rethinking parts of my 3" dredge build

[Jason in Enid]

I was able to get my homebuilt 3" to the river for it's first test run. Overall I have to say it was positive since there was gold in the test pan when I was through. Floats (15 gal barrels) worked great. Frame (1" alum square tube) worked great. Engine mount, motor and pump worked TOO good. Under-flow section of sluice with expanded over deep-V worked as hoped for.

The parts I'm not happy with... end of the box was in the water which is something I was hoping to avoid. Dredge hose sucked (in a bad way). WAY too thick and it has a permanent desire to be curled which made it's use difficult at best. swivel nozzle.... ... it seemed to bind up with sand every 2 seconds that I wasn't rotating it. Time to dump it and put the straight nozzle back on. Top riffles were a dissapointment. I used 4# expanded at the end of the box as a nugget trap/last chance fines catch. I couldn't keep it from packing with small gravel. it filled it up to the top and never wanted to clear no matter how long it ran with clear water or how much water I pushed through. That means anything greater than 1/8" would just keep moving over to the top and out of the box. I'm torn whether to replace it with a smaller expanded or to go with traditional riffles. Both have pros and cons, so I'm going to have to put some brain time to it.

As for the pump working too good... It's a Honda 6.5 motor turning a Keene P180 pump going to a 3" jetlog. The suction on the nozzle is strong enough to try and rip your hand off! It's also pushing so much water through the box that it was almost spilling over the top and I couldn't kept the turbulence under control. Running the throttle at about 1/2 speed helped but I need a heavier damping mat to try to control the flow too. I may need to use even less throttle. I need to get a tiny-tac so I can put some rpms to nozzle suction and box actions.

Those are my thoughts so far, there was gold in the test pan of the v-mat so I know at least that part is working. I think I need to slow the water down to give the fines more time to drop through, and maybe increase the pitch a little more than 1-in-12. Oh well, more to tinker with and play.

 

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[okbasspro]

Jason on my proline I got stock riffles up top run great. 3/4 expanded on bottom. I went to atwoods and got horse stall mat for my damper nice and heavy. Were you at K River?

 

[Jason in Enid]

Jason on my proline I got stock riffles up top run great. 3/4 expanded on bottom. I went to atwoods and got horse stall mat for my damper nice and heavy. Were you at K River?

Yep, the river level is finally low enough! It was a busy place too. A GPAA group from TX was there and there were probably a dozen other people down prospecting at the same time. The spring floods changed the river! The deep channel on the outside is filled in with gravel. The north gravel bar is about 1/2 gone. Just more flood material to go through! I saw Mike down there too. We got to spend some time catching up, so it was a great time all around.

I'm debating as to whether I want another small-expanded up top, basically mimicking the fine gold catchment of the bottom (since that is 99.9% of everything in the places I dredge), or riffles to hold the lead shot and any rare pickers I happen to suck up.

Are you using the 1/4" mat? Its not too stiff?

 

[Al(GA)]

Hi Jason --- I also use a 6.5hp (Honda clone) and Keene's P180 pump for my dredge/highbanker set up but more about my problem later.
As for suction hose, I use two types (1) a heavy duty type, I buy from Industrial Supply Inc. in Bellingham Washington (they sell on e-bay). (2) Keene's suction hose is lighter weight and more maneuverable. Both have smooth insides and would prefer Keene's when working in streams. I do mostly benches and old tailing piles (out of water) and prefer the heavier one for dragging over rocks, vegetation etc.

As for a dampener --- Dollar General sells heavy duty door mats for around $4 which you can cut to fit, They work great for me.

My problem is not enough suction --- I run my dredge (2.5") with a suction nozzle. I assumed with my pump and motor set up it would be over kill for a 2.5" dredge, but I have to run mine wide open just to get it to function and then it does a poor job on suction. I am using one of those nozzles that has a ring welded at the end to avoid clogs. I have even put duct tape around the opening (sides) to close off and improve suction. This helps a little but not much. You can put your hand to the suction end of the nozzle and "barely" feel any suction. Nothing like the regular suction nozzles I am used too. I am ordering a suction nozzle from Keene shortly and hope that fixes my problem. I run a 1.5" pressure hose to the nozzle and have plenty of water. I even put a big plastic tub (for mixing concrete) at the end of my dredge to catch what blows out, which is quite a bit at full throttle.

Anyway -- best of luck with getting yours dialed in --- it's more fun when they operate properly!

Al

 

[Jason in Enid]

Hi Jason --- I also use a 6.5hp (Honda clone) and Keene's P180 pump for my dredge/highbanker set up but more about my problem later.
..... I do mostly benches and old tailing piles (out of water) and prefer the heavier one for dragging over rocks, vegetation etc.

As for a dampener --- Dollar General sells heavy duty door mats for around $4 which you can cut to fit, They work great for me.

My problem is not enough suction --- I run my dredge (2.5") with a suction nozzle.

Anyway -- best of luck with getting yours dialed in --- it's more fun when they operate properly!

Al

Thanks for the tip about the DG mat, I'll go look at them today. I agree that the heavy duty hose will take 100Xs the abuse the normal suction would. Mine could be workable if it wasn't trying to permanently curl. I can't pull it straight.

I think you have a problem if you have suction problems with your pump and motor. Your pump should be capable of pushing 90psi and 300gpm. Even necking it down to 1.5 inch should still be more than enough water. If your new suction nozzle doesnt cure the problem, I suggest opening up your pump housing. You could have plugs in your impeller vanes.

I'm also a little unsure what you meant by using duct tape to close off the sides? If everything is connected properly, then there should be no need for duct tape except to cover hose clamps so they don't tear up suits and skin.

 

[Al(GA)]

Thanks for the tip Jason --- I will check the impeller vanes for blockage. Hope that's the problem because it's cheaper than a new nozzle
Do a search on e-bay for suction nozzles and you will see the type I have (with welded ring at tip and open space on the sides).
Something I do with new suction hose --- I have a wrap around porch at my place and I put one end between the pickets, then stretch it out straight and put the other end between pickets. Let it set for a week or two in the sun and it eliminates the curling for me. Might be worth a try before buying new hose!

 

[Jason in Enid]

Oh, I understand what you mean about the sides. That shouldn't be an issue. Who made the nozzle you are using now? There are a lot people producing crap to sell that has no engineering or design testing behind it.

It could also be that you have leaking seals or connections in your pump. Lots of possibilites and you just have to start testing and replacing until the problem is solved.

 

[okbasspro]

Hi Jason --- I also use a 6.5hp (Honda clone) and Keene's P180 pump for my dredge/highbanker set up but more about my problem later. As for suction hose, I use two types (1) a heavy duty type, I buy from Industrial Supply Inc. in Bellingham Washington (they sell on e-bay). (2) Keene's suction hose is lighter weight and more maneuverable. Both have smooth insides and would prefer Keene's when working in streams. I do mostly benches and old tailing piles (out of water) and prefer the heavier one for dragging over rocks, vegetation etc. As for a dampener --- Dollar General sells heavy duty door mats for around $4 which you can cut to fit, They work great for me. My problem is not enough suction --- I run my dredge (2.5") with a suction nozzle. I assumed with my pump and motor set up it would be over kill for a 2.5" dredge, but I have to run mine wide open just to get it to function and then it does a poor job on suction. I am using one of those nozzles that has a ring welded at the end to avoid clogs. I have even put duct tape around the opening (sides) to close off and improve suction. This helps a little but not much. You can put your hand to the suction end of the nozzle and "barely" feel any suction. Nothing like the regular suction nozzles I am used too. I am ordering a suction nozzle from Keene shortly and hope that fixes my problem. I run a 1.5" pressure hose to the nozzle and have plenty of water. I even put a big plastic tub (for mixing concrete) at the end of my dredge to catch what blows out, which is quite a bit at full throttle. Anyway -- best of luck with getting yours dialed in --- it's more fun when they operate properly! Al

Al check your pump I use a 2" trash pump on a 2.5hp clone and have enough suction on my 2.5" dredge to pull your gloves off.

Plugged
Air leaks
Wore out

 

[Al(GA)]

Thanks for all the suggestions guys ---- The pump (Keene P180) is new with less than 30 hours on it. I disassembled the pump and the vanes are super clean (no blockage). It seems to work fine (lots of water output) and I do not see any leaks (hoses are fairly new also, along with a new foot valve). I ordered a new suction nozzle from Keene today and will update my experience when I try it out. Also the engine is fairly new (less than 60 hours) and works well.

 

[russau]

Plugged
Air leaks
Wore out[/QUOTE]
YEP! Im all of that!

 

[ncclaymaker]

Had a similar problem... turned out to be vegetation particles, grass stems, and general small flotsam getting past the store-bought suction strainer. I balled up the suction strainer in some window screen material and fastened it securely with plastic cord. These centrifugal pumps don't require a substantial amount of foreign objects to degrade their performance. Check the intake for the performance problems, it's usually there.

 

[Al(GA)]

Problem solved (poor suction --see previous post in this thread) ----- The new Keene suction nozzle did the trick, it is WAY BETTER than the other suction nozzle I had. I don't like to bad mouth others (why I didn't mention what company I bought the other nozzle from) but I went through two of his, with lots of frustration. The first one didn't work at all and the second (tested by mfg. before shipping) was so-so. The keene one is night and day better. Glad to have my problem fixed and a heads up for folks wanting to try the ringed suction nozzles made in CA and sold on e-bay.

 

[nh.nugget]

Beware of cheap imitations!

 

[okbasspro]

Had a similar problem... turned out to be vegetation particles, grass stems, and general small flotsam getting past the store-bought suction strainer. I balled up the suction strainer in some window screen material and fastened it securely with plastic cord. These centrifugal pumps don't require a substantial amount of foreign objects to degrade their performance. Check the intake for the performance problems, it's usually there.

glad you got it figured out now time to start mining.