pump for home made dredge

[nuggy]

OOPS, forgot Box - motor sits on bank or in tube, not on floats with box.

 

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[Jason in Enid]

Your box looks awefully small. Have you actually used it yet?

 

[nuggy]

Your box looks awefully small. Have you actually used it yet?

Hi Jason, this box was once on a six inch venturi dredge! Used as an underwater box it had a lid on it then. Different to the others shown above which are surface boxes, this one needs to be partly submerged, about halfway ( a semi-surface box we call them here). The back pressure slows flow to let heavies drop out. That's why the sides are much higher too. This type of box is not as good as the surface type for catching fine gold, but it takes less power to run, as not trying to lift material so far above surface.

Yes I have used it - On my thread "Let Dredging Begin" is a dark photo showing it floating in creek. The dredge especially the pump goes better than I thought it would.
I made this set-up from stuff I had lying around or bought cheaply, didn't have much faith in the pump, as it's a self priming type, Onga brand. Turns out it has way better pressure than I thought it would, and I will be able to run a surface box on it if I want to. Probably won't spend any more on it, as I'm more used to 5 or 6 inch dredges and moving more and bigger material. Nuggy

 

[Gravel Hog]

Nuggy, I think you did a bang up job, as I said before.
I didn't realize your sluice was off a submersible tube, that is what they are called here.
Looks to be all aluminum construction, did you TIG weld or MIG Spool Gun? At any rate looks good.
Got me thinking, wonder if one could make a bigger dredge similar to yours like say an 8". I have always wanted a mini size 8".

 

[nuggy]

Hi G. H. , thanks for the compliment. Yes I have often wanted an 8 inch dredge - It needs some serious power to make it work though, big a$$ pump n motor ( ow, my back hurts just thinking about it ). I have been trying to find out more about using both a venturi and power jet on same dredge. Seems to give quite a boost to power, pushing and pulling at same time, still going to need a bigish unit though. I don't have anywhere to run a big beast like that now either, but like the idea. Nuggy

 

[nuggy]

Forgot to say, yes it's all aluminium, tig welded, not by me though. I do fabrication and then take it to engineer for welding, dam expensive. Nuggy

 

[Jason in Enid]

A patially submerged dredge.... interesting idea. I'd love to see one in operation some day.

 

[nuggy]

Hi Jason, up above my nozzle pix is a link Gravel Hog put in showing a sort of similar set up - mine just has a little more of the box submerged, and motor sitting on bank. Box on mine not all that small; starts at 8.5 inches - tapers out to 11.5 inch at end. Nuggy

 

[fudnz]

Hell John - I hope that Fulton Hogan dont find their cone :-) This looks better than the one we used a while back... the pontoons look like they are Eldorados - made in Oz -

A bit more Kiwi - ism..... 5" suction nozzle into 6" lift pipe and onto step ladder 'V' box 6' long... great for fine gold as from the time the materials enter the 5" nozzle they are slowing down allowing the real flour fines to settle... and yes there is still sufficient force to kick the rocks off the table...



another shot

Hi guys, Strickmen, Your set up is exactly the same as mine (pontoons, frame & box) except my pontoons are green. I changed mine from a 3" to a 4". Ditched the old crasher box & used an old road works cone to make a flare. You have probably seen these pics before

Have you ever thought of widening the frame a bit so the box can sit lower down between the pontoons? This will give you better suck as the material doesnt have to be pushed so much higher above the water line. Gravity takes over big time when the material gets above the water line & does have a big effect on suction at the business end of the hose tip.
You can see how high my box is sitting above the water. You will notice how much lower boxs sit in dredges these days.

Efret. I actualy wonder if yours isnt too low & by the looks of your frame you are going to mount the motor/pump at the back? If not then I think you will have to slide your box back quite a bit & as has been said you will need to find the sweet balance spot. Also as your operating & your box fills up with water flowing down & the riffles getting loaded up with material, this will affect the balance as well & you will need the adjustments to be easily made out in the field as well as being able to alter the tilt of the box.. You will notice in my above pics how much lower the box is to the water when it is operating & full of water & material compared to the pic of the dredge just sitting in the water before operation.

Nuggy, How you going mate? I was going to go for a dredge this weekend but the weather that has been fine for months has decided to 5hit itself this weekend. BUGGER, so here I am grazing the forums.
Good luck to you all & a very merry xmas & a prosperous new year.

Happy hunting through the festive season

Regards

JW

 

[Gravel Hog]

fudnz, it looks all good.

Question- I see two pumps, it's a 6" ok I get that but is one pumps outlet going into the intake of the other? If so can I ask a friendly why?

I enjoy looking at everyones pictures of their dredge builds, very nice all of them.
If I could just get some of my photos scanned I would share some, too. My 8" build was a beast.

 

[strickman]

looks like a suction nozzle with a venturi also . pushes and sucks , should be a strong setup.

 

[fudnz]

Hi guys - It is just a single suction nozzle venturi - i found that by using one pump as the lift and feed to the second i was able to obtain full pressure from the second high pressure pump - nothing lost in the lift of the water to the pump. The gain was around 10% and at the top end it was quite a bit when the nozzle was getting to around 5 or 6 foot down.

I am now powering it with a 'Proline' HP300 pump - it is able at its top end to deliver 280 gals at a pressure of 55psi and running this through a 7/8th venturi gets it going good. I had a keene P180 on it - it worked but not real good - you had to limit what was going up the hooter or it could stall - The pump in the picture with the two pumps - the first one is a chinese 2" cetrifugal 'water mover' - they have a 25psi rating at 3600 revs - I import these pumps in from China and sell them here in New Zealand along with a bit of other gear. I have done this for over 8 years now. The high pressure fire pump honda lookalikes that some of you have are a good pressure pump but dont have the volume to back this pressure up.... The single impellor models have a purported pressure rating of 70psi and the twin impellor twice this at 140psi. I have one of the twins pumping water to 95 metres albeit not a great flow at this height but a flow never the less. I did try a twin impellor on this dredge - no success.
The second pump - the blue one is a copy of the 'Treasure Emporium' made and sold by 'Gold King' in the states a few years ago. A guy here in Christchurch NZ made some patterns off one and produced them under the name 'Swimjoy'. They are a good little pump and have a rating of around 55psi.
Talking with Jeff Kuykendal from Proline - he told me his dad worked for Gold King and this pump was known as I think he said the 20 by 15. Having the Proline agency here in NZ gives me the flexibility to be able to try out the Proline range of pumps on my old 5" 'gumbooter' as I call it. :-) - It has been very interesting seeing how the 300/350/400 pumps go on the 7/8th veturi. I have got one of the HP500's fitted to a 9hp ready for a try... might be a bit of overkill but it might just do the job at a lot lower revs... time will tell.

Here it is again with the P180 on it -

 

[kiwi jw]

G'day Allan you bugger, Happy new year. Good to see you on here. Good bunch of blokes on this site. My 4" above is exactly the same set up & in exactly the same spot that you have had a play with it when you were up here on one of your visits. I had been looking for a pic of your set up in my files but couldnt find one. So bloody good timing. Yours works a treat that is for sure. Hope you dont mind me putting this ugly bugger photo up with with the fine gold it saves.

I am heading off up the Coro for a dredge today for a few days. How was the Nevis?!!!! ! You never reported back to me. Oh....I know ....you struck it RICH & are keeping a low profile.

Take care & happy hunting

JW

 

[Gelmac]

Nice setup ! this is an old thread, so the link to the pump has gone

Still looks Cool !

 

[Gelmac]

Hi Jason, this box was once on a six inch venturi dredge! Used as an underwater box it had a lid on it then. Different to the others shown above which are surface boxes, this one needs to be partly submerged, about halfway ( a semi-surface box we call them here). The back pressure slows flow to let heavies drop out. That's why the sides are much higher too. This type of box is not as good as the surface type for catching fine gold, but it takes less power to run, as not trying to lift material so far above surface.

Yes I have used it - On my thread "Let Dredging Begin" is a dark photo showing it floating in creek. The dredge especially the pump goes better than I thought it would.
I made this set-up from stuff I had lying around or bought cheaply, didn't have much faith in the pump, as it's a self priming type, Onga brand. Turns out it has way better pressure than I thought it would, and I will be able to run a surface box on it if I want to. Probably won't spend any more on it, as I'm more used to 5 or 6 inch dredges and moving more and bigger material. Nuggy

Very old thread I know
Is that dredge you're reffering to is what is called sometimes A (Suitcase Dredge) ? if so how did you find it, do you own that dredge anymore. Would like to see more pics of it if possible .
You did a great job by the way