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bjvoor
19:27:35 Sun
Jan 20 2013

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Building a shaker table

I'm in the last stages of building a small (2' x 4' deck) shaker table and am having second thoughts about some design details:

1. Many plans (most) have a rotating eccentric (sp?) bumping the table (about 200 rpm some recommend (?) - another question: optimum bump speed). This design is, of course, reasonably easily implemented - but is it the most productive?

2. It would seem to me that a "hard stop" at the one end would be more efective (but more stress on the mechanism). Opinions?

3. Some tables have raised strips (1/4" x 1/4" or 3/8"x 3/8" for example) to guide the gold flakes. Some designs taper these strips. Some have routed grooves instead of the raised strips. Are there functional differences (for different kinds of raw materials as input or different mesh gold in the input for example) or is this just "voodo" design for differentiation for commercial marketing purposes?

I'm building my deck so the table top can be replaced - (plan to build a "wave table" type top sometime in the future - and use the same shaking mechanism) so I could try different table design strategies if I knew what to look for.

4. I'm using a heavy duty 1/3 horse 1700 (approx.) motor - is that too small? I have a 1 horse but that seems like overkill.

5. And lastly... probably many issues I haven't thought of that I would happily receive comments on!

I am a hobby prospector and live in an area with mostly very fine gold (north-west Utah).

  
baub
01:32:12 Mon
Jan 21 2013

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Re: Building a shaker table

Some of the newer sluices have the drop riffle design. The theory is that gold would have a harder time climbing out of a groove than washing over a ridge. Their are some tables that have grooves and they are high end tables. This might be something to check out. If it's true and can be simply duplicated, then that might be an option.
b

  
geowizard
18:40:15 Mon
Jan 21 2013

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Re: Building a shaker table


:welcome:

I would recommend using the search button (above).

Select prospecting forum and 5 hours ago and older. "shaker table" turns up posts going back to 2009. There are posts with links to plans and you tube videos on DIY shaker tables.

Good luck!

- Geowizard

  
popandsonminers
02:03:00 Tue
Jan 22 2013

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Re: Building a shaker table

Bjvoor,

About 5 years ago, I set out to build a shaker table- sounds pretty simple, right? As you’ve come to learn, there are as many ideas about how they should work as there are people to run them! I think shaker table design is about half science and half voodoo, as you say. Everyone claims their's is the best!

It sounds like you still have decisions to make about riffle size, number, type, etc. and the design of the bump mechanism. Also, the orientation and material for top and riffles. I’m not sure how much research you’ve done, but sometimes you just have to try something and see how it works. Oscillations per minute, for instance, are easy to change with different pulley sizes, or with a variable speed motor. Your 1/3 hp motor is plenty big if that’s what you want to go with.

How are you going to use it? The commercial tables are divided into “production” tables, usually for ground whole hard-rock ore, and “finishing” tables, used to process concentrates from either hard rock or placer. Presumably, as a hobbyist, you’re more interested in a finishing table for your fine gold, which means grooves, or short riffles (~1/16” to 1/8” high). Riffles are tapered toward the concentrate end. Screen to 16 mesh or so (window screen) for the table and pan out the larger fraction.

Search YouTube for Gemini Table, concentrating table, gold ore processing, wilfley. Gemini produces the cleanest gold I've seen. Also Google concentrating tables and read some of the early 1900’s texts- they are fascinating to anyone obsessed with shaker tables. If you can get Taggert's Handbook of Mineral Dressing, it's a wealth of knowledge on tables and so much more. The Holman-Wilfley website has some good tutorial info and the Deister Concentrator site does, too. The ICMJ has some ads from present-day fabricators that have useful websites, too.

Good luck! I’ve built a number of tables and used others so I know a fair amount, although am by no means an expert. I’m just now getting ready to build the next “new and improved” version to go along with our jaw crusher and impactor for gold ore processing. More from the Popandson R&D department! I’ll report here when were a bit further along.

And we’re looking forward to your progress reports, too----- Any pictures?

  
baub
14:30:03 Tue
Jan 22 2013

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Re: Building a shaker table

If you look at this as an experiment, you should control all the variables that you reasonably can do in an actual use scenario. If you establish simple guidelines for your testing, these should be ones you can duplcate in the field. Ones that Mr. Wade who made the rp-4, suggested were: use classification, a wetting agent and a secure mount. I might add warm water if possible.
These will reduce your variables to more manageable levels.
A few years ago I took my table to the woods to do local cleanups. I secured it to a trailer. the trailer to a tree and took the remaining slack out by tightening the hitch with the truck. Very stable.
One thing I did not do was adequatly clean my recirculated water well. There was some slimes that interfered with the fine gold recovery. Something else to consider, but an easy fix.

b

  
LipCa
17:28:09 Tue
Jan 22 2013

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Re: Building a shaker table

You said you are in the "last stages" of building...

What part of the build is "firm" so that one can build answers on that?

  
bjvoor
14:01:39 Wed
Jan 23 2013

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Re: Building a shaker table

I have a welded steel frame - 2" square tubing - approx. 36x18x14 high - with wood-and-angle suspension mounts at either end.

I've mounted the 1/3 hp motor (1" pully).

Mounted an 11"pully on a secondary shaft.

Have the mounting brackets for the deck-moving shaft.
Am using (have mounting brackets attached) 2 sheets of polyethelene as my suspension/flexing system - approx. 12-14 inches high - to provide a reasonably "Slackless" motion system - only smooth back-and-forth with no side-to-side.

Am adjusting "tilt" of the table top by tilting the whole machine - with heavy duty long carriage bolts at the widest points of the steel frame. I decided to tilt the whole thing to reduce mass of the table.

Am set up to build deck(s) of glass/epoxy (won't absorb water) - foam core - glass/epoxy sandwich - vacuum bagged to a large sheet of plate glass for a very flat and smooth finish on the upper surface of the deck. I've made test pieces to prove to myself that I can build whatever final deck I decide on.
The deck-to-suspension design allows me to interchange decks - I plan to build a "wave table version" some time.

I reason (good idea or not?) that the less "sprung" mass I can get will allow the table to move crisply - reflecting whatever motion I want the motion system to impart.

The whole thing can be mounted - clamped rigidly - to a steel underframe that will be held solidly (I hope) with bags of sand to cut down on the thing "walking around".

I HAVE been trying to do my homework - so that my questions to you guys are not just "hot air" - and thoughtful advice will be appreciated and used.

My main concerns now are:
1. "bump" (rotating "thumper") or "bang" (hard stop at one end) motion??
2. Ridged (RP-4) or grooved (Gemini) table top? (for a start, at least: a 2x4 epoxy deck is a LOT of work, time, and expense and I am kinda "anal" about trying to get things "right" early on if there is a "right" known out there.)

Popandson (thanks!) has answered the question of motor size (for now at least).

I'm sorry for not outlining this all in my first post - I'm a hunt-and-peck typist and this much writing was PAINFUL. Please excuse the inevitable typo or two - I've tried to proofread (I'm a retired shop teacher who is married to an English teacher) but "stuff happens".

  
LipCa
17:30:10 Wed
Jan 23 2013

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Re: Building a shaker table

I have an RP-4 table and, if your is going to be anything like that(and it sounds like it might be), It will not work correctly with sandbags. I tried that with mine and it wouldn't work correctly. Did for a few minutes until it displaced the sand.
I bolted mine to a concrete slab set inside of a concrete floor so the whole floor did not vibrate.

I've run across several operations in the field that had used tables and they all had concreted the legs in the ground.

Not sure about using wood for mounting?

Why the foam core?

  
popandsonminers
17:58:16 Wed
Jan 23 2013

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Re: Building a shaker table

Yes, I can see you’ve done your homework. And the lack of available information for the nuances of building your table have driven you here for answers. I hope that I, and others, come thru for you. See my reply to your questions, below.

My main concerns now are:


1. "bump" (rotating "thumper") or "bang" (hard stop at one end) motion??

I can’t help you here, as I don’t use a bump system. If you do use a bump system, however, I believe your structure (2 x 2 tube) is more than adequate to take the stress. I also use flat springs as you’ve described- mine are cold-rolled steel. You can eliminate the bump or thump if you tilt your springs backward (against the forward flow of the slurry) about 15 degrees, and oscillate at about 220-250 times/min at ½” displacement. This is like a vibrating conveyor and makes for a very simple system.

2. Ridged (RP-4) or grooved (Gemini) table top? (for a start, at least: a 2x4 epoxy deck is a LOT of work, time, and expense and I am kinda "anal" about trying to get things "right" early on if there is a "right" known out there.)

Your kinda on your own, here. I like grooves, due to the fineness of our gold and the performance of the Gemini table. But, I may try short riffles on our next table to make a comparison. From your description, your final product will be truly an elegant piece of craftsmanship. However, it took me countless iterations to refine my table top layout, so for now, I suggest you do some low cost (time and money) prototype work. Use a sheet of 3/8” or ½” plywood for your deck, cover it with rubber sheet (EPDM pond liner material) and super-glue on some riffles of the style and orientation that you envision. Or get a sheet of poly (or marine grade plywood with several coats of urethane finish) and route in some grooves. The trick is to get the gold clean enough to satisfy you, with no values in the tailings. Make as many tops and revisions as it takes to get it just right- then do the glass-epoxy-foam core-vacuum molded version?

During your prototype stage, you will also evolve your designs for the slurry feed mechanism, the water dressing system, and the launderer layout. This will help you zero in on a more-perfect final design.

A counter-weighted pulley will work fine. I use a direct drive from an eccentric on a shaft (crankshaft) thru a connecting rod to the table. This provides positive table motion, regardless of how much weight is on the table or how much the table weights. Once you get your table tuned, however, the counter-weight system will work fine, as your slurry will not weigh that much.

My research and in-the-shop R&D has certainly given me an appreciation for all those that went before us to develop the “perfect” shaker table design. Trouble is, there is no one-size-fits all. In fact, I believe there are some commercial tables out there that have very poor performance! So, it’s not that easy, and I encourage you to experiment heavily before you build your final design. We're all most interested to hear of your progress and see some pictures?

  
bjvoor
05:51:23 Thu
Jan 24 2013

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Re: Building a shaker table

Thank you all!

LipCa: Thanks! Concrete would be best - I can see that! and the sand will shift, I can see that, too! I was hoping to figure out some sort of more portable (movable) system. My heated garage needs a car in it every once in a while (not for parking - for repair) and so I'm fighting drilling and anchoring in there but it may be inevitable: weather is not good for doing this outside now - and I'd like to have a system I can take to club claims on the weekends - so some kind of "transportable" would be useful.

Popandsonminers: Thanks also for the very useful comments!The foam core deck was my best try at smooth, flat, strong, and low mass (low inertia). My thought was that a "responsive" table might be a real asset. Plywood (or?) that is flat (3/4" ?) and won't warp is HEAVY especially when you add sides, plumbing (could be "unsprung" , too I admit), etc.

The gold recovery channels and waste channels don't need to move - so weight is not an issue there (and if the "engineer" is clever could be reused with a replacable deck system for different design experiments). If I post some drawings would you guys comment? - It's a job for another post on another day, though.

  
popandsonminers
07:35:47 Thu
Jan 24 2013

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Re: Building a shaker table

Yes, be glad to comment on your drawings----

The weight of the table top is really not an issue, altho light weight is good for hiking it into the bush.

I once built a table that had a 30 or 40 pound table top mounted on plate springs like we're talking about. The motor and counter weighted pulley were mounted on the bottom of the table top and oscillated with it. It worked fine, because the natural frequency of the table, with that spring stiffness, was about 250 oscillations per minute. It doesn't take much to keep a table going at the natural frequency, kinda like pushing a kid on a swing- you just need to give it a little push at the right moment.

The more weight in your table top, the stiffer your springs need to be for a given frequency and displacement. That means more springs or shorter springs. If they're too short, they fatigue-crack after awhile from overstress in bending. The stiffer the springs, they more counter-weight you need to get the displacement. Hence, the need to "tune" your system during prototyping, pretty much by trial and error, or copy a system that you already know works.


  
bjvoor
05:03:51 Mon
Jan 28 2013

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Re: Building a shaker table

I found a current source for Gary Weishaupt's papers on building and operating Shaker Tables. The original sources posted elswhere on this forum don't exist any more. They seem VERY authoritative, if not quite complete (by his own admission). They have given me pause about some of my plans - and reinforced others.

http://goldcountryoutfitters.com/shaker-1.htm

I'll post with pictures when I have a working machine.

Thanks to all!

  
popandsonminers
20:09:22 Mon
Jan 28 2013

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Re: Building a shaker table

Yes, that's a very excellent resource-- Good luck on your build and can't wait to see the outcome!!

  
Gani24
21:12:50 Wed
Jan 30 2013

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Re: Building a shaker table

I am also very curious to see the progress you make on this interesting project. Please keep us updated on this pretty lil table you're building.

I am also considering building a small shaker table, so far, I only in the collection of the parts stage. I intend to use Gary's plans.

I have this idea , can I use a sheet of plywood as a mold for deck by shaping the deck surface with riffles like Wilfley type or route grooves on the plywood like the Gemini type and then cover the deck with Truck bed liner (like for example Rust-OleumTruck Bed liner/Coating) then when the liner/coating gets settled , remove it from the plywood surface which produces a deck surface shape similar to the aforementioned brands, how about this concept? can it be done? what is your thoughts about this idea?

Just try to make some improvements here and there.
:smile:

  
baub
01:12:36 Thu
Jan 31 2013

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Re: Building a shaker table

Might consider plexiglass or another stiff plastic like it for the routing . The wood would pickup moisture after a while and warp.

  
Gani24
17:31:30 Sat
Feb 2 2013

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Re: Building a shaker table

baub, I think you didn't get what I meant to say (may be I am not very clear in explaining the concept I proposed).

Here I put it in another way:
Make Fab/Route the plywood surface deck as the Deister/Gemini table top, then pour/apply the Truck bed liner/coating on the surface let it dry/settle , then remove the underside plywood and use the new formed Truck bed-liner/coating as the table deck NOT the plywood thing. Now you have a light weight,sturdy table deck surface that will withstand (I hope) the vigorous and tough usage as a shaker table deck surface. Just a concept, for further investigation.

  
baub
23:19:19 Sat
Feb 2 2013

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Re: Building a shaker table

I'm confused a bit. You have a great outer layer. Will you need an inner stiffener of some sort, or will the truck liner material be stiff enough?

b

  
Gani24
23:42:48 Sat
Feb 2 2013

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Re: Building a shaker table

Yeb, I guess you need some support under the molded surface but from what I 've seen the final product will be stiff by itself enough to be used separately , but this is all a theory I didn't built a table top deck in that way so I am not 100% sure, I need to build a prototype to prove that. Till then all I can say is keep your mind open for the possibilities out there

  

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