Shaker table question

[G1sammons]

HOw much throw should a table have ?

 

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[Jim in Idaho]

About 1/2", but on the one I just finished, the table movement is adjustable. I can adjust the amount of movement, the bump intensity, and the speed. Also can adjust the amount of water flow, and the table tilt in both directions.
Jim

 

[G1sammons]

Thanks Jim
Does it need to be adjustable? The throw ? I had already plans on adj tilt

 

[Jim in Idaho]

I think it does. I know speed makes a huge difference, so I imagine the movement also makes a substantial difference. Until you run YOUR material, you just can't predict how it's going to act on the table. I don't have any cons, so I haven't run mine with gold yet. It will be interesting to see how the various adjustments affect the cons.
On my design, the bump is generated by the table stopping before the activating rod reaches the end of it's travel. If the table stops earlier, the bump increases. So a simple bolt stop for the table adjusts the bump. The return spring tension adjusts the table movement distance. These adjustments are somewhat affected by the speed, too. For a faster speed, the mainspring tension needs to be increased, so it follows the cam profile closely even at the higher speed. That requires the return spring tension to be increased if I want to maintain the same table travel. It's all interconnected, and takes some fiddling to get it optimized for the material you run. That's why tables are usually set up and left alone...they don't make a good portable unit.
Jim

 

[G1sammons]

I think it does. I know speed makes a huge difference, so I imagine the movement also makes a substantial difference. Until you run YOUR material, you just can't predict how it's going to act on the table. I don't have any cons, so I haven't run mine with gold yet. It will be interesting to see how the various adjustments affect the cons. On my design, the bump is generated by the table stopping before the activating rod reaches the end of it's travel. If the table stops earlier, the bump increases. So a simple bolt stop for the table adjusts the bump. The return spring tension adjusts the table movement distance. These adjustments are somewhat affected by the speed, too. For a faster speed, the mainspring tension needs to be increased, so it follows the cam profile closely even at the higher speed. That requires the return spring tension to be increased if I want to maintain the same table travel. It's all interconnected, and takes some fiddling to get it optimized for the material you run. That's why tables are usually set up and left alone...they don't make a good portable unit. Jim

Hmmm I think I'm going about it wrong ! I had planed to just use a crank and rod with a short stroke .. Pulley driving the crank..
Would you mind sharing some photos of your driving system so I might get it right the first time ...
I had it in mind to shake back and forth equally with out a bump in the motion ...
Guess that's wrong

 

[Goodyguy]

Got to have the bump, that's the heart of it.

Just like bumping a gold pan to make the gold walk to the edge.
The gold is heavier so it walks further than everything else after each bump due to inertia.

The tendency of an object to resist changes in its state of motion varies with mass. Mass is that quantity that is solely dependent upon the inertia of an object. The more inertia that an object has, the more mass that it has. A more massive object has a greater tendency to resist changes in its state of motion.


GG~

 

[G1sammons]

How to make a drive unit?

 

[Jim in Idaho]

These tables are complicated. I started on mine in late December, and worked at least 2, and often 3 or 4 hours/day almost very day. I just finished it a few days ago. Ideally, you want a cam. You want a rapid motion in one direction, and a slower motion in the other direction. You also need the bump, as Goodyguy said. I'll get some pics taken, and posted tomorrow. Maybe a video, without water....LOL...it's still cold here.
Jim

 

[G1sammons]

These tables are complicated. I started on mine in late December, and worked at least 2, and often 3 or 4 hours/day almost very day. I just finished it a few days ago. Ideally, you want a cam. You want a rapid motion in one direction, and a slower motion in the other direction. You also need the bump, as Goodyguy said. I'll get some pics taken, and posted tomorrow. Maybe a video, without water....LOL...it's still cold here. Jim

I'm in no hurry ... I just hate to do the cleanup side of dredging so I figured I would try to build a table .. I watched a small tabletop home built one run and I was pretty impressed with how well it did... It pulled smaller gold then anything iv ever seen .....
By the way goody that bumbing thing with the pan I thought that was my secret . Didn't realize that others did that...
No one els,at our camp does it they thought I epwas nuts until they see that gold line form....

 

[Goodyguy]

I learned the technique from Mike Pung the inventor of the Gold Cube, he's got it down to an art form.

Struggled with it for two years until he informed me that I was bumping at the wrong angle. Once I learned to strike the pan downward at the same angle as the side of the pan instead of in a straight line against the pan it all came together. Much easier that way, it looked so easy when he did it that I knew I must have been doing something wrong, so simple of an adjustment but what a difference it made.






GG~

 

[Jim in Idaho]

The way these tables work is like jerking a tablecloth from under a bunch of silverware. The table makes a rapid motion from under the material....the material slides on the table surface. The table returns, softly, to it's original position. The bump is the "jerking" motion. The whole thing repeats. When the table makes the rapid motion, the heaviest material slides the most...or, it stays in its original position and the table moves under it.....the lighter material tends to move with the table, or at least moves more than the heavies during the jerking motion......the soft motion carries everything back to the starting position......so, the heaviest material moves along the table faster and farther, than the lighter material. That means the lighter material is exposed to more washing action by the water, and ends up getting washed off the table sooner than the good stuff.
Jim

 

[Jimmydolittle]

How To Build and Operate Shaker Tables

 

[Goodyguy]

Jimmy,
Thanks for the link


GG~

 

[Jimmydolittle]

There are three parts to this, need to search for the other 2.

 

[Goodyguy]

There are three parts to this, need to search for the other 2.

How To Build and Operate Shaker Tables- Part-I (68 pages):
dl.dropbox.com/u/87555256/shaker-tables-1.pdf

How To Build and Operate Shaker Tables- Part-II (19 pages):
dl.dropbox.com/u/87555256/Shaker-Tables-2.pdf

How To Build and Operate Shaker Tables-Part-III (35 pages):
dl.dropbox.com/u/87555256/Shaker-Tables-3.pdf

 

[jcazgoldchaser]

And dig through this guy's videos, he had one that showed the mechanics, but I can't find it


I like how he can pull the table and use it as a power classifier

 

[Jim in Idaho]

I finally got the video done. It's mainly about the mechanism of the table, showing some of the adjustments, and what they do.

 

[russau]

Jim is the table surface of your design? did you make it?? great video!!

 

[Jim in Idaho]

Jim is the table surface of your design? did you make it?? great video!!

Yup...I flattened 4" ABS sewer pipe in the oven to make all the flat materials. Did the same for my mineral jig. To get the ABS REALLY flat, you have to wait until it's soft, then put it between a couple of 1/4" steel plates and clamp them together. Then you put it back in the oven for a few minutes, and occasionally tighten the clamps. After it cools, it will be really flat. For most uses, it doesn't have to have to be really flat.....but, for the table surface, it does. For the riffles...I cut them on a taper on the tablesaw. I milled shallow grooves in the table surface to align the riffles...then glued them in.
Thanks for the compliment....I hope the video is useful.
Jim