8 inch gravity sluicing

[spaghettigold]

Hi,everybody ,in my earlyer beginner times(i,m still one) i gathered some infos from this forum,maybe i can inspire others too.
Thanks,saluti from europe ;emilio

 

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[GrizzlyGremlin]

Hey spaghetti nice builds, prob covered but how much head do you need for proper sluicing on that 4".
Will it be less head required with the 8?
Nice thread btw!

 

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[spaghettigold]

should,nt gremlins stay away from the water?

Here on the goldfever site A Gold Fever Experience - Gravity Dredge Plans - Olympic National Park go to;graph for determin the waterflow.

However,i,m no good mathematician,do things more by instinct.
From what i understood so far it depends on your hoselenght and the bends or dips on the way to the sluice.The longer the hose the more friction,the more head you need.But not in a linear proportion.
Also it seems that a bigger diameter needs a little less head because there,s a bigger watermass in the middle of the hose that is not exposed to the hosesidewallfriction.Somebody may correct me if i,m wrong.
In the hoselenght range i used so far ,between 16 and 52 feet.as a rule of thumb it worked with around 10 percent head in relation to the hoselenght(30 feet of hose with 3 feet of head ) .If the material you want to suck up is much deeper then watersurface level of your upper pool(where you dredge) you loose force too when rockweight comes in to play.Daming up will increase the power in that case,but as most gravitydredgers have no oxygen for diving that may lead to longarming or prevent you totally from dredging.If working in watersheds with poor drop available,its often the geology of the river that predicates where you dredge and that unfortunately is not always the place with the best gold.- Emilio

 

[GrizzlyGremlin]

Totally, i always thought a gdredge could run with less than the 10' of drop some people say is necessary. In the right spot i bet its deadly, and silent!!!
I used to use a 1" 10' piece of tubing to siphon cracks into a bucket not a sluice, with just 1' of drop.
Im following your 8" adventure. Very interested. Ive got spot begging for a gdredge!!

 

[Bonaro]

Just go to the sewer pipe department at Lowes/Home depot and life gets easier...and much cheaper. Sucking ANY air is the killer as much prefer a solid piece of hose or junctions should be fabbed to remain underwater so any suction leaks suck water and NOT air as then slowly but surely your prime goes unprime and your left standing there holding your hose John

Hojo - try shaking your hose, that may prime it again

 

[spaghettigold]

Totally, i always thought a gdredge could run with less than the 10' of drop some people say is necessary. In the right spot i bet its deadly, and silent!!!
I used to use a 1" 10' piece of tubing to siphon cracks into a bucket not a sluice, with just 1' of drop.
Im following your 8" adventure. Very interested. Ive got spot begging for a gdredge!!

Hi gryzzly.It,s absolutely doable.But thinking about it..Maybe those people that claim that 10 feet are required, had to dredge thru 6or 7 feet overburden to get theire gold,loosing force on the way down,thats maybe a explanation. In my flypoop creek i just have to suck up the first 2 feet or so,and in my big flake river i had average of 2 feet to the claylayer bedrock,with still paying overburden,could be its because of that.
Like you say in the right spot its really effective.If for instance i was a claimowner in a steep creek with constant drop available,dredging for a living,i would give it a try even when i was allowed to use motors.Saving gasoline coasts,motor maintenance coasts etc.
Glad you like the thread.Don,t take for science what i,m telling i,m still a amateur,it would be nice if there,s some hidden gravity dredge -crack lurking around here to chime in if i,m telling crap,aswell because in the future i may have some questions too. I,d like to see threads from other gravity dredgers and theire experiences.

 

[spaghettigold]

Hojo - try shaking your hose, that may prime it again

Please stop scare me of the days to come

 

[spaghettigold]

Hi all

Went to metalman today and fetched my dredgeframe.
It is at minimum specs right now and i,m looking forward for a testing opportunity.
Weather forecast predicts heavy thunderstorms followed by wintercomeback this weekend.
Also have to find a suitable creek with drop cause my standard creek is to narrow /shallow for the 8 inch.



cheers;emilio

 

[BurntBear]

Nice!

 

[spaghettigold]

Thanks luke
Hope it will not be a submarine..

 

[spaghettigold]

went for a location prospecting trip to my homecountry lately,met my minerbuddy..
some impressions:

we were looking for some spots with available drop and came across this natural riffle
Unfortunately no drop there and time was short,we had to move on as i had only two days for location seeking for my set up and discuss the modifications that we have to built on the sluice and frame.

 

[spaghettigold]

for some cultural enrichment,we also came across a not so recent recovery system,a 30 feet sluice box built by the old romans.
They had some wood bars across the sluice as riffles.

 

[spaghettigold]

150 feet away, a "quarry"..(cough,cough)

who,s hiding there?

 

[spaghettigold]

View attachment 1168243 good old trommel

cheers,emilio

 

[spaghettigold]

inserted the barrels for the first time and drilled some holes for adjustments yesterday

today i built a frame for a winch from scrap-parts from a construction lot. Winch is for sluice adjustment help.

Cheers; emilio

 

[spaghettigold]

Hi all. Back from a trip.

MercifullyIt floated good

 

[bill-costa rica]

looks good, you might be able to remove 1 barrel on each side. give you a little more slope to the back. or just leave it like it is if it works >)

bill/cr

 

[fowledup]

*****in! Looks awesome! How'd the monstor do?

 

[djpitr]

Great build where is your motor ?
I started on mine 4" with same drums

 

[spaghettigold]

looks good, you might be able to remove 1 barrel on each side. give you a little more slope to the back. or just leave it like it is if it works >)

Experienced eye bill

the slope was indeed too steep ,especially with the c.a 6.5 feet of drop that we had in this spot that transformed the dredge in a mini excavator.
But this was the first real world floatation test ,later we took adjustments.
The sluice can be slided forward/backwards and can be adjusted also up and downwards.The range of adjustments has to be much bigger in a gravity dredge because theres no throttle to regulate the waterflow .
I wanted 8 barrels because of my flash flood experience last year .I want the dredge barrels to stay above water as much as possible.Fortunately this time no floods,it was bone dry ,only 1 half our rain this time.
Here a vid from the test.

After adjustments we dug our first testhole in that spot
It was the first test hole of many with almost nothing worth working in it.

 

[spaghettigold]

*****in! Looks awesome! How'd the monstor do?

Hi fowled.
Technically it worked good,i got to know my dredge better,also some week points .
Its a long term project and i will try to improve the dredge over the years and paychecks.
For example i have to built a clean up sluice with separate 2inch hose or so that i can mount on the pontoonframe ,because cleanups and then setting of clean up sluice in the river was always time and energy consuming,especially if the ideal setup spot for the clean up sluice is distant from the mothership and you carry the concentrates in the river.
Also some other issues to work on.

The main problem this time was that my mining buddy,because of serious family issues, had no time to prospect a spot with both drop for the hose and gold in the ground,previous to our trip .Our deposit from last year was devastated from a flood last year and does not exist enymoore.
And so we spent almost one and a half weeks setting up everything,dredging a testhole-little gold,dismantle everything moving to another spot and the whole story again and again.
A few days before the end of our trip we got to a place that gave us a bit more gold and we decided to stick to the spot.
We dug deeper and a big boulder appeared. And so we tried to clean around him but unfortunately the trip ended before i could clean up what was under the boulder.The goodies,if there are any,are still there.