surges into the sluice to help push the gravel out. Its a win win situation. And while the new leaves are building up, the water is building up too for the next time and the next big surge.  

The bazooka does not have this benefit as the buildup is inside and makes the traps not work. And the buildup of a couple leaves on the bazooka grizzly is not enough to increase the water buildup, thus there is no water surge when you free the couple leaves.

I am using both outdoor deck varnish, and thompson's water seal. I will also use some marine varnish when those dry. My standard water proofing way. My drop riffles still bead water using this method after a year of use.

I plan some other changes too, but I want to see how this prototype works before I go jumping into the next round of modifications. I forgot to add that mine should funnel water into the lower water pipes much better then the bazooka does as well. Let me explain why.

On the bazooka the forward motion of the lower incoming water into the tubes is mostly wasted because that water hits a wall and bounces back. Then it has to turn a steep corner to go into the Bazookas water tube. And all of the momentum it had coming forward is lost.

See this pic:



 On the bazooka for some awful reason they have the tubes out an inch or so from the back of the wall. That is wasting the majority of the kinetic energy of the incoming water. I have a hunch they did this to keep silt out of the pipes, but I still dont think thats a good design.  

Now look at mine. And imagine a great roaring jet of mountain river water coming down both these designs, which do you think it would rather go down?



Kinetic energy of the incoming water will hit that same wall but the capture area is not stuck out and redirecting the energy backwards.My tubes are flush with the wall, if a little recessed even. And also on mine the tubes are larger and will direct more water into the pipes with its kinetic energy intact.  I still want to put in some flow directors as well, to further help the water funnel into the tubes. Kind of like an intake manifold on a car. But that might not even be needed, we will see what testing shows.  
 
Now its true I might get some free floating silt debris in there, but I don't think its much to worry about. And the bazooka gets silt debris in there also.

I haven't weighed it yet, but it is definitely heavier then the plastic bazooka. Its comparable in weight to my 5 foot long wooden sluice with Hungarian riffles. I think it is about 12-20 pounds in weight but not sure. I will weigh it tomorrow to get the exact weight.  

As to how to carry it, I actually hadn't thought about that. So I guess I dont have all the angles covered. I have a spare adjustable military belt I can use as a strap. Or I might put a handle on it, I bought a couple of them for use with my drop riffle sluices. I have a hunch this thing is just a tad too heavy to rest comfortably on a strap, especially when wearing a backpack.

Offline muconium

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Re: Built my own drop trap sluice
« Reply #13 on: February 14, 2011, 06:43:36 PM »
Just a thought off the top of my head:

Is there, or should there be, an ideal balance between the water pressure of the intake pipes (located in the trap) and the water pressure of the trap-inlet under the grizzly? In other words, could running a drop trap with too little water running down the slick plate and into the grizzly/trap-inlet cause material to be flushed from beneath and out the trap outlet?

Please be patient with me: I'm trying to understand how these work so I can build one.

It seems to me that the trap-inlet should be gapped larger than the trap-outlet...........
Rusty dirt makes me drool.

Offline yicke

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Re: Built my own drop trap sluice
« Reply #14 on: February 15, 2011, 07:34:34 AM »
This is also a question I have thought of. If you look at the patent for the Schmidt Black Magic Sluice it is designed differently than the Bazooka. I think astrobouncer is the only one to answer that question as it will be a couple more months before I will be trying any of my designs.
free patent Schmidt sluice

Offline muconium

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Re: Built my own drop trap sluice
« Reply #15 on: February 15, 2011, 03:36:02 PM »
I didn't have to work today, so I've been mulling this over all day.

Of course you don't want two equal pressures coming together in the trap because they would cancel each other out.

BUT!

I wonder if it would be worth locating the trap outlet HIGHER than the trap inlet. Make them both the same size (1.5 inches, like Astrobouncer's), just make the material work a little harder and stay in the trap a little longer before exiting....

Hopefully, you guys are up to knocking ideas around on this thread.




Modifying my post:

I don't know if you guys saw the thread that Vagadero posted ( http://49ermike.com/dc/dcboard.php?az=show_topic&forum=181&topic_id=83765 ) but there is a lot of detail in it from another forum about the workings of fluid bed systems.

Some ideas I found interesting:

1. Situating the tubes at right angles to the material-flow.

2. Each tube having progressively smaller spray holes to ensure fine gold retention: widest holes are at the intake for added pressure to break up clay; finest holes located at the outlet so fine gold doesn't get blown out.

3. Putting compartments, or riffles, in the bottom of the trap to stop gold from migrating.

I'm not so sure about having a vast network of tubing in the trap to create the right angles. I think the extra plumbing would take up too much room in such a small trap............

Anyways, those are my thoughts for the day. I hope to begin soon on the general carcass of the box. I'm a substitute teacher, so I have the luxury of making my own schedule, so I want to start this project tomorrow...
Rusty dirt makes me drool.

Offline muconium

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Re: Built my own drop trap sluice
« Reply #16 on: February 20, 2011, 06:12:40 PM »
Okay. Been working on my box project.

I decided to build one that has dimensions exactly in between Bazooka's "Prospector" model and their "Miner" model. The Miner is 48 inches long and the Prospector is 30 inches. So mine is 39 inches. I also kept all the same proportions as a Bazooka product, since I don't have any experience with a box like this. If I want to fiddle with anything like water-pressure in the trap later on, I will just make a new one.

Here are the rest of my specs, in case anyone can use them:

39" long
Upstream flare width: 27"
Downstream width: 11.5"
3" high scoop

1/4" bar-grizzly just like Bazooka.

Top and bottom are 1/2" plywood, scoop walls are 3" x 3/4" red oak, as are the front and back wall of the trap.

I'm using 2" aluminum angle for the sides of the slick plate, to cut down on the weight of wood. I also want to use sheet metal for the slick plate. This will be epoxied down and screwed.

I want to leave the entry-gap width flexible. Astrobouncer changed his to 1.5" from Bazooka's 1", so it's a variable that I want to experiment with. I have a feeling that the flow of gravel and water into the trap from the top has to be in some kind of balance with the pressure coming from beneath from the tubes. So I want to leave the topflow gap adjustable.

I want to try out that spray-on truck-bed liner as a coating for the entire box, inside and out. Can anyone advise about this? It's supposed to stick to wood, but I have questions about its ability to stick to the epoxy I used on the seams.........

Ficke and Astro: what size did you guys drill for the spray-holes on your tubes? It looks like Ficke used a 1" tube and Astro used 1.5" PVC, but I'm in the dark about spray hole width.

Thanks in advance for any input you guys can give me! Photos are coming!
Rusty dirt makes me drool.

Offline astrobouncer

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Re: Built my own drop trap sluice
« Reply #17 on: February 20, 2011, 07:25:13 PM »
I used 1/8 inch holes on the bottom and sides. If I had it to do over again I would have done the front holes 1/8 and 1/16 on the backside where water exits the trap. I will probably change this anyway, as well as redoing it with the 3 smaller pipes instead of 2 medium sized ones, and turning the water pipes sideways to the water flow.  Also, I am putting a 'brush' on the inside of mine to help redirect the fines into the trap, and to try and settle out the fines which have a tendency to flow out of the trap with the slurry once you get some gravel in the trap, the large gravel (bigger then 1/4 of an inch) acts as a 'soft bedrock' through which the fines float over with too much flow. This problem can be cured by either slowing the flow of the water entering the top of the bazooka down, or classifying the gravel even smaller then the bazooka grizzly seems to help as well.

 

 

Offline muconium

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Re: Built my own drop trap sluice
« Reply #18 on: February 20, 2011, 09:54:17 PM »
Thanks, Astrobouncer!

I haven't spaced my grizzly bars yet, so maybe I'll go smaller than 1/4". Maybe to 3/16 or 1/8". I know for sure that I could classify right down to window screen size and still not exclude any Michigan gold, but I like to dream of bigger gold..... I also like to look through the bigger heavies at the end of the day and keep the bigger garnets.

Thanks for the tip on the "brush" idea. I wonder if you could retrofit your current box with a higher exit slot and get the same effect? I, so far, am keeping my entry and exit gaps level and the same size, since that looks like the standard on the Bazooka. I'm just using Bazooka as a standard that I can deviate from, once I get some experience with it, just like you have.

I've been wondering about facing my spray-holes upwards, like the fluid bed system discussed on Vagadero's thread. Specifically, does this create a more "quicksand" -type surface to the bed to encourage heavies to drop, or would it just push color up and out of the trap. Another question I've had is whether a fluid-bed of black sand would actually help gold to settle, just like the layer of ball-bearings in a jig. If so, there wouldn't be much demand to stop and clean out the box every half hour.

These are all questions that have been circling my brain as I try to think through the design....
Rusty dirt makes me drool.

Offline muconium

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Re: Built my own drop trap sluice
« Reply #19 on: February 21, 2011, 06:06:55 PM »
Guys, have you seen this?

http://49ermike.com/dc/dcboard.php?az=show_topic&forum=181&topic_id=83896&mesg_id=83896&listing_type=search

Lots more good fluid-bed stuff.

I just took the time to actually read the Schmidt patent. Not much new information, with the exception that he created a much more "closed" trap. in the sense that the entrance and exit for the trap located *over* the trap, rather than at the beginning and end of the trap. In other words, if the trap was a shoe box, the material enters through a slot toward the center of the lid and exits through a slot in the lid that is few inches back of the opposite wall. The Bazooka looks as if the shoebox has no lid. The patent says that these "overhangs" above the trap are "important to the operation of the device because when the fluid and material enter the first opening there is a tendency for the fluid and material to move directly to the second opening and immediately exit carrying some of the desirable material [gold] out of the container. The overhang causes the flow to strike the side and the overhang and curl back against the flange where it is directed downwardly toward the center of the container. This gives the heavier material a greater opportunity to fall to the bottom of the container."

Here is a pic:


 [ Invalid Attachment ]

Notice that there is also are "flaps to help deflect material in and out of the trap... I think I could probably add this stuff to my box, since I'm not actually to the stage of mounting the piece of wood over my trap that supports the grizzly.

I'm kinda curious as to why the Bazooka company left these details out of their design.............
Rusty dirt makes me drool.

 


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