Flared dredge sluice box?

[Vagadero]

What are the advantages and disadvantages of the falred sluice design?
How does the falred sluice compared to over/under ones?

 

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[63bkpkr]

The flare simply gathers in more water. If you have plenty or a great deal of water then the flare might make setting the sluice up more difficult, IMHO.
Hopefully others will respond to your questions......................63bkpkr

 

[Hoser John]

My ol'bud the late GREAT Karl Von Mueller introduced his flared dredge box design in the mid 70's as the Spartan Dredge,in his Examino Press publication. He was/and always will be the father of modern god minng/treasure hunting methodology. The flared design is still utilized by Dahlke drede company--or it was a few years back still anyhow. My bud Bob D still has his 70s 4" dredge made by KVM. On dredges with NO flair on the jet it's a good idea as it spreads out the flow,slows it down to give it enough time to deaireate a bit. On the Lindens 8" I built a over/under for the last 30"s and it also increased the take a flour gold X 10 fold. I personally much prefer the jet flared as then recovery starts much sooner in the recovery box as then the over/under takes over for fines recovery immediately. Nuttn' bad about'm except a bit wider but no big deal compared to a triple sluice(thank Robin Lee at TE n'the 70s). I have blueprints in my library somewhere I'm sure. lotza luck-John

 

[rodoconnor]

For that matter, the good old La trap sluice is flaired. Idaho dredge builders use flaired sluices as well. KVM was so far ahead of his times and was obviously generous to a fault as far as educating and informing.

 

[Real de Tayopa Tropical Tramp]

Caballero & miners: I have always assumed the max recovery of fines was to get them under the surface tension. So on tables, I simply floated a sheet of light plastic on the incoming flow surface with 'very' satisfactory results.

Soo gentlemen your opiniions or questions?

Don Jose de La Mancha

 

[omnicron]

Gold Dredge Builders Warehouse Alan Trees builds flared sluices on his dredges and from what I understand, work really well. I played around with a home brewed flared sluice last year and it worked really well.

 

[Timberdoodle]

A flared sluice used in a dredge configuration must still maintain a minimum water velocity and depth to clear large material. It's advantages will be that velocities are changing through the sluice allowing for different action of riffles etc..which will help capture different fractions of gold. If you deploy this methodology, take advantage of the different velocities by using appropriate riffles in the box ( high velocity-Clarkson, lower velocity expanded etc..) by running the expanded in the lower velocity end of the box you will also reduce the chance of hang-ups of larger rocks. Disadvantages- must still maintain overall higher velocity of water flow in areas designed for fine gold to clear larger material and scouring of the riffles will always present a problem.

Over-under Clearly has many advantages by running smaller material at slower velocities over appropriate riffles and keeps larger material from scouring the riffles. Disadvantages-complexity and getting it right. I am sure that anyone who has built and tested their own o/u designs has found that this is a different animal entirely. You are dealing with a sub-surface environment at this point and water flow rates in the under sections and to the under-sections(including material flow) are now a function of pressure differentials. Getting a box "tuned" to operate properly can take quite a bit of work but it is worth the effort.

A combination of the two designs would certainly be interesting (flare only the under-sluice) My 2 cents

 

[Hoser John]

Clarkson was a SLUICEBOX and not a dredgebox which maintains much higher velocities,gravel capacities and water capacities. KISS keep it simple and stupid. Over under as originally developed by PESCO,an industry standard ,does a fine job and a flared bottom would be a ungodly fab job,insane over complication and adding too much weight and width for nil advantages. That's why the simple o/u took over soooo fast. We refused to go through patent bs as what's good for the goose should be shared. I only fabed the last few feet of o/u on the 8" dahlke because that thang would absolutely NOT hold fine gold ,even with the box flared. It's Imperative to deaireate and drop that gold out of the flow asap and NOT when it's built velocity moving down a fast moving dredgebox and then inertia steps in and your specific gravity advantage is greatly reduced-John

 

[Timberdoodle]

Good points as usual John. I fully agree that deaireation and getting the gold removed from the high velocity flow asap is one of the key functions of a well designed o/u box. I do not dismiss the use of Clarkson riffles in a dredge though. They work best with fast flows and generate the needed vortex energy to draw the gold out of it's desired path in fast moving water. To clarify this further, the specific gravity of gold helps in it's collection if we want it to "drop out" in slow to medium flows. The specific gravity also works against us in high velocity water because of it's mass and it doesn't want to change it's direction of movement without strong forces being applied to change it's direction. That is why I feel that Clarkson style riffles can benefit a dredge when installed correctly and at the right locations - just my opinion.

To keep it simple on the flare/o/u design one possible way that would not require extensive fabrication might be to fabricate a flared box as desired and install the punchplate as a 3 sided box maintaining the same width of the punchplate from the entry all the way down the box. As the flare requires greater water flow more water/material will be drawn through the punchplate while keeping the larger material inside it's own sluicebox area. I have not tested this, just a thought that I figured might be worth testing if anyone is interested. Being that said, the challenges of building a good working o/u box are many and this idea may not hold any merit. I personally do not lean to using punchplate due to it's low area ratio of openings and find that a considerable amount of material will simply flow over the openings in fast moving water flows and it also makes it difficult to get enough flow to the under sluice for proper operation, but again that's just my opinion and food for thought.

 

[russau]

ive been useing a 4 inch over/under dredge for 8 years now and it works for me! a couple of years back Hoser gave me some Veranda carpet to replace my miners moss. i wont go back to miners moss! EVER!