Need advice. I burned up two vibrators over the weekend... on my soil sifting table.

I built this vibrating sifting table for soil components:


Does a fairly good job.  Note the dust below:


The table is 6-feet by 2-feet and has removable screens.  The vibrating action is provided by an old bench grinder mounted at one end. I broke off a piece of one of the grinding discs to make it unbalanced and thus vibrate. The sad little thing died. It'll moan, and I got it spinning for a while, but I cannot get it going again.  I may take it apart this week to see if I can oil it somewhere.

I replaced it with another bench grinder I had in my workshop.  That guy lasted for about 90 minutes, then it died and blew a plume of smoke.  I have no hope for it.

Without spending $200 on a concrete table vibrator, does anyone have any suggestions on how I can provide a decent vibration to the table without shaking me down.*

Here's an action shot!


*I want to apologize for that pun, but I can't.

There is a very simple shaker we use down here that just - rocks - from side to side and sifts material.

Essentially, two boxes that fit into each other and a stand that holds the bottom box using a short pipe passing through the side.
If you are interested I can draw you a diagram.
It will handle two or three buckets of material at a go, and sift it clean in about 5 up and downs.
No need for electrics, just simple hand power.
Later.
Khaimraj

Interesting. Had to think about this for a while. The problem with unbalanced high speed motors as you've found out is they self destruct. Personally I would look at redesigning the whole thing, to have a mesh screen free to move on the base and something like a car windscreen wiper motor & linkage (which should be available cheaply from a junkyard) to attach to the screen as the power source. So the screen would move back & forth which should achieve the same result.


Dave

Ahhh mechanization.  If I had a setup -- or NEEDED a setup - with that large a screen, I think I'd mount it on legs, dump on however much unsifted soil it would hold, then give it a few swipes back and forth with a long handled push broom.  When all had been sifted that would sift, I'd lift one end and let it slide into the tub.  I think manpower will last a lot longer than cobbled together power.

How much soil do you make all at once, anyway?  I try to keep a bucketful handy, and when I need more I sit on my deck with my nested round sifters and make another bucket full -- or I used to.  These days I have to have someone else sift for me.  That's maybe twice a growing year.  Does fine for my 50-60 trees, not all of which need repotting every year.

This thread reminds me of Theopolis Thistle, the thrifty thistle sifter, who sifted sixteen thistles through the thick of his thumb (spoken quickly a few times, of course).

bill - best post title... EVER !      

Khaimraj Seepersad wrote:
If you are interested I can draw you a diagram. Khaimraj

khai - believe i can picture what you mean, but i would be interested in seeing a drawing
(i am contemplating building something along those lines but small scale)

pardon my crude drawing, but something like this:



i have a rolling cart that is only the frame from the bottom up, which is about a little over a meter or yard tall, to which i was planning on adding a top for a working surface (as i prefer to stand)... but i got to thinking that i could make the top removable and convertible to a sifting mechanism...

what i believe your idea is would be perfect... just a simple box with screen bottom, 2 holes though opposite sides and a pipe running through the holes... then just rest the pipe on the cart frame, fill up the box and rock it up and down a few times... with the material going onto a simple chute over a bucket...

when not in use, i store the screen(s) and bucket, etc on the bottom part of the cart...

i could even go one step further and make 3 box screens that nest together and connect with a simple hook and latch...
so then i could sift multiple sizes at once !!!

stoked !
gonna build it !!!

beer city snake wrote:bill - best post title... EVER !      

Quite. I wonder if it doesn't have the same meaning across the pond. I'm still sniggering though.

fiona wrote:

beer city snake wrote:bill - best post title... EVER !      

  Quite.  I wonder if it doesn't have the same meaning across the pond.  I'm still sniggering though.

Oh but it does.

before reading the text of the post, i was wondering how the title was even possible,
or what the hell they were even doing on a sifting table in the first place...

btw bill - i do know that the spin cycle of a washing machine has a... um... er... certain "attraction" when the load is unbalanced...
perhaps you could harness that power... ?
(and if you do... PATENT IT !!! )

JimLewis wrote:How much soil do you make all at once, anyway?

See that bag containing one cubic yard of haydite in the background?  About that much.  It's a bit more than 200 gallons unsifted.  My supplier is an industrial manufacturer and the cleanliness of the haydite varies.  This load is one of the best, but at the worst, I lost 60% of the load to being sandy dust.

I sell the soil to fellow enthusiasts.  I'm more than half-way through the bag, but I now have to sift pine-bark mulch.  I wanted to have about 20 5-gallon bags of soil (various percentage mixes) for a meet-up in Baton Rouge on the 17th.  

The table is very aggressive when it comes to sifting.  The unsifted material gets very fluid and runs off rather quickly.  I've had motor issues before (the electronics in the base shake themselves silly) and tried hand-shaking the stand.  There really is no comparison between the methods.  

Maybe my next motor will use a smaller wheel with a smaller offset weight.  The first motor was a 6-inch grinder, the second was an 8-inch grinder.  My method of measuring the weight was to use a hammer and just hit the wheel to break off a chunk.  I don't think I need to be so aggressive in unbalancing the weight.  The 8-inch grinder applied a great deal of torque in its self-immolation.  

I've also looked at doing this with a piston action. The benefit is that I'd get greater weight displacement (shake) with fewer revolutions. I currently use a router-control rheostat to control the motor. The problem is that I'd be increasing the size of the vibrating mechanism.

Bruce Winter wrote:

fiona wrote:

beer city snake wrote:bill - best post title... EVER !      

  Quite.  I wonder if it doesn't have the same meaning across the pond.  I'm still sniggering though.

Oh but it does.

I've been quite lucky with Google today.  I've been searching for "Vibrating table", "Vibrating table motor", "Vibrating motor animation", and such with no porn!  Well, "Safe Search" is currently set to "On", but still, you'd expect SOMETHING to slip through.

Here you are Kevin,

made from plywood and scrap lumber. One box fits into the other about 1.5 inches in [ 4 cm ] and the mesh is at the base of each box, held in place by wood strips.

All you have to do is load and rock.

You may wish to strengthen the base of the stand, I left out 2 more wood strips at the base of the stand for visual clarity.
The pipe is just galvanised piping.
Questions?
Later.
Khai......

Hook it all up to an exercise bike,keep yourself fit

BillsBayou wrote: does anyone have any suggestions on how I can provide a decent vibration to the table

Do you have a reciprocating saw? If so, maybe try strapping that to the table (without a blade) rather than a bench grinder, and see if that works. Mine at least vibrates a lot in use.

A jigsaw - again no blade - might work well too, and potentially be easier to fix to the table.

Have the motor spin a second shaft that holds the unbalanced weights. This will partially isolate the bearings in the motor from the vibration and increase the motor life. If you use a small pulley on the motor and a larger one one the second shaft you will reduce the vibration frequency as well.

I built a sieve composed of 4 concentric screens of different sizes so I can sieve into 4 size ranges + dust in one pass. It is driven by a low speed gear motor at about 6 - 8 rpm.


Marty

can't you use the motor to activate an imbalanced turning object instead of imbalancing the motor it self?
----I see i posted to slow....---

I'd say Kingfisher has the best answer.

Dirk Hoorelbeke wrote:can't you use the motor to activate an imbalanced turning object instead of imbalancing the motor it self?
----I see i posted to slow....---

Yes, with a cam lobe. Will describe later.

Google "build a dirt shaker table" lots of great ideas. What you are looking for is similar to archeology/forensics sifters, sifters that prospectors use amongst other endeavors. And I am with Jim, sit in a comfortable chair with my little sifters doing just a pail or so at a time.

And I am with Jim, sit in a comfortable chair with my little sifters doing just a pail or so at a time.

Don't forget the good, dark beer!

JimLewis wrote:

And I am with Jim, sit in a comfortable chair with my little sifters doing just a pail or so at a time.

Don't forget the good, dark beer!

glad to hear that your new meds aint preventing the enjoyment of some of the better things in life !!!