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Gold Prospecting Forums - General => Tech Talk => Topic started by: DharmaSoldat on June 11, 2018, 08:03:06 AM

Title: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on June 11, 2018, 08:03:06 AM
Hi all,

I have built a 3" diameter hand dredge body but have not yet decided on an arrangement or size of valve system.

I wanted to poll you guys to see what you have found success or not success with.

I was initially considering an arrangement like the gold recovery pump with two non-spring-loaded 2" backwater valves, 1.5" hose and 1" nozzle with a tee connecting  everything.

Thanks!


NOTE: I am fully aware of the legalities of hand dreging in BC, for all who are concerned.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: JOE S (INDY) on June 11, 2018, 10:50:46 AM
Say there, Dharma,

You accidentally called those hand operated suction devices a "Dredge".  Some folks do, in fact, call them that but they are NOT a dredge of any sort or description.

There are two general types of "Dredges" - the first is a "Bucket Line Dredge" which is sort of like a chainsaw on massive amounts of steroids.  It scoops dirt from the streambed (and like sawdust) it carries that removed streambed material internally to process it for gravity removal of Gold.

The other type of dredge is a "Suction Dredge" which uses pressurized water to create a vacuum and that vacuum is used to draw up material from a streambed source and then transport that material through a delivery hose to a waiting sluice box.

What you have is a "non mechanized hand tool", an underwater, hand operated, material extractor using hand generated suction.  The device was originally called a "Yabi Pump" and it was specifically designed and used for shellfish harvesting on beaches in Australia.  There have been other names attached to it from time to time, but - and this is important - it s not a dredge of any sort.   <-NO_> <-NO_> <-NO_>  People who make them for sale have, occasionally, and often intentionally, jacked up the buyer's perception of their use by creatively misnaming them a "Dredge".  Nothing could be further from the truth.

Aside from the sometimes intentional misnaming of the tool (usually by those who should know better) the concept works well.  A bit slow in use, but in some cases it is a wonderful tool that is just what is needed.

One problem with their use is the loss (falling out) of the captured stream bed material.  The intake brings material in but as soon as the intake rush stops gravity takes over and the "stuff" falls back out through the intake tube and is lost back into the stream bed.  Two simple 90 degree bends in the suction line allows the barrel to be rotated at the end of the intake stroke, rotating the tip of the intake upwards and stopping slide-out of "Good Stuff".

One way valves have been used in the past but traditionally suffer from ingested objects fouling the sealing surfaces.   <-shock_>  Give it a try and let us know how you do.

So, since you do not have a "dredge" but rather a "Yabi Pump" I wonder if that changes things a bit as to the BC regulations.  I don't know but, well,  maybe .....................................

Joe

Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: mcbain on June 11, 2018, 07:39:20 PM
Hi.Joe nailed it. It is simply a hand operated straw.Check out My Gold Panning.I Have not been in contact with him for 2 years but he was building some very nice units.Randy at * in penticton.bc.Luck Mcbain.

* Mark,  May I suggest the phone number be sent via a PM - a public forum is a scary place to post it.  Moderator
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 15, 2018, 03:47:09 PM
So as it turns out, I ended up building the one-way valved unit at an overall 2" size.

I based it on a 45-degree wye fitting with the 45 degree part facing forward and down. I attached a 90 degree street elbow on the 45 degree part with the end pointing off to the right side and used 2" ABS backwater valves with flappers as the one way valves. The unit attaches to the main suction body with a 3"->2" reducing adapter. The inflow, outflow and suction body reducing adapter are all fitted with threaded adapters.

The design process is a fickle thing.

Some problems and solutions:

The suction nozzle
This is a threaded adapter attached to a 6" piece of pipe, and a coupling at the other end with a 2" drain-screen like thingy. No matter how many holes I drilled into it, it still did not get a lot of suction and was generally easier to get clogged. Instead of this, I settled for a 1/4" head bolt across the suction end with locknuts holding it in place and it works much better.

The goldsucker to bucket hose
I settled on a 1.5" diameter vinyl braided hose with poly adapters with a 2" male thread -> 1.5" hose barb. Suffice to say, it got WAY clogged and just generally was a PITA to clean out as this happened all the frickin' time. If I can fix the valve problems (see below) I will get a 2" PVC thread adapter and bond it to some flex PVC pipe I sourced with the standard cement/primer combo.

The valves
Oh god, the valves. They're the Bow Plastics one you can get at home depot and a number of other places. So they work great except for the fact that the valves stick. Initially I thought I could cure this with a 1/4" bolt and bunch of nuts on the other end to provide some weight, however that still did not prevent the hinge from gumming up with fine sand. I am going to try to put a cap of foam rubber over the hinge and clamp it down with the screw on cleanout lid. Still need to test this out, but it should solve my woes if it works.

So far the suction body with just the bare 3" end has been the best performer so far for shallow water work where a shovel isn't as good, but the valved unit will be better for direct-to-bucket capture in hard-to-reach places.

If anyone has any questions, I'm happy to answer as this has been quite a process.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 17, 2018, 09:38:42 PM
SOOOOOOooooooo.... an update.

Tonight I tried the foam cap idea and it did great for capturing the stuff going on top of the hinge, but there's still an uncovered gap up front and the fine grit cakes in there like nobody's business.

I have to go to plan B, which is to make a rubber flapper to replace the plastic hinged cover. This is made easier (I hope) by the fact that the opening into the valve has a ~1/4" 'gasket area' around the hole and up the side of the housing to where the plastic hinged cover would hook in.

We'll see. If it can continue without fouling it has potential to move a lot of gravel in a short amount of time.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 19, 2018, 04:51:57 PM
Another update...

So with the failure of the original plastic hinged flappers that came with the backwater valve, I got to plan B finally.

After some measurement and materials sourcing - I engineered a foam rubber flapper out of a 1/8" Dollarama Off-brand My Little Pony™ placemat and some Off-brand 3M plastic furniture sliders. With a cap of sponge it holds it in place perfectly and passed the water test with 50 continuous strokes.

Next up: find a harder foam rubber 'cap' to hold the flapper in place, produce a more nicely cut and/or reinforced flapper, then test against them gravels.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: beav on July 20, 2018, 03:13:26 AM
Any chance of taking some pics of what you are talking about and post them on here?
Hard to visualize for us ole' fogeys.
Beav
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 20, 2018, 10:16:01 PM
Pictures? Sure!

Here's pictures of the:

- Whole unit assembled
IMG_1549.jpg

- Taken apart
IMG_1550.jpg

- One-way valve unit detail
IMG_1548.jpg

- Suction nozzle
IMG_1567.jpg

- Suction nozzle guard bolt
IMG_1566.jpg

- The new valve design and foam rubber cap
IMG_1565.jpg
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: suburbanator on July 21, 2018, 04:50:12 PM
I Bought one of the commercially available hand dredges (Mother Sucker).
The one that can snipe or can convert to  pump to a bucket.   I can see its use in some areas,  however nowhere that I go is there really enough gold just sitting 2" down behind some rocks.   Most of the terrain I have experienced so far requires trenching or a fairly large hole to start recovering gold in any quantity.

once some bedrock becomes exposed in Late August,  perhaps this tool might be more effective for me.

Hopefully you didn't spend more than $180.00 building it,  because that's about what they cost online.  The guy has put a ton of time and effort into it and it works fairly well,  sometimes best to suck up the $$.   

When I started I tried to make everything myself... now I prefer just to modify.  Definitely not trying to discourage you however!

Improvements that could be made to the Mother Sucker that perhaps you could consider.

1.  Easier removal of tips for cleaning after sniping
2.  Easier swap from snipe to pumping
3.  Larger reservoir for the material captured when sniping as currently it holds maybe 2-3 cups of material before it needs dumping

Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 21, 2018, 06:48:30 PM
Well Suburbanator, there's definitely no discouragement here :)

The goal for this project was to be able to suck up a lot of material behind rocks and such specifically those underwater or close enough to have shovel holes flood easily and deposit the gravels into a bucket, á la gold'n'sand but with a much larger intake valve, suction force and intake capacity.

I have found it difficult to extract decent gravel without disturbing much of the surrounding material when 8"-10" rocks appear after digging a few inches - especially when those bigger rocks are held tight to the boulder face or 1-2" away.

I tested out just the suction body with a 3"->2" reducing coupling (instead of the one-way valve system) against some gravels in a similar circumstance. The gravels moved really well and it was easier removing the large rocks because the surrounding fine sand was compacted whisked away easier whereas a shovel would be clangin' an' bangin' the face edge against the bigger rocks.

So far, all toll'd, I'm in for about $250, but that's because I also had to buy a lot of the tools and glues and whatnot that I did not have prior to starting.

I have other ideas that I want to do so I figure it's a good investment and building this thing has definitely given me more than $250 of enjoyment as a hobby so... it's all good.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: suburbanator on July 22, 2018, 07:58:31 AM
Well,  if your not to far from me (Langley) your welcome to come check this one out.

Or come up and try it in the field.

Might give you some ideas.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 22, 2018, 05:28:48 PM
So I went down to the creek, found a nice big boulder and tried out the new valves. They work awesome.

I managed to capture half a 5-gallon pail's worth of gravel in a few strokes.

Still have to work out some glitches on the upstroke as it gets pretty tight after a while. I think I just have to find a more optimal 'sock' material to build out the seal (probably one of my old wool socks, to be honest) as the rubber plug by itself has too much friction as finding that sweet spot is a lot of fiddling.

Still does not perform as well as the suction body just by itself. Different purpose - different tool I suppose.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: mcbain on July 22, 2018, 07:37:39 PM
Ouch.Luck Mcbain.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 22, 2018, 07:43:13 PM
What can I say, man... it's a process :D
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: CLHaddon on July 22, 2018, 11:20:12 PM
Dharma I  built my own crevice sucker using similar materials and also found that the rubber on the plunger got really sticky and difficult to use. I had some cheap felt laying around so i just cut a square of that and put it over the whole thing and it works way better. I threw a couple extra squares in my kit because I expect it to wear out. Nice work on the design, way better than mine!
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: beav on July 23, 2018, 03:00:16 AM
Hey DharmaSoldat!
Thanks for U/L'ing the pics. Now I can see things make more sense now.
That's a cool idea using those backwater valves, instead of the normally flow-restricted sump pump check valves.
I think you did a great job on this. At least now you have a basis of something you can perfect and iron the 'kinks' out of.
Kudos!  {cool^sign}
Beav
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: suburbanator on July 23, 2018, 11:28:51 AM
The plunger used on the unit I have is a leather product of some sort.  It requires soaking for a while prior to use.
Your welcome to PM me and come have a look or I can try and send some photos.


Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: beav on July 23, 2018, 04:44:27 PM
Does it look like this?
seal.jpg
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: mcbain on July 23, 2018, 08:19:17 PM
Hi.guys.Rubber is outFelt or leather works the best.Remember the blue felt insoles you can buy for your boots? real cheap about 7.00 bucks for 2.You can make a lot of seals whith those.Just saying Mcbain.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on July 23, 2018, 10:23:36 PM
McBain, that's what I found in my research and testing.

Currently I fit the rubber stopper with a shopping bag that is a fabric material akin to a 'rough silk' or polyester. Works great but I suspect that because of the volume of material it is causing stroke issues and also makes it difficult to get the end cap off.

I figure using one of my old wool socks should do just fine between forming a good seal and reducing friction enough to make it easier to handle and not stick as much.

Jokes aside, I look forward to trying this out @ the creek.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on September 06, 2018, 09:27:58 PM
Been a long time since I rapped at ya...

Gym sock makes an ideal seal around the test plug assembly. The custom valves work great with hard foam seals keeping them in place.

Tests today show it performs great with the 8" nozzle - it would probably perform even better with a shorter nozzle and a better rock guard that wasn't embedded in the centre of the tube - all in good time.

Invested in a 2" MIPT -> hose barb adapter and it works great - going to invest in a relatively cheap shop vac hose to hook it up to a bucket and see how it does with some mid-stream boulders - some of which had collections of old axe heads and such around them.

Cheers



Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on October 06, 2018, 05:16:41 PM
This is my last update.

Bought a 2.5" x 8' shopvac hose from Lee Valley tools and two hose adapters.

Works like a charm and the diameter of the hose and adapters means the lid no longer pops off the 5 gal. pail anymore.

Huzzah!
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on October 26, 2018, 07:42:28 AM
I lied. Sorry guys.

I am back in the lab working on a new valve design using ABS union fittings that should keep the same flow rate within a more compact and cost effective package.

We'll see how this goes.


[edit: the megasucker works fine - I just lied that the previous post would be my last...]
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on November 04, 2018, 06:21:10 PM
Finished the glue work and such for the version 2.0.

Tested it out with some makeshift valves in place - worked decent but has to be primed to work properly. This might not be a problem if I get the valve design right.

Looking forward to testing this out with gravel.

Some pics with inch ruler for scale:

IMG_1784.jpgIMG_1785.jpg
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: mcbain on November 04, 2018, 07:19:14 PM
Hi.You may have figured this out already but shop vac hose is pleated and acts like a sluice.any gold you find will be in thehose.i had the Royal gas powered vac and did not get gold until I flushed the intake hose.All your hoses should be smooth lined.Luck Mcbain.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on November 04, 2018, 07:57:55 PM
Hi.You may have figured this out already but shop vac hose is pleated and acts like a sluice.any gold you find will be in thehose.i had the Royal gas powered vac and did not get gold until I flushed the intake hose.All your hoses should be smooth lined.Luck Mcbain.

Yeah... I have a source for smooth lined segmented hose, but I make sure to flush the lines thoroughly every time I use it...
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on November 25, 2018, 11:32:32 AM
So working on valve section version 2.0...

Two 2" ABS unions and a sanitary tee fitting. These are the latest versions of the valve flaps, which I just finished water testing before writing this post. They're made of approx. 3-4mm rubber sheet (read: a stair tread from Home Depot), some green twist-tie wire and some nut/bolt/washer hardware.

IMG_1804.jpg

Here are some other prototypes (about 9 were made in total). From left to right:
- the first one was a quick-n-dirty made from the same discount my-little-pony table mat material and electrical tape.
- the next pair were made from the same table mat as a backing, some yellow plastic from a binder and a floor slider. They failed catastrophically during gravel tests because the yellow binder material was too brittle
- the last pair were the prototype before the latest version of the  valve flap made from the same rubber, but they didn't have a much output flow as the latest pair and would constantly get sucked out under violent pressure from the outflow union because the circles were cut too small

IMG_1805.jpg

I'm looking forward to gravel testing these latest ones.

More updates coming up...
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: mcbain on November 25, 2018, 06:26:40 PM
Hi.DS I give you a lot of credit for Determination.but every time a 45 or 90 degree angle goesinto the system You have huge losses.Just saying.Luck,Mcbain.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on November 26, 2018, 07:18:43 AM
I hear ya McBain. I tried to pare down the system to the least number of components this time around. The previous one had way more bends in it...

The sucker works at an angle to the ground of around 45 degrees or less, optimally. I've found that it's easier than a shovel and pick at least in terms of sucking up fine gravels especially when there's so much variability in the size of the rocks (from pea size and smaller to fist-size and up to basketball size all in the same cubic foot or so).

Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on December 01, 2018, 08:40:18 PM
Small update. The new valves work great - except they get sucked out because there's not enough holding power between the pieces of the ABS union and the rubber of the valve flap - the outflow valve flap eventually gets sucked into the main body on enough upstrokes.

Possible solution? 1/8" shims cut off of 1.5" ABS couplings and some Shoe Goo to cement it all together.

The urethane is curing as we speak - stay tuned for the next exciting episode.

Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on December 05, 2018, 02:01:31 PM
Okay... so I managed to river test the reinforced valve flap. It works great - and it turns out I need them on both intake and outflow ports as the intake valve got sucked in just like the other one did prior to reinforcement.

Shoe goo and rubber for the win.

Also picked up a third-bucket of gravel to test in my future concentrator project...  <-yahoo_>
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: JOE S (INDY) on December 05, 2018, 02:44:32 PM
Excellent! 
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on December 05, 2018, 04:14:50 PM
Joe, the second reinforced valve flap is curing right now... I have a feeling i'll be able to optimize the flow rate by changing the shape and/or construction of the valve flap.
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: bruno on December 05, 2018, 07:00:33 PM
Dharma, I have used the ABS check valves for my hand suction dredge, They work really wellCheck valve.png
Title: Re: Hand Dredge Check Valve Size and Orientation
Post by: DharmaSoldat on December 06, 2018, 06:06:41 AM
Hay Bruno :)

I had considered those kinds of valves because they seemed cost effective at first but I really wasn't sure of their performance/endurance level or their ability to be integrated into a final design.

The larger 2" valves also cost a lot more and one of my main goals was having as much throughput as possible in the system.

I think (not including R&D costs) that the ABS union valve actually comes under the cost of that one by a dollar or so - which was also one of my goals - to see how cheaply a highly effective valve could be made.

It's still ongoing :D