Saturday, July 12, 2008

Placer Mining Equipment: the Rocker Box

Placer Mining Equipment: the Rocker Box

For those of you who are newcomers to placer gold mining you may not know yet that a gold pan is not a piece of mining equipment but a mining tool meant for sampling, testing, and cleaning up gold-bearing concentrates. A true piece of mining equipment is meant to process larger amounts of gold-bearing material or gravel at increased efficiency (and less wear and tear on you) than panning all day.

One of the most basic pieces of placer gold mining equipment is the rocker box (also known as a "miner's cradle"). It's not known exactly when this piece of rudimentary placer mining gear was first used to recover gold, but early placer miners in Virginia, Georgia, and North Carolina used the rocker box in their home states' gold-bearing streams before bringing early versions with them to the rich California goldfields of 1849-1855.

Here are some salient features of a well-constructed and properly used rocker box:
  • Extremely portable and can be moved easily from location to location.
  • Needs very little water to operate and that water can be reused or recycled (see schematic below).
  • Less strenuous effort required on your part than gold panning.
  • Greater volumes of gold-bearing material can be processed (2-3 times that of a good gold panner in the same period of time).
  • Excellent gold trapping efficiency, even with fine or flour gold.
A common rocker box design consists of four main parts:

1) Sloped, riffled sluice box type body with gold-grabbing indoor/outdoor carpet (or similar material) lining the box underneath the riffles, a handle attached to one side, and two crescent-shaped rocking arms underneath the box;
2) Removable, recessed "hopper" or classifying screen (typically 1/4"-1/2" mesh);
3) Hopper or "feed" box; and
4) Long-handled water dipper or "scoop."

Here's how the rocker box works:

First, the miner shovels gold-bearing material onto the removable hopper screen, uses the water dipper to flush all the dirt, clay, and gold off the out-sized rocks and gravel into the hopper box, and "rocks the cradle" side-to-side while continuing to flush water through the hopper and down the riffle box.

Next, the hopper screen is removed, the waste rock and gravel is tossed aside, the hopper screen is re-inserted into the hopper box, and the entire process is repeated until the riffles start packing up with gold and/or gold-bearing black sands called "concentrates."

Finally, the miner performs a "clean up" by flushing or transferring the concentrates from the riffle box into a 5-gallon bucket or gold pan and then panning the concentrates and recovering the gold. (In more "sophisticated" versions, both the riffle tray and the gold-grabbing carpet lining the bottom of the box can be removed to facilitate easier and more efficient clean up.) That's essentially it.

Rocker boxes are amazing little machines in their overall simplicity of design and function, and they are very good at trapping even tiny bits of placer gold if used properly (the 49ers loved them and used them extensively during the early parts of the California Gold Rush). Additionally, a rocker box requires very little expense or material outlay, nor do you have to be a journeyman carpenter to construct one.

A well-constructed rocker box should be part of every small-scale or recreational placer gold miner's arsenal of mining weapons. Why not build one for yourself and try it out.

(c)  Jim Rocha (J.R.)  2008

12 comments:

  1. Thanks posting this JR.

    After reviewing everything I could get my hands on before constucting my own rocker box, it seems that the apron of this piece of equipment is one of the most important parts of it.

    Just wondering if any of you rocker box users had any hints for apron construction. Currently I have two different apron prototypes to try, but looking for ideas as to construction and materials to max gold collection in this part of the rocker.

    Would truely welcome any input that would save me having to reinvent the wheel in reguards to a good apron.

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  2. Thanks for commenting and asking this pertinent question. In the one rocker I built and used for many years I used heavy canvas (duck) for the apron. It will wear out after some heavy use, but it is fairly cheap and easy to replace. The oldtimers (the 49ers and miners in the latter 1800s) used this approach. But I've also seen aprons that used denim (yep, you heard right...like jeans!). It's your call really, but if you're looking for function as well as tradition...try canvas.

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    Replies
    1. Im looking to build one of these rocker boxes is there a place i can get plans for one

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    2. If you take the time to do a bit of research online, I believe you can find free plans for a rocker. Also, many plans can be found in various prospecting books you can purchase. Also check the Canadian Gold Prospector's Forum (http://gpex.ca/index.php?ind=topsite) Best, J.R.

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  3. Thanks JR

    I'm willing to bet that some gals I know, on seeing some of my old jeans get recycled will be over joyed at not knowing the color of my underwear!

    My current set-up uses a two pocket apron where each pocket is about 5 1/2" long. The one in the above illustration looks to be a three pocket, I'm tempted to slap a three pocket together narrowing down the area that my tailing have to escape at the bottom.

    I've heard at least one guy say that going to a three pocket helped him out. Just wondering how narrow I can make my apron pockets and still process material.

    Come on folks...what does your apron look like and why do you think that configuration rocks so hard for you?

    If in fact that rocker of yours kicks butt, and the bottom of your rocker is pretty much an after thought in gold collection. I want to hear about this beast, along with it's care and feeding.

    Rock On!

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  4. Too narrow a pocket and you'll get clogging...to wide and too much the other direction...lots of times you just have to experiment and then refine your construction after seeing how the unit actually works. But there should be some oldtimers out there who might want to pitch in and give their opinions...and please feel free. At any rate, I wish you well...the rocker box is probably THE MOST historic and traditional piece of mining equipment out there. J.R.

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  5. The best results I ever got was with an apron made where the canvas was loose on a wood frame so that it had a big sag in it. It worked much like a gold pan and caught most of the gold before it ever got down to the bottom and the riffles.
    Also, the hopper bottom should be made of punched or drilled holes in steel plate and not any type of screen wire. The hopper also needs to fit loose in the rocker so it slides and bumps side to side as you rock the cradle. This allows the material to be scrubbed breaking up the clay and clods better. Another important part of running a rocker is the way you rock it. Load the hopper with material then hold the handle with your rocking hand and your water ladle in the other. You start rocking and pouring water at the same time. If you stop pouring water or stop the rocking you must empty the apron in a gold pan and scrap all the material from the riffles and throw it back up into the head of the box where the material leaves the apron. What happens when you stop pouring water or stop rocking is that the material packs up. If you start rocking again without emptying the apron or cleaning the riffles is that the gold has no place to settle and will go out the end of your rocker.
    Good luck!
    Rattlesnake Jim

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  6. Great information for all to read and keep. Thanks Rattlesnake Jim! Jim Rocha (J.R.)

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  7. Thanks Rattlesnake Jim, I've ended up using a inclinometer used for setting up satellite dishes iron plate used for sorting "YES" works well.

    I get in a spot with gold deposits I'll be hitting it big, running two pocket capturing iron deposit material.
    My pockets are full of black sand and iron. My Rocker works all I need is GOOD GROUND.

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  8. The slapping of the hopper against the sides really helps to breakup,loosen and keep material in suspension. Originally my hopper rode on threaded rod... and in my case generated too much friction I should have used smooth rod and threaded the ends as needed, as it was I enclosed my threaded rod in smooth tubing.

    Having run my rocker with, and without the hopper sliding freely. I'm of the opinion that the vibration of the hopper striking the side of the rocker, was an element that when missing really hindered it's ability to sort material.

    I've grown to love my little rocker box, and the ability to operate it where a supply of water is somewhat limited.

    Thanks Guys the tips here have been priceless!

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  9. Thanks for the comments and letting us know how your rocker is working for you. The oldtimers knew their stuff and the rocker was one of their early work horses. Jim

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