Its a pretty cool build for just stuff laying around.
Might I suggest adding some grizzlies over the expanded metal though? Place it at about 2" high at the back and angle it down to about 1" in the front. You don't want clog ups because the front is too low.
The reason for this is so that you don't have to use so much angle to allow the hopper to clean itself out, or at a lower angle scraping all the washed material out.
The added grizzlies will allow the washed rocks to slide on out to your lower grizzlies without getting stuck on the expanded metal.
This allows the expanded meta, moss and carpet to do their jobs unobstructed.
Here is a quick and crude side angle mockup to show what I mean.
Of course the angled bar is the row of grizzlies and the green is the moss.
The front of the bars are way too low in this sketch but its 4am and on the fly.
I recognize that unit(and the voice). It's one of D'arcy Cooper's 1st designs. He's changed the design quite a bit since then. Go to his You Tube page "Miner or Bust" & watch his videos for the updated version. Same style but lots of changes, all aluminum. He was retailing them. Not sure if he still does. Fun video series of his last few years prospecting & sampling, mostly with his highbanker, on some large claims he has in BC. I believe he is going into production machine mining this year.
What I see is a clogging waiting to happen. You have way too much going on in your header box. The expanded metal is going to slow down your material too much. The miner's moss below is making it worse. You are going to have a muddy, possibly clay filled header box in no time. You should do a slick plate in your header box. That will get material moving. If you don't get a slick surface going, you are going to spend more time cleaning the header box out by hand than you will shoveling. Once you get that tested and fixed, then you will need to look at the transition zone between your header box and the sluice. Over the internet, it doesn't look like it is going to work. It looks like it will boil over, and force a portion of your grizzled, or screened material over the sides of the machine before it gets down the sluice. You could fix that with longer grizzly bars, a deeper drop to the sluice, or lower water. But, water depth is going to be predicated by what the sluice box will require to move material efficiently, and keep the riffles clear. Clogged riffles won't do you any bit of good. Or catch anything.
So, in summary, take out all the layers you have in the header box, then give it a test run. Look for how quickly the riffles stack up with material and clear out. Then, if that works well, look at how much material you are loosing out the sides at the header box/sluice transition.
Take this all with a grain of salt, and if any others have differing opinions, please chime in. I am only living by Hoser's life's story.
Thanks for all the tips. This actually isn't me design. I'm running a home made sluice/bucket hopper with a punch plate (1/4" holes) for a grizzly. I wanted to take the bucket out and put another sluice on top so it's kinda like a double decker. I wanted to change out the bucket hopper for something else, so I searched the Internet and found D'Arcy's design. I was going to modify it a bit so it looks like the picture below. Both sluice's will be 3' long. I understand what your saying about the pay getting clogged in the hopper, so I was going the leave the top portion where the spray bars are bare as a slick plate and add the minors moss/expanded metal (1/2" raised) on the bottom 12-18". Then down to the sluice on the bottom (3/4" expanded metal/minors moss/v-mat) with the gate on the end as a dam. My area has a lot of fine gold and this is why I wanted to add the matting I the top sluice because I thought it would increase my recovery of the fine gold.
That sounds a lot better. I have a highbanker I bought here at the house. It has a purely slick plate, but right in the smack middle, it has a perforated section that allows heavier material to drop through. This drop through area settles into a small drawer that is lined with vortex matting. The drawer dumps out to the sluice. The drawer is only to catch what "may" settle out of the header box, and also to give an indicator of how the ground is running. That sounds like what you are really trying to do. When you get to fabrication, bounce the ideas off of us.
Its been interesting to watch the evolution of his highbankers over the years from an idea using scrap to a really nice retailable unit. Like Reedentuon, he's designed what works because he is first & foremost a working miner.
Hey there. Can someone explain to me what a revers riffle does in the bottom run of a highbanker. How it benefits the design. Also, what is the purpose, benifit and set up of a punchplate at the top of the bottom run of a highbanker. What do I put under it.
A punch plate is another classifier and it allows a place for fine gold to drop out...as for what to put under it, varies , but usually miners moss, ribbed carpet and expanded metal over either one. I usually go with moss and expanded because the flow under a punch plate is slower than the rest of the sluice.